DSI Newsletter: Heart-Healthy Diet

DSI Newsletters, Issue 58:
Heart-Healthy Diet

WHAT ARE THE IMPORTANT COMPONENTS OF A HEART-HEALTHY DIET?
Heart-Healthy Goals. The goals of a heart-healthy diet are to eat foods that help obtain or maintain healthy levels of cholesterol and other lipids (fatty molecules) by achieving the following:

Reducing overall cholesterol levels and low-density lipoproteins (LDL), which are harmful to the heart.
Increasing high-density lipoproteins (HDL), which are beneficial for the heart.
Reducing other harmful lipids (fatty molecules), such as triglycerides and lipoprotein(a).

Any diet should also help keep blood pressure and weight under control.
General Recommendations. Although there are many major dietary approaches for protecting health, experts generally agree on the following recommendations for heart protection:

Choose fiber-rich food (whole grains, legumes, nuts) as the main source of carbohydrates, along with a high intake of fresh fruits and vegetables.
Avoid saturated fats (found mostly in animal products) and trans fatty acids (found in hydrogenated fats and many commercial products and fast foods). Choose unsaturated fats, particularly omega-3 fatty acids (found in vegetable and fish oils).
In selecting proteins, choose soy protein, poultry, and fish over meat.
Weight control, quitting smoking, and exercise are essential companions of any diet program.

After embarking on any heart healthy diet, it generally takes an average of three to six months before any noticeable reduction in cholesterol occurs, although some people have reported better levels in as few as four weeks. An intensive program may be necessary to achieve significant improvements in cholesterol levels and to reduce other heart risk factors. [For more information on heart problems see Well-Connected Report #23 Cholesterol, Other Lipids, and Lipoproteins, Report #3 Coronary Artery Disease and Angina, Report #14 High Blood Pressure, and Report #53 Weight Control and Diet.]
Fats and Oils
Some fat is critical in everyone's diet, but certain fats have good or harmful effects on health, depending on their chemistry. All fats, good or bad, are high in calories compared to proteins and carbohydrates. In order to calculate daily fat intake, multiply the number of fat grams eaten by nine (one fat gram is equal to 9 calories, whether it's oil or fat) and divide by the number of total daily calories desired. One teaspoon of oil, butter, or other fats equals about five grams of fat. All fats, no matter what the source, add the same calories.
People should strive to replace saturated (animal fats) and trans fatty acids (commercial fats) with unsaturated fats from plant and fish oils. The American Heart Association and other experts now recommend that the source of most of these unsaturated fats should come from omega-3 fatty acids, which are found in fish and plant sources.
The Chemistry of Fats and Cholesterol. Most of the cholesterol in the body does not come from food but is produced by the liver -- stimulated by saturated fats. The dietary key to managing cholesterol, then, lies in understanding some of the major compounds in fats and oils that are becoming important in health:

Fatty Acids. All fats and oils found in foods are made up of chains of molecules called fatty acids. There are three major chains: saturated fatty acid (found mostly in animal products) and two unsaturated fatty acids — monounsaturated and polyunsaturated fatty acids (found in plant products). The oils and fats that people and animals eat are nearly always mixtures of these three chains, but one type of fatty acid usually predominates in specific oils or fats.
Essential Fatty Acids. In addition, there are three chemical subgroups of polyunsaturated fatty acids called essential fatty acids: omega-3 and omega-6 polyunsaturated fatty acids, and omega-9 monounsaturated fatty acids.
Trans Fatty Acids. To complicate matters, there are also trans fatty acids, which are not natural but are manufactured by adding hydrogen atoms to polyunsaturated fatty acids (called hydrogenation).

Harmful Fats. Reducing consumption of saturated fats and trans fatty acids is the first essential step in managing cholesterol levels through diet.

Saturated Fats. Saturated fats are found predominantly in animal products, including meat and dairy products. They are strongly associated with higher cholesterol levels, and they may be even more dangerous in women than in men. Avoiding fats during the evening meal may be especially helpful. High-fat meals are associated with sudden surges in triglyceride levels and other lipids along with impaired blood flow in the arteries to the heart. (The so-called tropical oils, palm, coconut, and cocoa butter, are also high in saturated fats. Evidence is lacking, however, about their effects on the heart. The countries with the highest palm-oil intake, Costa Rica and Malaysia, also have much lower heart disease rates and cholesterol levels than Western nations.)
Trans Fatty Acids. Trans fatty acids are manufactured fats created during a process called hydrogenation, which is aimed at stabilizing polyunsaturated oils to prevent them from becoming rancid and to keep them solid at room temperature. They may be particularly dangerous for the heart and may pose a risk for certain cancers. Some experts believe that these partially hydrogenated fats are even worse than saturated fats. Studies report that high consumption of these fats reduces HDL cholesterol levels, has harmful effects on the linings of the arteries, and may increase the risk for type 2 diabetes. Women whose diets were high in trans fatty acids, however, had a 53% increased risk for heart attack compared to those who consumed the least of those fats. Hydrogenated fats are used in stick margarine and in many fast foods and baked goods, including most commercially produced white breads. (Liquid margarine is not hydrogenated and is recommended.) The FDA has now required that food labels include information on trans fatty acids.

Beneficial Fats and Oils. It should be noted that some fat is essential for health, and fat is essential for healthy development in children. Public attention has mainly focused on the possible benefits or hazards of monounsaturated (MUFA) and polyunsaturated (PUFA) fats.

Polyunsaturated fats are found in safflower, sunflower, corn, and cottonseed oils and fish.
Monounsaturated fats are mostly present in olive, canola, and peanut oils and in most nuts. (Canola is the least saturated of all the fats.) Some studies have reported that replacing carbohydrates with monounsaturated fats improves glucose control after meals and reduces triglycerides in people with type 2 diabetes. Oils are more calorie-dense, however, and such patients should be wary of weight gain.

Researchers are most interested in the smaller fatty-acid building blocks contained in both oils, which may have more specific effects on lipids. Three important fatty acids are the essential fatty acids omega-3, omega-6, and omega-9. Omega-3 fatty acids are found in fish oil (docosahexaenoic and eicosapentaneoic acids) and plants ( alpha-linolenic acid).

