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In This Report

•	Highlights
•	Introduction
•	Dietary Changes
•	Lifestyle Changes
•	Resources
•	References

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Heart-Healthy Diet

Highlights

Soy

A rigorous review found that soy protein and isoflavone supplements do not help lower cholesterol or heart disease risk. However, soy foods are healthy choices, and the American Heart Association still recommends including them as part of a heart healthy diet. Skip the supplement pills.

Fish Oil Supplements

• Combining daily supplements of eicosapentaneoic acid (EPA), a type of fish oil, with statin medication may help prevent heart attack, angina, and coronary artery disease.
• Patients with implanted heart defibrillators should not take fish oil supplements because they could make heart rhythm problems worse.

Vitamin E

• The long-term Women’s Health Study reported that vitamin E supplements do not prevent heart attack or stroke.
• Vitamin E pills may increase the risk for heart failure, especially for patients with diabetes or vascular diseases.

Low-Carbohydrate Diets

Low-carb diets may help keep weight off for up to a year, but they appear to have mixed effects on cholesterol and lipid levels. On the positive side, they lower triglycerides and raise HDL (“good”) cholesterol. On the negative side, they raise overall and LDL (“bad”) cholesterol. Experts do not currently recommend low-carb diets for heart disease prevention.

Low-Fat Diets

Low-fat diets do not help prevent heart disease or stroke according to an important Women’s Health Initiative study. But some experts note that the study did not distinguish between good and bad types of fat.

Dietary Approaches to Stop Hypertension (DASH) Diet

The DASH diet is excellent for reducing blood pressure and has other heart healthy benefits. New research suggests that replacing some of the carbohydrates in the diet with protein or monounsaturated fat may help even more.

Calorie Restriction

Eating a low-calorie, but nutritionally balanced diet can help prevent age-associated heart disease. Patients in this study ate 1,400 – 2,000 calories a day.

Introduction

Heart-Healthy Goals. The goals of a heart-healthy diet are to eat foods that help obtain or maintain healthy levels of cholesterol and fatty molecules called lipids. You can achieve this by:

• 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

The U.S. Department of Agriculture discarded its nearly 15-year-old food pyramid in early 2005, opting for a new symbol that places more emphasis on portion control, healthy food choices, and regular exercise. The new model, called MyPyramid, is based on revised dietary guidelines which encourage people to eat more fruit, vegetables, whole grains, and fat-free or low-fat dairy products, and to reduce their intake of bad fats, cholesterol, salt, and added sugars.

Although there are many major dietary approaches for protecting health, experts generally agree on the following heart-smart recommendations:

• 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, legumes, poultry, and fish over meat. Fat-free and low-fat dairy products (skimmed milk, yogurt) are also healthy choices.
• Controlling weight, quitting smoking, and exercising are essential companions of any diet program.

After starting any heart healthy diet, it generally takes an average of 3 to 6 months before any noticeable reduction in cholesterol occurs, although some people have reported better levels in as few as 4 weeks. An intensive program may be necessary to achieve significant improvements in cholesterol levels and to reduce other heart risk factors.

Children

Atherosclerosis, the build-up of plaque in the arteries, begins in childhood. Experts stress the importance of heart healthy dietary guidelines for children and adolescents to help prevent the development of heart disease later in life. Children should eat foods that are low in saturated fat, trans fat, and cholesterol. These foods include:

• Fruits and vegetables
• Whole grains
• Low-fat and nonfat dairy products
• Beans, fish, and lean meats

Cholesterol is a soft, waxy substance that is present in parts of the body including the nervous system, skin, muscle, liver, intestines, and heart. It is made by the body and obtained from animal products in the diet. Cholesterol is manufactured in the liver and is needed for normal body functions, including the production of hormones, bile acid, and vitamin D. Excessive cholesterol in the blood contributes to atherosclerosis and subsequent heart disease. The risk of developing heart disease or atherosclerosis increases as the level of blood cholesterol increases.

[For more information on heart problems, see In-Depth Report #23: Cholesterol, Other Lipids, and Lipoproteins; Report #3: Coronary Artery Disease and Angina; Report #14: High Blood Pressure; Report #53: Weight Control and Diet.]

Fats and Oils

Some fat is essential for normal body function. Fats can have good or bad effects on health, depending on their chemistry. New research suggests that the type of fat is more important than the total amount of fat when it comes to reducing heart disease.

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 5 grams of fat. All fats, no matter what the source, add the same calories. The American Heart Association recommends that fats and oils have less than 2 grams of saturated fat per tablespoon.

