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Reducing Blood Cholesterol Without Drugs

From our January 2001 issue

The past decade has seen increased usage of a number of drugs aimed at reducing cholesterol levels and the risk for heart disease. In particular, a class of drugs called statins, which work by inhibiting the synthesis of cholesterol by the liver, have been highly successful and widely prescribed. Studies show that they reduce total cholesterol levels by between 19 and 26% and LDL-cholesterol is reduced by 25 to 36%. Recent data suggest that heart disease risk is about 30% lower in people on statins.1 In truth, drugs can be an important and very easy way to fight heart disease. They can be especially useful for people at very high risk of coronary heart disease and for those who are genetically predisposed to high blood cholesterol levels.

But drugs are not without their downside. They can be expensive, and many have side effects. Research also shows that many older people do not take their medications regularly and properly.

Perhaps even more importantly, drugs can promote a false sense of security about heart disease and overall health. While they may lower cholesterol, they don’t affect other areas of health or other risk factors for heart disease. In contrast, a diet that helps to fight heart disease may also have effects on risk for other chronic diseases, like cancer, diabetes, and rheumatoid arthritis.

But can diet be as strong a defense against heart disease as powerful medications? Evidence suggests that it can. Research on the effects of a comprehensive lifestyle program that included a mostly plant food diet produced reversals in heart disease once thought to be achievable only through drug therapy. More recently, the Nurses’ Health Study showed that just a few lifestyle factors–including exercise, avoiding smoking, decreasing intake of trans fatty acids, and getting enough folate–could reduce risk for heart disease by more than 80%. These studies and others show that a healthful lifestyle is every bit as good as drugs for reducing heart disease risk.

Dietary factors, especially those in plant foods, help to reduce heart disease risk in a number of ways. Although reducing levels of blood cholesterol isn’t the only way in which heart disease risk is reduced, it is certainly one of the most important. Studies indicate that for every 1% decrease in blood cholesterol levels, risk for heart disease drops as much as 3 to 4%. In this issue of VNHL, we look at some of the dietary factors that have been shown to lower blood cholesterol. In a future issue, we’ll look at some of the other ways that diet affects heart disease risk.



Reducing Saturated Fat and Cholesterol

The American Heart Association’s dietary prescription for reducing heart disease risk is the National Cholesterol Education Program (NCEP) diet. The first step is the NCEP-I diet, which reduces saturated fat intake to no more than 10% of calories and cholesterol intake to 300 milligrams. If this diet does not produce the desired drop in cholesterol, the NCEP-II diet, which is no more than 7% saturated fat and provides no more than 200 milligrams of cholesterol, is recommended. Both diets derive no more than 30% of total calories from fat. Despite a plethora of research on this subject, there is no universally accepted view on the extent to which the NCEP-II diet will lower cholesterol. Generally though, estimates are that the NCEP-I diet reduces cholesterol levels by approximately 5 to 10% compared to the standard American diet. Changing to a NCEP-II diet may lower levels by as much as much as 13%. However, some studies suggest that the NCEP-II diet also significantly lowers levels of the good HDL-cholesterol. To avoid this undesirable effect, some researchers recommend replacing some of the polyunsaturated fat in the NCEP diet with monounsaturated fat. However, it is not clear that HDL cholesterol would be affected by this, because it is not known if the effect of monounsaturated on cholesterol is different from that of polyunsaturated fat. And we don’t know for sure that polyunsaturated fat lowers HDL. Whether or not the NCEP dietary approach reduces actual heart disease risk has not been shown. Some critics of this approach say that the diet does not go far enough and that other approaches are likely to be more effective. For example, typical vegetarian diets are often lower in saturated fat and cholesterol compared to the NCEP diets.

Soluble Fiber

The Food and Drug Administration has authorized the inclusion of 14 official health claims on food packages. Two of these deal directly with the relationship of fiber to heart disease. One focuses on the fiber in oats and the other on psyllium fiber. Psyllium products are a combination of natural and concentrated fiber derived from the husks of psyllium seed. It’s been marketed as an over-the-counter laxative for more than 60 years in the United States. In a review of studies that examined the effect of a standard 10.2- gram dose of pysllium fiber, researchers from the University of Kentucky concluded that total cholesterol levels are lowered approximately 4%, but LDL-cholesterol, the more important factor, is lowered by about 7%. These decreases occurred in people who were already following a NCEP-I diet. However, despite the health claim, there have not been any studies to determine whether these supplements actually decrease heart disease risk (as opposed to just reducing cholesterol).