Docosahexaenoic (DHA) and Eicosapentaneoic (EPA) Acids. DHA and EPA are found in fish oils, and evidence suggests that they have significant benefits for the heart, including reducing sudden death from heart disease, dangerous heart rhythms, inflammation, blood clotting factors, blood pressure, and improving triglyceride and HDL levels. These fatty acids may also reduce risks for other disorders, including stroke, rheumatoid arthritis, asthma, ulcerative colitis, some cancers, and mental decline. Fish oil supplements may increase LDL levels in certain people and impair short term control of blood sugar in people with type 2 diabetes. The significance of these findings is not yet known. [For more information, see Fish under Protein, below.]

Alpha-linolenic Acid. Alpha-linolenic acid is a plant precursor of DHA, which means the body can convert it to DHA. Sources include canola oil, soybeans, flaxseed, and certain nuts and seeds (walnut, flax, chia and sometimes pumpkin seed). Some, but not all, studies suggest that oils or foods containing these oils may also be heart-protective. Supplements or foods containing this oils may also protest the heart. For example studies have reported heart protection from flaxseed supplements and also from nuts, such as almonds, macadamia, and walnuts. Nuts are high in calories, although studies in 2002 reported that replacing usual snacks with almonds did not affect the daily diet and significantly reduced cholesterol and other heart disease risk factors. Still, people must be aware of that nuts are not low-calorie snacks. Omega-6 polyunsaturated fatty acids are found in corn, safflower, soybean, and sunflower oil. PUFA oils containing omega-6 fatty acids constitute most of the oils consumed in the US. Some omega-6 fatty acids are important for health. However, high intake of these fats was associated in one study with weight gain in the abdomen (the so-called apple shape), a risk factor for heart disease. High consumption is also associated with a higher risk for certain cancer and some chronic diseases.

Omega-9 monounsaturated fatty acids are contained in canola and olive oil, which have bother been associated with health protection.
Research suggests that a healthy balance of all these fats may be important and that our current Western diet contains an unhealthy ratio of omega-6 to omega-3 fatty acids (10 to 1). Omega-9 fatty acids may also contain chemicals that block harmful factors found in omega-6 fatty acids. Researchers are finding then that the most benefits may be found in mixture of all three fatty acids found in both poly- and monounsaturated oils, but in modest amounts that do not add too many calories.
Fat Substitutes. Fat substitutes added to commercial foods or used in baking, deliver some of the desirable qualities of fat, but do not add as many calories. Some include the following:

Plants substances known as sterols and their derivatives called stanols reduce cholesterol by impairing its absorption in the intestinal tract. Margarines containing them (Benecol, Take Control) are available. Benecol is derived from pine bark and Take Control from soybeans. Two servings a day of either brand as part of a low-fat diet can lower LDL and total cholesterol. In one study, consuming a sterol-based margarine doubled the LDL-lowering effects of a statin (a common cholesterol-lowering drug) compared to a standard margarine. These products do not appear to have block absorption of fat-soluble nutrients or vitamins, as olestra does [see below]. They may be hydrogenated and include some trans fatty acids, however.
Olestra (Olean) passes through the body without leaving behind any calories from fat. Studies suggest that it helps improve cholesterol levels and may help overweight people lose weight. Early reports of cramps and diarrhea after eating food containing olestra have not proven to be significant. Of greater concern is the fact that even small amounts of olestra deplete the body of certain vitamins and nutrients that may help protect against serious diseases, including cancer. The FDA requires that the missing vitamins be added back to olestra products, but not other nutrients.
Beta-glucan is a soluble fiber found in oats and barley. Products using this substance (e.g., Nu-Trim) may reduce cholesterol and have additional health benefits.

A number of other fat-replacers are also available. Although studies to date are not showing any significant adverse health effects, their effect on weight control is uncertain, since many of the products containing them may be high in sugar. Of interest was one study suggesting that people who consume foods that contain fat substitutes do not learn to dislike fatty foods, while people who learn to cook using foods naturally lacking or low in fat eventually lose their taste for high fat diets. It should be stressed that eliminating all fats from ones diet can be harmful to general health.
Note on Dietary Cholesterol
The story on cholesterol found in the diet is not entirely straightforward. Cholesterol is found only in animal tissues, with high amounts occurring in meat, dairy products, egg yolks, and shellfish. The American Heart Association recommends no more than 200 mg of cholesterol per day. One study estimated, however, that reducing dietary cholesterol intake by 100 mg/day would only produce a 1% decrease in cholesterol levels. And eggs specifically have many nutrients. Most people, then, can eat eggs occasionally without concern.
Studies now suggest that dietary cholesterol itself may not pose any significant risk for heart disease in most individuals. Exceptions may be people with diabetes, who should still avoid eating eggs or other high-cholesterol foods (such as shrimp) more often than once a week.
Carbohydrates
Carbohydrates are either complex (as in starches) or simple (as in fruits and sugars). One gram of carbohydrates equals four calories. The current general recommendation is that carbohydrates should provide between 50% and 60% of the daily caloric intake. Important studies are reporting that individuals can protect their heart and circulation and even extend their lives just by eating plenty of fruits and vegetables.
Complex Carbohydrates. In all cases, complex carbohydrates found in whole grains and vegetables are preferred over those found in starch-heavy foods, such as pastas, white-flour products, and potatoes. Most of these are high in fiber, which is important for health. Whole-grains specifically are extremely important for people with diabetes or at risk for it. [See Box Fiber-Rich Foods and Table Some Examples of Healthy Foods.]
Simple Carbohydrates (Sugar). The World Health Organization and the Food and Agriculture Organization now recommend that no more than 10% of daily calories should come from sugar. (Currently, Americans eat nearly half a pound of sugar a day on average, and sugar intake constitutes 25% of a day's calories.) Sugars are usually one of two types:

Sucrose. Source of most dietary sugar, found in sugar cane, honey, and corn syrup.
Fructose. Found in fruits and vegetables. Although fructose does not appear to be have any difference effects in the body than sucrose, most of the fruits and vegetables that contain it are vital for good health.