Try to replace saturated fats and trans fatty acids with unsaturated fats from plant and fish oils. Omega-3 fatty acids, which are found in fish and plant sources, are a good source of unsaturated fats. Generally, two servings of fish per week provide a healthful amount of omega-3 fatty acids.

The Chemistry of Fats and Cholesterol.

• 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. Trans fatty acids are manufactured by adding hydrogen atoms to polyunsaturated fatty acids (a process called hydrogenation). This help keep foods fresh, or may be performed to produce a solid fat product, such as margarine.

Harmful Fats. Reducing consumption of saturated fats and trans fatty acids is the first essential step in managing cholesterol levels through diet. Experts say the combined amount of trans fat and saturated fat in the diet should not exceed 10 percent of the total calories consumed each day.

• 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. 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. (Tropical oils such as palm, coconut, and cocoa butter are also high in saturated fats.)

Click the icon to see an image of saturated fats.

• 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 are particularly dangerous for the heart and may pose a risk for certain cancers. 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. 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 ordered that food labels list the amount of trans fatty acids in food products beginning in January 2006.

Click the icon to see an image of trans fatty acids.

Beneficial Fats and Oils. 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.) Studies report 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).

Click the icon to see an image of omega-3 fatty acids.

• 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, inflammation, blood clotting factors, blood pressure, and improving triglyceride and HDL levels. Results from a study presented at the 2005 meeting of the American Heart Association suggested that daily EPA supplements plus statin therapy can protect against heart attack, angina, and coronary artery disease. However, although fish and fish oil are good for the heart, patients who have an implantable defibrillator should not take fish oil supplements. A 2005 study suggested that these supplements may make heart rhythm problems worse in some patients.
• 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, however.

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 may be associated 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.

Click the icon to see an image of different types of weight gain.

Omega-9 monounsaturated fatty acids are contained in canola and olive oil, which help protect the heart.

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 suggest 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. 

• Plants substances known as sterols, and their derivatives called stanols, reduce cholesterol by blocking its absorption in the intestinal tract. Margarines containing sterols (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 block absorption of fat-soluble nutrients or vitamins, as olestra does. 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 (Nu-Trim) may reduce cholesterol and have additional health benefits.

A number of other fat-replacers are also available. Although studies to date have not shown any significant adverse health effects, their effect on weight control is uncertain, since many of the products containing them may be high in sugar. One study suggested 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.

Click the icon to see an image of foods that contain cholesterol.

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 - 60% of the daily caloric intake. Many studies report that people can protect their heart and circulation by eating plenty of fruits and vegetables.

Complex Carbohydrates. 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 complex carbohydrates are high in fiber, which is important for health. Whole grains specifically are extremely important for people with diabetes or at risk for it.

Click the icon to see an image of complex carbohydrates.

Simple Carbohydrates (Sugar).  Experts 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:

Click the icon to see an image of simple carbohydrates.

• 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 different effects in the body than sucrose, most of the fruits and vegetables that contain it are vital for good health.

High levels of sugar consumption -- whether fructose or sucrose -- have been associated with higher triglycerides and lower levels of HDL cholesterol, the so-called good cholesterol. The high consumption of sugar is most likely one of the factors in the current obesity epidemic. Soda, other sweetened beverages, and fruit juice are major contributors to childhood obesity.

Possible harm from sugar comes from 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.

Click the icon to see an image of soluble and insoluble fiber.

Protein

In general, experts recommend that proteins should provide 12 - 20% of daily 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. Restrict intake of 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.

Click the icon to see an image of 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.

Some studies have 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 some extent, in tuna, trout, pike, tilapia, 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 guidelines recommend evidence eating fish two or three times a week.

Soy. Soy is an excellent food. It is rich in both soluble and insoluble fiber, omega-3 fatty acids, and provides all essential proteins. Soy proteins have more vitamins and minerals than meat or dairy proteins. They also contain polyunsaturated fats, which are better than the saturated fat found in meat. The best sources of soy protein are soy products (tofu, soy milk, soybeans). Soy sauce is not a good source. It contains only a trace amount of soy and is very high in sodium.

For many years, soy was promoted as a food that could help lower cholesterol and improve heart disease risk factors. But an important 2006 American Heart Association (AHA) review of studies found that soy protein and isoflavone supplement pills do not really have any effects on cholesterol or heart disease prevention. The AHA still encourages patients to include soy foods as part of an overall heart healthy diet, but does not recommend using isoflavone supplements.