In a review of 67 controlled trials of dietary fiber and cholesterol, Brown and colleagues from Harvard University concluded that fiber only modestly decreases cholesterol, and there was little difference among the types of soluble fiber (psyllium, oat bran, pectin, and guar gum) on cholesterol levels. They found, for example, that 3 g of soluble fiber (from three 28-gram servings of oatmeal, or three apples) would lower cholesterol levels by only about 2%. Therefore, they concluded that the major benefit of eating fiber-rich foods may be a change in dietary pattern, resulting in a diet that is lower in saturated and trans fatty acids and cholesterol and higher in protective nutrients such as unsaturated fatty acids, minerals, folate, and antioxidant vitamins. This suggests that, while fiber from supplements would lower cholesterol as much as a similar amount of fiber from foods, it may not be as beneficial as eating more high-fiber foods.

Fiber seems to lower cholesterol by binding bile acids in the intestine, causing them to be excreted. This causes less cholesterol to be synthesized by the liver because compounds needed to synthesize cholesterol are diverted towards the manufacture of more bile acids.

Soy Protein

A third health claim approved by the FDA relates to soy protein and its effects on risk of heart disease. The health claim is for a specific amount of protein–25 grams per day. A food must contain at least 6.25 grams of soy protein to qualify, since the assumption is that people can consume four servings of these foods per day. However, including foods that are higher in soy protein may be necessary for most people to achieve an intake of 25 grams. Many beverages and energy bars formulated with soy protein isolate contain 10 to 20 grams of soy protein per serving. Also, many soy burgers have 10 to15 grams per patty, and soynuts provide about 17 grams per one-fourth cup. One-half cup of firm tofu provides 12 grams of protein. However, traditional soymilk contains only about 6 grams per cup.

Soy protein effectively lowers blood cholesterol, but only in people with elevated levels. In people with blood levels between 260 and 300, it is not uncommon to see decreases of 15 to 25%. Compared to other dietary approaches, this is very impressive. However, in people with blood levels of cholesterol between 220 and 240 mg/dl, the effect is rather modest, lowering levels on average by less than 5%. For people with cholesterol levels below 220, soy may not significantly impact serum cholesterol and the effect may differ among individuals.

However, because soyfoods often replace meat and full-fat dairy foods in the diet, both significant contributors of saturated fat and cholesterol, adding more of these soyfoods can be a good way to make your diet more heart healthy.

Nuts

In the past decade, 13 published studies have looked at the relationship between nut consumption and blood cholesterol levels. All have found that nuts have a favorable effect on cholesterol. In a recent study from Loma Linda University, a low-saturated-fat Mediterranean-style diet that included walnuts lowered cholesterol to a greater extent than a similar diet that didn’t include nuts. It’s not surprising that nuts lower cholesterol. Although they are a high-fat food, they are rich in monounsaturated and polyunsaturated fat and low in saturated fat. As we’ve seen above, replacing saturated fat with unsaturated fat reduces blood cholesterol. What is surprising is that nuts lower cholesterol to an even greater extent than we would predict from their fatty acid profile. This suggests that a number of factors in nuts affect blood cholesterol levels. For example, plant protein has a more favorable effect on blood cholesterol than animal protein. The protein in nuts has a similar amino acid profile to that in soy. Nuts are also a good source of soluble fiber.

Phytosterols

Both phytosterols and cholesterol are members of a family of compounds called sterols. They have almost identical chemical structures, but small differences in their shape and structure translate to big differences in how they affect health. Phytosterols, found naturally in high-fat plant foods, are converted to phytostanols through a commercial chemical process called hydrogenation. Although initial research suggested that these hydrogenated products are better at lowering cholesterol, more recent research shows this is not the case.

Plant sterols are very effective in lowering cholesterol over a wide range of levels. In response to about 2 g of phytosterols/phytostanols per day, one can expect to see a reduction of 10 to15% even in people with fairly normal cholesterol levels. The effects may be greater in older people than younger people. Furthermore, phytosterols work even in people who are already on low-fat diets. And although they have usually been consumed in three doses per day, recent research indicates that consuming phytosterols just once per day is as effective as long as the total intake of phytosterols is the same.

Phytosterols work by blocking the absorption of dietary cholesterol and also by blocking the re-absorption of cholesterol that circulates throughout the body. Most of this cholesterol comes from synthesis in the liver; thus phytosterols work even in people who are on low-cholesterol diets. However, they are most effective in people who absorb dietary cholesterol at higher-than-average rates.