High level of sugar consumption — whether fructose or sucrose — has been associated with higher triglycerides and lower levels of HDL cholesterol, the so-called good cholesterol. And the high consumption of sugar is most likely one of the factor in the current obesity epidemic. Soda, other sweetened beverages, and fruit juice in fact may be singled out as major contributors to childhood obesity.
Of increasing interest to researchers in the study of possible harm from sugar are advanced glycation end-products (called AGEs), which are end-products of the chemical reaction between sugar and protein. This reaction occurs most intensively when cooking at high temperatures — particularly animal fats. (Steaming or cooking food in water does not produce these chemicals. Low, slow cooking also produces fewer AGEs.) AGEs can also be formed by chemical reactions in the body itself. They are now believed to promote factors in the inflammatory response that cause a number of diseases or their complications, including Alzheimer's disease, diabetes, atherosclerosis, cataracts, and osteoporosis.
Fiber-Rich Foods
Fiber is an important component of many complex carbohydrates. It is almost always found only in plants. (One exception is chitosan, a dietary fiber made from shellfish skeletons.) Fiber cannot be digested but passes through the intestines, drawing water with it and is eliminated as part of feces content. High-fiber diets (up to 55 grams a day) can be very helpful. Different fiber types may have specific benefits:

Insoluble fiber (found in wheat bran, whole grains, seeds, nuts, legumes, and fruit and vegetable peels) may help achieve weight loss. Consuming whole grains on a regular basis may lower the risk for heart disease, improve factors involved with diabetes, and may even lower the risk for type 2 diabetes in the first place.(Wheat bran taken as supplements has not been associated with any benefits. The whole grain may be needed for good health.) Of further note, high consumption of nuts, such as almonds, macadamia, and walnuts) may be highly heart protective, independent of their fiber content.
Soluble fiber (found in dried beans, oat bran, barley, apples, citrus fruits, and potatoes) may help achieve healthy cholesterol levels and possibly reduce blood pressure as well. For example, a 2001 study indicated that eating beans four or more times a week reduced the risk for heart disease by 22%. Oat bran has also been highly studied for its benefits on the heart.
Soluble fiber supplements, such as those that contain psyllium or glucomannan, may be beneficial. Psyllium is taken from the husk of a seed grown in India and is a very effective agent for lowering total and LDL cholesterol. It is found in laxatives (e.g., Metamucil), breakfast cereals (Bran Buds, Plantaben), and other products. Of note, some studies suggest that psyllium increases triglyceride levels in postmenopausal women. Sodium levels may also rise. People who increase intake of soluble fiber should also drink more water.

Protein
In general, experts recommend that proteins should provide 12% to 20% of calories. One gram of protein contains four calories. Protein is important for strong muscles and bones and may have specific benefits on blood pressure. The best sources of protein are fish, poultry, and soy. At this time, it is wise to restrict red meat or any meat that is not lean. Fish. Fish is probably the best source of protein. Evidence suggests that eating moderate amounts of fish (twice a week) may improve triglyceride and HDL levels and help lower the risks for death from heart disease, dangerous heart rhythms, blood pressure, a tendency for blood clots, and the risk for stroke. The most healthy fish are oily fish, such as salmon, mackerel, or sardines, which are high in omega-3 fatty acids. Three capsules of fish oil (preferably as supplements of DHA-EPA) is about equivalent to eating one serving of fish.
It should be noted that a French study reported a higher incidence of heart attack in men who ate fish daily. Such findings may be due to mercury toxicity, which has harmful effects on the heart. High mercury content has been observed in swordfish and shark and, to a medium extent, in tuna, trout, pike, tilapia (tile fish) and bass.Fish oil supplements also may have some adverse effects on LDL levels in certain people and glucose control in people with type 2 diabetes. More research is needed to further define the risks and benefits of fish, but at this time most evidence for eating fish two or three times a week is highly positive for most people. [See Beneficial Fats and Oils under Fats and Oils, below.]
Soy. Soy is an excellent food. It is rich in both soluble and insoluble fiber, omega-3 fatty acids, and provides all essential proteins. Not all studies are consistent, but the majority has shown an improvement in at least one of the cholesterol components in people who consumed at least 25 grams of soy protein. Soy may also reduce other heart risk factors, at least in certain populations.For example, in one 2002 study, soy was beneficial for controlling blood sugar and lowering LDL in postmenopausal women with type 2 diabetes. In another study, soy protein was associated with lower systolic blood pressure in men. The best sources are soy products (tofu, soy milk) or whole soy protein. Adding soy to lean ground beef may still provide heart benefits and be more acceptable for people who object to soy's taste or its "veggie" image. (Note: Tablets of individual isoflavones -- chemicals, such as genistein or daidzein, found in soy — do not appear to offer any advantages. Soy sauce is also not a good source. It contains only a trace amount of soy and is very high in sodium.) More research is important to determine if soy has long-term complications. Of possible concern, a high intake of soy during pregnancy may have some adverse effect on the fetus, although only animal studies have suggested this.
Meat and Poultry. For heart protection, one 1999 study suggested that it didn't matter if you chose fish, poultry, beef, or pork as long as the meat was lean. (Saturated fat in meat is the primary danger to the heart.) The fat content of meat varies depending on the type and cut. It is best to eat skinless chicken or turkey. However, the leanest cuts of pork (loin and tenderloin), veal, and beef are nearly comparable to chicken in calories and fat and their effect on LDL and HDL levels. It should be noted, however, that even chicken and lean meat do not improve cholesterol levels, and, in terms of cardiac health, fish is a more desirable choice.
Dairy Products. A 2002 study reported a lower incidence of factors related to type 2 diabetes and heart disease (insulin resistance, high blood pressure, obesity, and unhealthy cholesterol) with a high intake of dairy products, including those with a high-fat content. Some researchers suggest the calcium in dairy products may be partially responsible for these benefits. The effects of extra calcium on blood pressure, however, are mixed with some even showing higher pressure. Because many dairy products are high in saturated fats, which are related to heart disease, this study requires confirmatory evidence.

May have activity against certain cancers (lung), heart disease, asthma, and type 2 diabetes.