Meat and Poultry. For heart protection, choose lean meat. 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 as well as their effect on LDL and HDL levels. However, even chicken and lean meat do not improve cholesterol levels and, in terms of heart 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. 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. The best dairy choices are low fat or fat free products.

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 initially observed favorable effects from vitamin E in preventing blood clots and preventing build-up of plaque on blood vessel walls, most studies found no heart protection from either vitamin E or C supplements. A 2005 Journal of the American Medical Association study found that vitamin E supplements can actually increase the risk of heart failure, especially for patients with diabetes or vascular diseases. Results from the long-term Women’s Health Study, also released in 2005, showed that vitamin E supplements do not protect women from attacks or stroke.

Click the icon to see an image of the benefits of vitamin C.

Click the icon to see an image of a cataract.

Click the icon to see an image of coronary artery disease.

Click the icon to see an image of phytochemicals.

B Vitamins (Folic Acid). Deficiencies in the B vitamins folate (known also as folic acid), B6, and B12 have been associated with a higher risk for heart disease in some studies. Such deficiencies produce higher blood levels of homocysteine, an amino acid that has been associated with a higher risk for heart disease, stroke, and heart failure. Researchers have been studying whether vitamin B supplements can reduce homocysteine levels and, consequently, heart disease risks.

Several major 2006 studies indicated that while B vitamin supplements help lower homocysteine levels, they have no effect on heart disease outcomes. The studies, published in the New England Journal of Medicine, examined patients who had either recently had a heart attack or who suffered from diabetes or heart disease. Results showed a similar number of heart attacks and strokes among patients who took folic acid and B6 and B12 vitamins and those who received placebo. And, the vitamins seemed to increase risks for patients who had undergone stenting. Some experts think that homocysteine may be a marker for heart disease rather than a cause of it.

Click the icon to see an image of sources of folate..

Click the icon to see an image of sources of B12.

Minerals

Potassium, Magnesium, and Calcium. Some experts believe that sufficient intake of minerals, particularly potassium, magnesium, and calcium, may be even more beneficial than salt restriction for reducing blood pressure.

• Potassium. Evidence 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 - 40%. Expert guidelines now support the use of potassium supplements or enough dietary potassium to achieve 3,500 mg per day for people who have no risk factors for excess potassium levels. (People who take potassium-sparing diuretics should not take potassium supplements.) This goal is particularly important for people who have a high sodium intake. The best source of potassium is from the fruits and vegetables that contain them. Potassium-rich foods include bananas, oranges, pears, prunes, cantaloupes, tomatoes, dried peas and beans, nuts, potatoes, and avocados.
• Magnesium. Some studies report that magnesium supplements may cause small but significant reductions in blood pressure. The recommended daily allowance is 320 mg. People who live in soft water areas, who use diuretics, or who have other risk factors for magnesium loss may require more dietary magnesium than others. No major studies have been done on long-term benefits or risks of magnesium supplements.
• Calcium. Calcium regulates the tone of the smooth muscles lining blood vessels. Studies have found that people who consume enough dietary calcium on a daily basis have lower blood pressure than those who do not. Hypertension increases calcium loss from the body. The effects of extra calcium on blood pressure, however, are mixed, with some showing higher pressure.

Click the icon to see an image of sources of calcium.

Salt Restriction

In the past, everyone was advised to consume less than 2,400 mg (about one teaspoon) of sodium (salt) each day. However, in February 2004, a long-awaited report by the Institute of Medicine (IOM) recommended that individuals slash their salt intake in half. The IOM report stressed that no one should consume more than 1,500 mg/day. Because blood pressure tends to rise with age, the Institute also suggested that people over 50 reduce their sodium intake to less than 1,300 mg daily; those over 70 should not eat more than 1,200 mg a day. Reducing sodium may also help protect against heart failure. Unfortunately many people find it very difficult to achieve these goals. Experts disagree on the overall benefits of salt restriction for everyone. Still, the following people 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 as 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. One 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. 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 increased with dehydration. In one 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.

Alcohol. A number of studies have found heart protection from moderate alcohol intake (one or two glasses a day). The benefits reported include 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. Alcohol may raise a man’s risk for atrial fibrillation according to a study in the Archives of Internal Medicine. 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 may offer protection against damaging forms of LDL.
• Coffee. Coffee, like red wine, contains phenol, which helps prevent oxidation of LDL cholesterol. However, 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.