The FDA has tentatively approved a health claim for the cholesterol-lowering effects of phytosterols. Fortified salad dressing and margarines are now on the market and new phytosterol-containing energy bars and cereals will soon be available. You can increase your intake of phytosterols by including small amounts of vegetable oils in your diet, although these amounts may have more modest affects on cholesterol levels than fortified products.

Garlic

Garlic has been big health news for many years. Several large analyses of its cholesterol-lowering properties suggested that garlic lowered cholesterol by 9 to 12%. However, the authors of one of these analyses suggested that the impressive results may be due to publication bias. This can occur because groups that fund studies can often decide whether or not to publish the results, and because journals prefer to publish studies with positive results. It appears likely that many studies finding that garlic had no effect went unpublished. Thus, there remains somewhat of a controversy about the effects of garlic. This is further complicated by the many types of garlic preparations on the market and the possibility that these preparations have different effects on cholesterol.

The most recent analysis of the garlic literature by researchers from the University of Exeter in the United Kingdom involved 13 different trials. Results indicated that garlic lowered cholesterol on average by about 16 mg compared to placebo; this was a decrease of about 6%. However, when considering only the six trials that met the criteria for good experimental design, the results were less impressive. Garlic lowered cholesterol by only about 4.3 mg, an effect that was not statistically significant. Thus, at the moment, it does not appear that garlic consumption represents an effective way to lower cholesterol.

Cholestin

Without question, the most effective "dietary agent" for lowering cholesterol is cholestin. Cholestin is produced by Phamanex of Simi Valley, Calif., and refers to red yeast rice, which is fermented rice on which red yeast has been grown. The use of red yeast rice in China was first documented more than 1,000 years ago. In a recent study that involved 83 men and women with high cholesterol, 2.4 g of cholestin per day decreased cholesterol from an average of 254 mg/dl to 208 mg/dl over an eight-week period. This result is generally only seen with drugs. In fact, cholestin is so potent because, in a sense, it is a drug. Cholestin contains statin compounds that lower cholesterol in the same way as the statin drugs, by inhibiting the synthesis of cholesterol. Thus, there is quite a controversy about whether the cholestin product is a dietary supplement or a drug. In July of this year, the 10th US Circuit Court of Appeals ruled that cholestin is subject to USFDA regulation as a drug product, so it is not clear what the final status of cholestin will be.



Fenugreek

The seeds of this herb are often used in Indian cookery as part of some curry recipes. It contains a type of fiber called mucilage. Fenugreek has demonstrated effectiveness in reducing blood cholesterol levels in humans. In a 1990 study in India, people with insulin-dependent diabetes were given 100 grams of defatted fenugreek powder. The powder was incorporated into meals. Both total and LDL cholesterol were reduced significantly compared to a control group. Importantly, the fenugreek didn’t lower the good HDL cholesterol. Blood glucose was also reduced, suggesting that fenugreek could be especially valuable for people with diabetes. In a 1997 study, also in India, feeding 5 grams of fenugreek daily didn’t affect blood cholesterol in healthy people, but it caused a decrease in those who had both diabetes and coronary heart disease. Again, HDL cholesterol wasn’t affected. Five grams of fenugreek is a little less than a quarter of an ounce, so these effects may be important in cultures where fenugreek is often included in the diet.

Conclusion

With the exception of the diet/drug cholestin, no single dietary agent or change will lower cholesterol to the extent that statins do. However, researcher David Jenkins at the University of Toronto contends that a combination of dietary changes can produce drug-like results. That is, a diet that contains sufficient amounts of soy protein, soluble fiber, plant sterols, and is low in saturated fat, in combination with weight loss (for overweight people) may lower cholesterol by 20 to 30%. This has not yet been demonstrated experimentally so it is not clear that all these effects are additive. Research does suggest that the effects of soy protein and soluble fiber are additive, however.

Undoubtedly though, the major advantage to lowering cholesterol through overall dietary change is that diet has multiple other effects on health. While cholesterol-lowering drugs may lower cholesterol, they may not affect other important risk factors for heart disease, such as reducing clot formation and reducing cholesterol oxidation. This same criticism can be applied to fiber supplements or phytosterol-containing margarines. Eating fiber-rich plant foods to increase fiber intake, and substituting soyfoods for animal products to increase soy protein intake and decrease saturated fat intake may do much more to lower heart disease risk than would be predicted by their effects on cholesterol levels.


Loma Linda University

dnyc99

Great find hun.

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