**Some Examples of Healthy Foods**
Foods	Important Phytochemicals (Plant chemicals) Contained in the Foods	Vitamins and other valuable food components	Possible Benefits
Apples	Flavonoids	Fiber
Avocados		Vitamin E, vitamin B6, folate	May be heart protective
Beans	Flavonoids	Folate, iron, potassium and zinc, fiber	Some experts believe beans are the perfect food.
Berries, All kinds of dark colored	Ellegic Acid	Vitamin C, minerals	May protect the aging brain. (In one study blueberries were most effective.)
Broccoli (also kale, Brussels sprouts, cauliflower)	Flavonoids, Isothiocyanates	Vitamin C, folate, fiber, and selenium	Anticancer properties. Protective against heart disease and stroke.
Carrots and other bright yellow vegetables	Lutein, Beta carotene	Vitamin A (converted from carotenoids), Vitamin C, fiber	Protects heart, eyes, lungs. (Cooking carrots may increase their benefits.)
Fish (particularly oily fish, such as mackerel, salmon, sardines)		Vitamin B3 and B12, Essential fatty acids, selenium	Heart and brain protective.
Garlic	Allium (organosulfurs)		May be slightly protective against heart disease. Possible infection fighter.
Ginger	Zingiberaceae		Cancer fighting properties.
Grains (whole)	Lignans (phytoestrogens)	Vitamin B, Selenium (important antioxidant mineral), fiber, folate	May help reduce the ability of cancer cells to invade health tissue.
Grapes and Red wine	Flavonoids, resveratrol		Fights heart disease and cancer. May have activity against asthma, and type 2 diabetes.
Nuts (such as almonds, macadamia, and walnuts)		Vitamin E, Vitamin B1, Essential fatty acids, folate, fiber	May lower cholesterol levels, reduce sudden death rates from heart disease, and help prevent stroke and type 2 diabetes.
Onions	Flavonoids, allium (organosulfurs)		May have activity against certain cancers (lung), heart disease, asthma, and type 2 diabetes.
Oranges and orange juice	Monoterpenes	Vitamin C, folate, potassium, fiber	Many health benefits. Increases HDL levels and helps maintain normal blood pressure.
Potatoes (Sweet)		Vitamins A, C, and E	Many health benefits.
Soy: Four ounces of tofu equals about eight to 13 grams of soy. A soy burger contains about 18 grams of soy.	Isoflavones (phytoestrogens), flavonoids, phytosterol, phytate, saponins		May have effects similar to estrogen, including maintaining bone and benefiting the heart. May also be protective against prostate cancer and possibly other cancers. Possible protection against mental decline. More studies are needed.
Spinach and other dark green leafy vegetables	Zeaxantin, Beta carotene	Vitamin C, folate, Vitamin A (converted from carotenoids)	Protects heart, lungs and brain.
Tea (Green tea has reported best benefits.)	Flavonoids		Both black and green tea are heart protective and may protect against stroke. Cancer-fighting properties, particularly in green tea (probably not black tea).
Tomatoes	Lycopene, Flavonoids	Vitamin C, biotin, minerals	Protects heart. Studies suggest reductions in prostate and other cancers. Infection fighters.

Vitamins
Antioxidant Vitamins E, C, and A. Vitamins E, C, and A are most studied for their health effects because they serve as antioxidants. Antioxidants are chemicals that act as scavengers of particles known as oxygen-free radicals (also sometimes called oxidants). High intake of foods rich in these vitamins (as well as other food chemicals) have been associated with many health benefits, including prevention of heart problems. Research on the effects of vitamin supplements on heart disease and diabetes, however, has been mixed. Although some research has observed favorable effects from vitamin E in preventing blood clots and preventing build-up of plaque on blood vessel walls, most studies have found no heart protection from either vitamin E or C supplements. In fact, there is some evidence that high doses of antioxidant vitamin can be harmful. [See Box Oxygen-Free Radical and Antioxidants.]
Vitamin E, however, is still of interest to researchers for possible benefits for people with diabetes. Nevertheless, the recent negative findings on antioxidant supplements and the lack of clear evidence on benefits should caution against supplements unless people have diets or conditions that cause deficiencies in these vitamins.
Oxygen-Free Radicals and Antioxidants
Antioxidants are chemicals that act as scavengers of particles known as oxygen-free radicals (also sometimes called oxidants). These chemically active particles are by-products of many of the body's normal chemical processes. Their numbers are increased by environmental assaults, such as smoking, chemicals, toxins, and stress. In higher levels, oxidants can be very harmful:

Oxygen-free radicals can damage cell membranes and interact with genetic material, possibly contributing to the development of a number of disorders including diabetes, cancer, heart disease, cataracts, and even the aging process itself.
They can also enhance the dangerous properties of low-density lipoprotein (LDL) cholesterol, a major player in the development of coronary artery disease.

Antioxidant vitamins (A, C, and E), beta carotene, and many phytochemicals can neutralize free radicals and have been studies for possible benefits. It is clear that such vitamins are required to prevent deficiency diseases. In addition, foods rich in antioxidants are important disease fighters. To date, however, there is no strong evidence that antioxidant supplements offer any real protection.
Special Warning on High-Dose Antioxidant Supplements. Some studies are now suggesting that excessive use of antioxidant supplements may interfere with other nutrients or convert into pro-oxidants and become harmful. Some of the findings are as follows:

One small study found that high doses of antioxidants, including vitamins C and E, interfered with cholesterol-lowering drugs and blunted their effect. This study also supports other evidence that high doses of vitamin C may speed up atherosclerosis. A 2002 randomized study of postmenopausal women, for example, found a higher risk for heart disease in those who took vitamin E and C supplements.
Of particular concern are studies that have found an increase in lung cancer and overall mortality rate among smokers who took beta carotene supplements. A 2000 study further reported a higher risk for cancer in male smokers who took multivitamins plus A, C, or E. In determining reasons for this disturbing effect, one animal study suggested that beta carotene increased enzymes in the lungs that actually promote cancerous changes. Even more worrisome, in people with existing cancer, high doses of antioxidant vitamins, such as vitamin C or beta carotene, may actually protect cancer cells (just as they do healthy cells).