Dietary Changes

Low Carbohydrate Diets

The Atkins diet restricts healthful complex carbohydrates in vegetables and particularly in fruits that are known to protect against heart disease. The Atkins diet also causes excessive calcium excretion in urine, which increases the risk for kidney stones and osteoporosis, and the release of ketones. An overload of ketones leads to ketosis, which can cause nausea, lightheadedness, and bad breath. A 2002 study suggested that such diets during pregnancy may increase the baby's risk for high blood pressure.

Low-carb diets such as South Beach, The Zone, and Sugar Busters rely on a concept called the "glycemic index," or GI, which ranks foods by how fast and how high they cause blood sugar levels to rise. Foods on the lowest end of the index take longer to digest. Slow digestion wards off hunger pains. It also helps stabilize insulin levels. But some doctors are having a tough time buying into this idea, which suggests that fruit or fruit products like orange juice and bananas, both high on the glycemic index, are bad for you.

A 2006 review of low-carbohydrate diets found that they did help weight loss in the short term. However, while these diets appeared to lower triglyceride and raise HDL (“good”) cholesterol levels, they also raised overall and LDL (“bad”) cholesterol levels. There is not yet enough evidence to indicate whether the good heart effects of these diets outweigh the bad effects. At this time, experts do not recommend low-carbohydrate diets for heart disease prevention.

Mediterranean Diet

The Mediterranean diet is rich in heart-healthy fiber and nutrients, including omega-3 fatty acids and antioxidants. The diet consists of fruits, vegetables, and unsaturated “good” fats, particularly olive oil. Olive oil has been associated with lower blood pressure, a lower risk for heart disease, and possible benefits for people with type 2 diabetes.

There are several variations to the Mediterranean diet but general recommendations include:

• Limit red meats.
• Drink one or two glasses of wine each day if alcohol is enjoyable and there are no reasons to restrict its use.
• Limit dairy products.
• Eat moderate amounts of fish and poultry. Fish is the diet’s main protein source. One study suggests that fish is the primary heart-protective ingredient in this diet.
• Eat plenty of fresh fruits and vegetables, nuts, legumes, beans, and whole grains.
• Season foods with garlic, onions, and herbs.

Positive Arguments. Even though fats make up about 40% of the calories found in the traditional Mediterranean diet, they are largely unsaturated. Growing evidence continues to support the heart-protective properties of the Mediterranean diet. Research has shown that such a diet reduces the risk for a second heart attack and helps cholesterol-lowering statin drugs work better.

Seniors who combine a Mediterranean diet with healthy lifestyle habits live longer lives, according to a 2004 study in The Journal of the American Medical Association. Researchers observed the effect of a Mediterranean diet on more than 2,000 elderly people for a period of 10 years, and measured the diet's effects on death rates alone and in combination with three risk factors: smoking, physical activity, and alcohol use. Overall, seniors who followed the Mediterranean diet decreased their risk of death from all causes by 23%. The elimination of each additional risk factor boosted their life expectancy rate even more. For example, non-smoking seniors on the diet who exercised regularly and drank only a moderate amount of alcohol reduced their death rates by 65%.

Negative Arguments. Weight gain due to a 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 a reduced consumption of dairy products. People on the diet should eat foods rich in iron or vitamin C, which aids in iron absorption. They should also ask their doctor if a calcium supplement may be needed because of a 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. 

DASH Diet

The DASH diet (Dietary Approaches to Stop Hypertension) is proven to help lower blood pressure. Results are sometimes seen within a few weeks. Restricting sodium improves results. The diet appears to have antioxidant effects and may help lower LDL cholesterol levels, although 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.

A diet that is effective in lowering blood pressure is called Dietary Approaches to Stop Hypertension (DASH).

The dietary recommendations are as follows:

• Reduce saturated fat (although include calcium-rich dairy products that are non- or low-fat.)
• When choosing fats, select monounsaturated oils, such as olive or canola oils.
• Choose whole grains over white flour or pasta products.
• Choose fresh fruits and vegetables every day. In one study people who increased their intake of fruits and vegetables experienced a drop in blood pressure after 6 months. Many of these foods are rich in potassium, fiber, or both which may help lower blood pressure.
• Include nuts, seeds, or legumes (dried beans or peas) daily.
• Choose modest amounts of protein (preferably fish, poultry, or soy products.)

Slight changes to the DASH diet might help lower blood pressure even more, as well as improve cholesterol and lipid levels. Researchers reporting in the Journal of the American Medical Association and at the 2005 American Heart Association meeting said that replacing some carbohydrates in the DASH diet with protein-rich foods from plant sources (nuts, seeds, soy) or monounsaturated fats (canola or olive oil) may help reduce heart disease risk factors.

Low-Fat Diets

Dietary guidelines recommend keeping total fat intake to 20 - 30% of total daily calories, with saturated fat less than 10% of calories. Low-fat diets generally restrict fat intake to 20% or less of total daily calories. The Ornish program, which is recommended for some heart disease patients, limits fats even more drastically. It aims at reducing saturated fats as much as possible, restricting total fat to 10%, and increasing carbohydrates to 75% of calories.

The Ornish program is a very 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 used.
• People do not smoke or drink more than two ounces of alcohol per day.

Positive Arguments.

• Low-fat programs may help keep weight off.
• 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 1 year and a 72% reduction after 4 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.

Negative Arguments.

• In 2006, the largest study-to-date on low-fat diets found that they did not help prevent heart disease or cancer. Women in the study reduced their fat consumption to 24 – 29% of total daily calories. Some critics say that the study did not do enough to distinguish between good types of fats (monounsaturated omega-3 polyunsaturated) and bad fats (saturated and trans fats).
• The American Heart Association notes that the Ornish program is so difficult to maintain that it will not benefit many people.
• Very low-fat diets may reduce calcium absorption, which may be particularly harmful for 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.

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. At this point, reducing calories and increasing exercise is still the best method for maintaining weight loss and preventing serious conditions, notably diabetes. A 2006 study reported that a low-calorie, but nutritionally balanced, diet can help prevent an aging-associated change in heart function. Patients in the small study took in 1,400 - 2,000 calories a day for an average of 6 years.

The standard dietary recommendations for losing weight are:

• 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). Saturated fats (found in animal products) should be avoided.

Lifestyle Changes

Inactivity is a major risk factor 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 lower their risk for heart disease only when they also follow a regular aerobic exercise program.

Research strongly supports the benefits 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 a significantly better chance of maintaining 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 be very important for patients with angina.

[For more information, see In-Depth 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 In-Depth Report #31: Stress.]

Resources

• www.nhlbi.nih.gov -- National Heart, Lung, and Blood Institute
• www.eatright.org -- American Dietetic Association
• www.americanheart.org -- American Heart Association
• www.acc.org -- American College of Cardiology
• www.nal.usda.gov/fnic -- Food and Nutrition Information Center

References

Appel LJ, Sacks FM, Carey VJ, Obarzanek E, Swain JF, Miller ER 3rd, et al. Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial. JAMA. 2005;294(19):2455-2464.

Bonaa KH, Njolstad I, Ueland PM, Schirmer H, Tverdal A, Steigen T, et al. Homocysteine lowering and cardiovascular events after acute myocardial infarction. N Engl J Med. 2006 Mar 12; [Epub ahead of print]

Gidding SS, Dennison BA, Birch LL, Daniels SR, Gilman MW, Lichtenstein AH, et al. Dietary recommendations for children and adolescents: a guide for practitioners. Pediatrics. 2006;117(2):544-559.

Howard BV, Van Horn L, Hsia J, Manson JE, Stefanick ML, Wassertheil-Smoller S, et al. Low-fat dietary pattern and risk of cardiovascular disease: the Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 2006;295(6):655-666.

Lee IM, Cook NR, Gaziano JM, Gordon D, Ridker PM, Manson JE, et al. Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women's Health Study: a randomized controlled trial. JAMA. 2005;294(1):56-65.

Lonn E, Bosch J, Yusuf S, Sheridan P, Pogue J, Arnold JM, et al. Effects of long-term vitamin E supplementation on cardiovascular events and cancer: a randomized controlled trial. JAMA. 2005;293(11):1338-1347.

Meyer TE, Kovacs SJ, Ehsani AA, Klein S, Holloszy JO, Fontana L. Long-term caloric restriction ameliorates the decline in diastolic function in humans. J Am Coll Cardiol. 2006;47(2):398-402.

Nordmann AJ, Nordmann A, Briel M, Keller U, Yancy WS Jr, Brehm BJ, et al. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006;166(3):285-293.

Raitt MH, Connor WE, Morris C, Kron J, Halperin B, Chugh SS, et al. Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial. JAMA. 2005;293(23):2884-2891.

Sacks FM, Lichtenstein A, Van Horn L, Harris W, Kris-Etherton P, Winston M; et al. Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee. Circulation. 2006;113(7):1034-1044.

The Heart Outcomes Prevention Evaluation (HOPE) 2 Investigators. Homocysteine lowering with folic acid and B vitamins in vascular disease. N Engl J Med. 2006 Mar 12; [Epub ahead of print]

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