B Vitamins. Deficiencies in the B vitamins folate and B12 have been associated with a higher risk for heart disease in some (but not all) studies. Such deficiencies produce elevated blood levels of homocysteine, an amino acid that has been associated with a higher risk for heart disease. Some experts believe, however, that high levels of homocysteine are only indicators, not causes, of heart problems. Folate improves blood flow through the arteries, which may be as important for the heart as its effect on homocysteine.
Minerals
Potassium, Magnesium, and Calcium. Some experts believe that sufficient intake of minerals, particularly potassium, magnesium, and calcium, may be more beneficial than salt restriction for reducing blood pressure.

Potassium. Evidence now strongly indicates that a potassium-rich diet can help achieve healthy blood pressure levels, and that potassium supplements can lower systolic blood pressure by 1.8 m Hg and diastolic blood pressure by 1 mm Hg. In fact, there is some evidence that a potassium-rich diet can reduce the risk of stroke by 22% to 40%. Current expert guidelines now support the use of potassium supplements or enough dietary potassium to achieve 3,500 mg per day for people with normal or high blood pressure (who have no risk factors for excess potassium levels). This goal is particularly important in people who have high sodium intake. The best source of potassium is from the fruits and vegetables that contain them. Some potassium-rich foods include bananas, oranges, pears, prunes, cantaloupes, tomatoes, dried peas and beans, nuts, potatoes, and avocados. Some patients, such as those taking certain diuretics that do not spare potassium, may require supplements. It should be noted, that excess potassium can cause abdominal distress, muscle weakness, and, in rare cases, dangerous heart events. Some people should be particularly cautious about excess potassium, including those with conditions, such as diabetes or kidney disease, that increase potassium levels or people who are taking medications, such as ACE inhibitors or potassium-sparing diuretics, that limit the kidney's ability to excrete potassium.
Magnesium. Some studies reported that magnesium supplements may induce small but significant reductions in blood pressure. The recommended daily allowance is 320 mg. Persons who live in soft water areas, who use diuretics, or who have other risk factors for magnesium loss or ectopic beats may require more dietary magnesium than would others. No major studies, however, have been done on long-term benefits or risks of magnesium supplements. A major 2001 study on diet found no effect on blood pressure from magnesium intake from foods.
Calcium. Calcium regulates the tone of the smooth muscles lining blood vessels, and population studies have found that people who have sufficient dietary calcium have lower blood pressure than those who do not. Hypertension itself increases calcium loss from the body. The effects of extra calcium on blood pressure, however, are mixed with some even showing higher pressure.

Salt Restriction
Everyone should consume less than 2,400 milligrams (about one teaspoon) of sodium each day. People with hypertension should strive for even lower intake. Reducing sodium may also help protect against heart failure. It should be noted, however, that experts disagree on the overall benefits of salt restriction for everyone. Still, the following specific groups should take particular measures to restrict salt:

People at Risk for Salt-Sensitivity. About half of people with hypertension have blood pressure that reacts significantly to salt. Such people are known to be salt-sensitive. Among those at highest risk for salt sensitivity are African Americans, people with diabetes, and elderly people.
Overweight People. Overweight individuals may absorb and retain sodium differently from people with normal weights. In fact, one 1999 study reported that high sodium intake was associated with an increased risk of heart disease and all-cause mortality in overweight, but not in normal weight, people. Reducing sodium can also help reduce the risk of stroke in people who are overweight.

Simply eliminating table and cooking salt can be beneficial. Salt substitutes, such as Cardia, containing mixtures of potassium, sodium, and magnesium are available, but they are expensive. It should be noted, however, that about 75% of the salt in the typical American diet comes from processed or commercial foods, not from food cooked at home, so the benefits of table-salt substitutes are likely to be very modest. Some sodium is essential to protect the heart, but most experts agree that the amount is significantly less than that found in the average American diet. If people cannot significantly reduce the amount of salt in their diets, adding potassium-rich foods might help to restore a healthy balance.
Water and Other Fluids
Water. Many heart risk factors, especially those associated with blood clotting, are elevated with dehydration. In an interesting 2002 study, drinking five or more glasses of water a day was significantly associated with a lower risk for fatal heart events than drinking two or fewer glasses a day. More research is warranted on this simple way of protecting health. (Other fluids, including caffeinated and sugared drinks, were not protective.)
Alcohol. A number of studies have found heart protection from moderate intake alcohol (defined as one or two glasses a day). The benefits reported have been higher HDL levels, blood clot prevention, and anti-inflammatory properties. Although red wine is most often cited for healthful properties, any type of alcoholic beverage appears to have similar benefit. On the negative side, an estimated 10% of hypertension cases are caused by alcohol abuse. Men with hypertension should limit their intake to an average of no more than one or two drinks a day, and women (especially those at risk for breast cancer) and lighter people should also drink less. Pregnant women, people who can't drink moderately, and people with liver disease should not drink at all.
Caffeinated Beverages.

Tea. Although it contains caffeine, tea, both black and green, is often cited for its health benefits. Green tea especially is rich in chemicals that offer protection against damaging forms of LDL. In one study, for example, higher intake, particularly by women, was associated with a lower risk for severe coronary artery disease.
Coffee. Coffee, like red wine, contains phenol, which helps prevent oxidation of LDL cholesterol. Studies are finding no association between coffee consumption and fatal or nonfatal heart disease even after 10 years. In fact, in one study the highest rates of fatal heart disease were in non-coffee drinkers, and women who increased their coffee intake reduced their mortality rates. On the downside, unfiltered coffee (Turkish coffee, Scandinavian boiled or French pressed coffee, and espresso) contains an alcohol called cafestol, which may raise cholesterol and triglyceride levels. Filtered coffee does not contain this residue. Coffee drinking is associated with small increases in blood pressure, but the risk it poses is very small in people with normal blood pressure. People with existing hypertension should avoid caffeine altogether.

WHAT ARE SOME SPECIFIC DIETARY APPROACHES FOR ACHIEVING A HEALTHY HEART?
Currently, there is much controversy over the best balance of carbohydrates, fats, and protein. A number of dietary approaches for improving the heart are available:

Therapeutic Lifestyle Changes (TLC) from the National Cholesterol Education Program.
The Mediterranean Diet.
Very low-fat diets, particularly the Ornish Program.
The Dietary Approaches to Stop Hypertension (DASH) diet. This diet has been designed specifically to help people reduce blood pressure.
Restricted calorie diets.
High-protein diets (e.g., the Atkins diet).

Although all the major dietary approaches differ in important aspects, they have some recommendations in common:

Choose fiber-rich food (whole grains, legumes, nuts) and fresh fruits and vegetables.
Avoid saturated fats and trans fatty acids and choose unsaturated fats.
In selecting proteins, choose soy, poultry, and fish over meat.
Weight control and exercise are essential companions of any diet program.

Timing of Meals
Eating small frequent meals (six or more instead of two or three large ones) has been associated with being thinner and having a better cholesterol profile. Naturally, findings should not be taken as a license to snack on high-sugar or commercial packaged snacks, soda and sugar sweetened beverages (including too much juice), and fast foods in general. Snacking on such foods is a fast track to obesity.
Low-calorie snack packages (Lean on Me, Level Best) are being developed for people with type 2 diabetes that contain supplements (such as psyllium, barley, fructose, green-tea extract, chromium picolinate and 5-http) associated with claims for improving factors that affect the heart and diabetes. Although promising, these packages have not been clinically studied, and patients should be warned that their long-term risks and benefits are not known.
Therapeutic Lifestyle Changes (TLC) from the National Cholesterol Education Program Guidelines in 2001 from the National Cholesterol Education Program include the following for preventing and managing high cholesterol levels in adults:

Choose five or more servings of fresh fruits and vegetables and six or more servings of whole grains, legumes. Soluble fiber is preferred (from cereal grains, beans, peas, legumes, and many fruits and vegetables).
Fats can be up to 35% of daily calories, but no more than 7% should be from saturated fat. (People with high triglycerides or low HDL or both may need a higher fat intake.) Choose fats containing unsaturated fatty acids (from vegetables, fish, legumes, and nuts). Choose margarines containing sterols or stanols (e.g., Benecol, Take Control). Avoid trans fatty acids found in commercial products as much as possible.
Proteins choices should be limited in general to fat-free and low-fat milk products, fish, legumes, skinless poultry, and lean means.
Limit cholesterol intake to less than 200 mg per day.
Maintain healthy body weight and a healthy level of physical fitness.

Mediterranean Diet
The Mediterranean diet is rich in heart-healthy fiber and nutrients, including omega-3 fatty acids and antioxidants. The diet recommends the following:

A relatively high fat intake (about 35% to 45% of daily calories), but mostly from monounsaturated and polyunsaturated oils. The Mediterranean diet is known specifically for its use of olive oil. Extra virgin olive oil has been associated with lower blood pressure. Other studies have reported an association between olive oil and a lower risk for heart disease as well as possible benefits for people with type 2 diabetes.
Daily glass or two of wine.
Protein source is primarily fish. In fact, one 2001 study suggested that fish-consumption was the primary heart-protective ingredient in this diet.
Carbohydrate choices emphasize fresh fruits and vegetables, nuts, legumes, beans, and whole grains.
Foods seasoned with garlic, onions, and herbs.

Positive Arguments. Evidence is increasingly strong on the heart-protective properties of the Mediterranean diet. In a 2002 study, it not only enhanced the benefits of a cholesterol-lowering statin drug, it also maintained levels of antioxidant nutrients that are normally decreased with the statin. One study suggested that is significantly lowered the risk for a second heart attack after an average of four years compared to a conservative Western diet. Some studies have reported that it is more beneficial than the previous American Heart Association Step 1 and 2 diets, although there are no comparison studies yet with the more recent AHA approach.
Negative Arguments. Weight gain from the high intake of fats and risk for alcohol abuse can be problems with the Mediterranean diet. Other concerns include reduced iron levels and possible calcium loss resulting from consumption of fewer dairy products. People who use the diet should take the following precautions:

Cook in iron pans.
Eat foods that contain iron or are rich in vitamin C, which aids in iron absorption.
A calcium supplement may also be needed because of lack of dairy products.
People should avoid wine if they have risk factors for complications from alcohol. Such people include women who are pregnant or at risk for breast cancer and anyone prone to alcohol abuse.

The Ornish Program and Severely Fat-Restricted Diets
The Ornish program limits fats significantly. It aims at reducing saturated fats as much as possible, restricting total fat to 10%, and increasing carbohydrates to 75% of calories. It is a very effective but demanding regimen:

It excludes all oils and animal products except nonfat yogurt, nonfat milk, and egg whites.
Foods stressed are whole grains, legumes, and fresh fruits and vegetables.
People in the program exercise for 90 minutes at least three times a week.
Stress reduction techniques are employed.
People do not smoke or drink more than two ounces of alcohol per day.

People on low fat diets should consume a wide variety of foods and take a multivitamin if appropriate.
Positive Arguments. A 2001 systematic review of 27 studies reported that reducing dietary fat is associated with a 16% reduction in risk and a 9% decline in mortality rates. Low-fat diets that are high in fiber, whole grains, legumes, and fresh produce offer health advantages in addition to their effects on cholesterol.

The Ornish program directors have reported a 91% reduction in angina after one year and a 72% reduction after four years in spite of significant HDL cholesterol reduction. One study reported that the diet reduced LDL levels to recommended levels without the addition of a cholesterol-lowering drug.
A major analysis of low-fat diets reported a 9% reduction in mortality rates and 16% reduction in cardiovascular events (such as heart attack and stroke).
It is effective in keeping weight off.
It protects against high blood pressure.
It may possibly protect against certain cancers.

Negative Arguments. The American Heart Association argues that the Ornish program is so difficult to maintain that it will not benefit many people. The comparison study showing the advantage of the Ornish over the Step 2 diet, in fact, was very small because few participants could sustain the efforts needed to fulfill the requirements of the Ornish program for five years.
Some experts argue that it is not clear whether fat-restriction or the other elements in the program, exercise and stress reduction, are mainly responsible for its benefits.

High-carbohydrate and low-fat diets can reduce HDL levels and increase blood sugar and triglyceride levels. (In such cases, however, people may have chosen their carbohydrates primarily as simple sugars, not the complex carbohydrates found in whole grains and fresh fruits and vegetables.)
Very low-fat diets may also increase the risk for stroke from hemorrhage in the brain.
Very low fat diets may reduce calcium absorption, which may be particularly harmful in women at risk for osteoporosis.
Many people who reduce their fat intake do not consume enough of the basic nutrients, including vitamins A and E, folic acid, calcium, iron, and zinc. People on low fat diets should consume a wide variety of foods and take a multivitamin if appropriate.

The DASH Diet and Other Dietary Considerations for Reducing High Blood Pressure
The DASH diet (Dietary Approaches to Stop Hypertension) is proving to help lower blood pressure after eight weeks. Restricting sodium improves results. The diet appears to have antioxidant effects and may even prove to be a good diet for lowering LDL cholesterol levels — although the beneficial HDL levels also decline.
This diet is not only rich in important nutrients and fiber but also includes foods that contain far more electrolytes, potassium, calcium, and magnesium, than are found in the average American diet. The dietary recommendations are as follows:

Avoid saturated fat (although include calcium-rich dairy products that are no- or low-fat).
When choosing fats, select monounsaturated oils, such as olive or canola oils. (One study reported a reduced need for anti-hypertension medication in people with a high intake of virgin olive oil, but not sunflower oil, a polyunsaturated fat.)
Choose whole grains over white flour or pasta products.
Choose fresh fruits and vegetables every day. In one 2002 study people who increased their intake of fruits and vegetables experienced a drop in blood pressure after six months. Many of these foods are rich in potassium, fiber, or both which may help lower blood pressure. [For a list of foods containing potassium, see Potassium, below.]
Include nuts, seeds, or legumes (dried beans or peas) daily.
Choose modest amounts of protein (preferably fish, poultry, or soy products). Soy in combination with fiber-rich foods or supplements may have specific benefits. Oily fish may also be particularly beneficial. They contain omega-3 fatty acids, which have been associated with heart and nerve protection. [For more information see Well-Connected Report #14 High Blood Pressure.]

Calorie Restriction
Calorie restriction has been the cornerstone of weight-loss programs. Restricting calories in such cases also appears to have beneficial effects on cholesterol levels, including reducing LDL and triglycerides and increasing HDL levels. In fact, in a study of an African community, inhabitants had very-low calorie diets and favorable cholesterol levels in spite of a relatively high intake of saturated fats. [Also see Box Guidelines for Weight Loss.]
The standard dietary recommendations for losing weight are the following:

As a rough rule of thumb, one pound of fat equals about 3,500 calories, so one could lose a pound a week by reducing daily caloric intake by about 500 calories a day. Naturally, the more severe the daily calorie restriction, the faster the weight loss.
To determine the daily calories requirements for specific individuals, multiply the number of pounds of ideal weight by 12 to 15 calories. The number of calories per pound depends on gender, age, and activity levels. For instance a 50-year old woman who wants to maintain a weight of 135 pounds and is mildly active might require only 12 calories per pound (1,620 calories a day). A 25-year-old female athlete who wants to maintain the same weight might require 25 calories per pound 2,025 (calories a day).
Fat intake should be no more than 30% of total calories. Most fats should be in the form of monounsaturated fats (such as olive oil) and saturated fats (found in animal products) should be avoided.

Guidelines for Weight Loss
Life-long changes in eating habits, physical activity, and attitudes about food and weight are essential to weight management. Unfortunately, although many people can lose weight initially, it is very difficult to maintain weight loss. People with type 2 diabetes may have a particularly difficult time. The following offer some general suggestions that may be helpful:

Start with realistic goals. It is important to realize that when overweight people achieve even modest weight loss they reduce risk factors in the heart. Ideally, however, overweight patients should strive for 15% weight loss or better, particularly people with type 2 diabetes.
A regular exercise program is essential for maintaining weight loss. If there are no health prohibitions, choose one that is enjoyable. Check with a physician about any health consideration. [For more information, see Well-Connected Report #29 Exercise.]
Hunger pangs should not be taken as cues to eat. A stomach that has been stretched by large meals will continue to signal hunger for large amounts of food until its size reduces over time with smaller meals.
Be honest about how much you eat, and track calories carefully. Studies on weight control that depend on self-reporting of food intake frequently reveal that subjects badly misjudge how much they eat (typically underestimating high-calories foods and over-estimating low-calorie foods). In one study, even dietitians underreported their calorie intake by 10%! People who do not carefully note everything they eat tend to take in excessive calories when they believe they are dieting.
For patients who cannot lose weight with diet along, effect weight-loss medications are now available, which include sibutramine (Meridia) and orlistat (Xenical). Orlistat may have particularly benefits for patients with type 2 diabetes. This drug may delay or even prevent the onset or progression of diabetes. It may also improve cholesterol levels, regardless of weight loss. Sibutramine is also helpful in weight loss but should not be used by patients with high blood pressure or kidney or liver problems.
Once a person has lost weight, maintenance is required. To maintain a healthy weight in our culture, everyone must make daily, even hourly, decisions about what is consumed and what is expended through activity. Such thinking, in many cases, can become automatic and not painful.
Procedures known as bariatric surgeries have been very helpful in producing rapid weight loss and even improving insulin and glucose levels in people with diabetes.

Even repeated weight loss failure is no reason to give up. Most studies indicate that yo-yo dieting or weight cycling has no adverse psychological or physical effects. (Of some concern was a 2000 study reporting lower HDL levels, the so-called good cholesterol, in women whose weight cycled from frequent dieting. No other heart risks were evident, however.) Repeated dieting also does not impair the body's ability to burn calories efficiently. or symptoms and by the adoption of healthy lifestyle habits, not by just the number of pounds lost. [For more detailed information, see Well-Connected Report #53 Weight Control and Diet.]
High-Protein Diets
High-protein, low-carbohydrate diets have become popular again. They include the Zone, Dr. Atkins, Protein Power, Sugar Busters, and Dr. Stillman. As an example, the Atkins diet has a four-phase program:

For the first two weeks individuals consume no more than 20 grams of carbohydrates a day (no fruit, bread, grains, starchy vegetables, or dairy products other than cheese, cream or butter.) They eat pure protein and fats. (This phase is not suitable for children, pregnant women, or anyone with kidney disease.)
After the first phase, individuals continue to lose weight while they increase carbohydrate levels by five grams each week.
When individuals get close to their weight goal, they add another 10 grams of carbohydrates per week as long as they do not begin to gain weight. Weight loss is very slow at this time, but the individual is now getting used to maintenance.
Lifetime maintenance is usually between 40 and 100 grams of carbohydrates a week. Anyone who chooses this diet should prefer fish or soy products to meat as protein sources. Fish, in fact, may reduce leptin, a hormone associated with fat storage and heart diseases, and so be the best protein source. People on this diet should also select monounsaturated fats (as in olive oil) over other fat sources.) Patients often need supplements, at least a multivitamin and possibly calcium, chromium, omega-3 fatty acids (found in fish oil), and other supplements.

High-protein diets can be very effective in producing short-term weight loss, but their long-term effects on health or on weight maintenance are in question. Centers that promote this approach argue that heart problems from obesity are due to insulin disturbances from sugar imbalances.
In fact, a well publicized 2002 study reported that people on the Atkins experienced lower levels of triglycerides (unhealthy fat molecules) and higher HDL (so-called cholesterol), while those on the American Heart Association diet experienced the reverse effects — which are risk factors for heart disease. It should be noted that in the study, people on the Atkins diet — and not those on the AHA diet — were given supplements of omega-3 fatty acids, which are known to be heart-healthy. In assessing the study, some experts suggest that its major contribution to information on diet is the possible limitation of the AHA diet — not necessarily the healthy implications of the Atkins diet. Long term effects on health are still unknown.
For example, the Atkins diet restricts healthful complex carbohydrates in vegetables and particularly in fruits that are known to protect against serious diseases — not only heart problems but also cancer. The Atkins diet also causes excessive calcium excretion in urine, which increases the risk for kidney stones and osteoporosis. One byproduct of this diet is the release of substances called ketones, which can cause nausea, lightheadedness, and bad breath. A 2002 study suggested that such diets during pregnancy may increase the risk for high blood pressure in the offspring. At this point, restricting calories on a low-fat diet is still the best proven method for maintaining weight loss and preventing serious conditions — notably diabetes.
WHAT OTHER LIFESTYLE CHANGES SHOULD ACCOMPANY A HEART-HEALTHY DIET?
Exercise
Inactivity is one of the four major risk factors for coronary artery disease, on par with smoking, unhealthy cholesterol, and high blood pressure. In fact, studies suggest that people who change their diet in order to control cholesterol are successful in actually lowering their risk for heart disease only when they also follow a regular aerobic exercise program.
The following are some observations on the effects of exercise on coronary artery disease:

People who maintain an active lifestyle have a 45% lower risk of developing heart disease than do sedentary people. Even moderate exercise reduces the risk of heart attack.
People who lose weight and exercise regularly have significantly better chance of maintaining that weight loss compared to those who do not exercise.
Some studies suggest that for the greatest heart protection, it is not the duration of the exercise that counts but the total daily amount of energy expended. Therefore, the best way to exercise may be in multiple short bouts of intense exercise.
Burning at least 250 calories a day (the equivalent of about 45 minutes of brisk walking or 25 minutes of jogging) seems to confer the greatest protection against coronary artery disease, particularly by raising HDL (the so-called good cholesterol) levels. (It may take up to a year of sustained exercise for HDL levels to show significant improvement, but in terms of raising HDL levels, more is better.)
Aerobic exercise also appears to open up the blood vessels and, in combination with a healthy diet, may improve blood-clotting factors.
Resistance (weight) training offers a complementary benefit by reducing LDL (the so-called bad cholesterol) levels.
Exercises that train and strengthen the chest muscles may prove to be very important for patients with angina. [For complete information, see Well-Connected Report #29 Exercise.]

Stress Reduction
Stress is always highly associated with negative effects on the heart and other parts of the body. A number of techniques are available to help people relax and reduce tension. [See Well-Connected Report #31 Stress.]

**Key Components of a Lifestyle Change Program**
Lifestyle	Reduce rate of eating. Keep food records. Eliminate environmental triggers to eating. Identify high-risk situations for overeating. Uncouple eating from other activities.
Exercise	Confront psychological barriers to exercise. Understand mechanisms linking exercise to weight control. Establish reasonable exercise goals. Develop a plan for regular activity. Integrate increased activity into daily lifestyle.
Attitudes	Develop reasonable weight-loss goals. Avoid "all or none" thinking. Focus attention away from the scale and toward behavior. Uncouple weight from self-esteem. Recover from lapses with constructive action (relapse prevention)
Relationships	Understand the key role of social support to health. Identify supportive others. Match personal style to support-seeking activities. Be specific in making support requests. Be assertive but reinforcing in drawing help from others.
Nutrition	Resist the lure of popular fad diets. Develop pro-health rather than restriction mentality about eating. Eat with moderation in mind. Maximize fiber. Develop a tailored plan.
From Brownell KD. The LEARN Program for Weight Control. 7th ed. Dallas, Tex: American Health Publishing Company; 1998.

WHERE ELSE CAN INFORMATION ABOUT HEART-HEALTHY DIETS BE OBTAINED?
National Heart, Lung, and Blood Institute Call (301-251-1222). Provides excellent free information, including Step by Step, Eating to Lower Your High Blood Cholesterol.
American Dietetic Association Call (800-366-1655). This site offers good, recent information on nutrition and has an excellent searchable database for dietitians within a particular locality in a desired specialty, including eating disorders and weight control.
American Heart Association Call (800-242-8721). This is the primary source of information about heart problems. They will send free pamphlets and reading material, including useful diet information and locations of local representatives.
The Ornish Program
Iowa State University nutrition information
International Food Information Council
Nutrition Analysis Tool
Good list of fiber-rich foods
International Society for the Study of Fatty Acids and Lipids
For more information on soy, visit or call (1-800-TALKSOY).
DASH Diet
This site offers a useful heart risk evaluation test
This site provides a good list of fiber-rich foods
FIND A HEART SPECIALIST
FIND A DIETICIAN
FIND A DIET OR CHOLESTEROL DRUG STUDY

Review Date: 3/31/2003

Reviewed By: Harvey Simon, MD, Editor-in-Chief, Well-Connected reports; Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2003 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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