16 Foods Proven to Lower Cholesterol

There is enough evidence to assert that diets including nuts on a regular basis reduce the risk of coronary heart disease.

A number of epidemiologic studies have consistently reported an inverse relation between the incidence of cardiovascular disease and the frequent consumption of nuts, even after adjustment for confounding variables. Five large prospective cohort studies (the Adventist Health Study, the Iowa Women Health Study, the Nurses’ Health Study, the Physicians’ Health Study, and the CARE Study) have examined the relation between nut consumption and the risk of atherosclerotic heart disease, and all have found a strong inverse association. When 21,454 male participants enrolled in the U.S. physicians’ study were followed for an average of 17 years, researchers found a lower risk of sudden cardiac death and other coronary heart disease end points after controlling for known cardiac risk factors and other dietary habits. When compared with men who rarely or never consumed nuts, those who consumed nuts two or more times per week had reduced risks of sudden cardiac death by over 50 percent.

Series of well controlled dietary intervention studies have shown that the incorporation of nuts to any diet lowers total serum cholesterol and improves the lipoprotein profile. A review of 23 intervention trials using nuts demonstrated convincingly that eating nuts daily decreases total cholesterol and LDL cholesterol[34].

Many studies have shown that oats, when combined with other cholesterol-lowering foods, can have a big effect on cholesterol levels[41-42]. In a study[41] published in the American Journal of Clinical Nutrition in 2005, researchers tested cholesterol-lowering drugs against cholesterol-lowering foods in a group of thirty-four adults with high cholesterol. Oat products were among the chosen foods. The results were striking. The diet lowered cholesterol levels about as well as cholesterol drugs.

The mechanism by which soluble fiber reduces LDL cholesterol is similar to the action of bile acid-binding resins, which are a type of medications used to control cholesterol levels. The fiber binds to bile acids and inhibits the formation of micelles. Micelles are tiny chemical complexes needed for the absorption of cholesterol and other fats in the gut. If the micelles cannot form, your body cannot absorb cholesterol and fat when you eat it. Bile acids themselves are also prevented from being reabsorbed. This prevention of bile acid resorption disrupts the pool of bile acids that are available to the body. This triggers another mechanism in the liver which causes the conversion of cholesterol into new bile salt acids, thus lowering cholesterol in the blood.

Scientific evidence continues to demonstrate that the consumption of barley products is effective for lowering total and LDL cholesterol.

Most clinical studies evaluating the effects of soluble fibers have used oats or psyllium even though barley contains at least as much beta-glucan as they do.

A combination of factors and mechanisms appears to contribute to the cholesterol lowering action of barley. Soluble fiber is suggested to reduce cholesterol by increased excretion of bile acids or neutral sterols, increased catabolism of LDL cholesterol, and reduced absorption of fat. Soluble fibers were shown to be fermented in the colon and thus to give rise to short-chain fatty acids that can be absorbed and may inhibit hepatic cholesterol synthesis. In addition to the soluble fiber, barley contains a wide range of phytochemicals, some of which are being investigated for their effect on metabolism.

Barley's cholesterol-lowering power was seen in a small study of 25 people with mildly elevated cholesterol levels[55]. Beta-glucan, a soluble fiber found in many whole grains, came exclusively from barley and not supplements. The diet with the most beta-glucan used barley flakes, barley flour, and pearled barley instead of rice and wheat. The barley-based foods made a difference. When participants ate diets with low, medium, and high levels of the soluble fiber beta-glucan, their total cholesterol dropped by 4%, 9%, and 10%, respectively. The diets with low, medium, and high beta-glucan levels cut LDL cholesterol by 8%, 13.8%, and 17.4%, respectively.

Data from several human intervention trials indicate that consumption of canned and dry beans reduce serum cholesterol[28-31]. Only two studies[32-33] did not found favorable changes in serum lipoproteins when beans were consumed. Generally, in carefully controlled clinical studies where the macronutrient intake was matched and the fiber content in the bean fed group was at least twice that of the control diet, significant reductions in both total and LDL cholesterol occurred. Significant increases in HDL cholesterol or reductions in triglycerides were also seen in several but not all of the studies.

In one test, 1 cup of canned baked beans in tomato sauce decreased cholesterol by 10 percent in middle-aged men with high cholesterol who ate a typical high-fat diet[28].

Researchers found that daily pinto bean consumption of a half-cup resulted in an average drop of total cholesterol and LDL cholesterol of more than 8 percent[29]. In this study the black-eyed peas appeared to have little effect on blood cholesterol.

In another study 20 men with hypercholesterolemia were randomly allocated 100 g of oat bran or 115 g (4 oz) of pinto and navy beans per day[31]. After 21 days, an average reduction of 19 percent in total serum cholesterol levels occurred in both the oat bran and bean groups. LDL cholesterol levels for the oat bran and bean groups were reduced by 23 percent and 24 percent, respectively.

Soya controversy

In 1995, the New England Journal of Medicine published a report from the University of Kentucky entitled, "Meta-Analysis of the Effects of Soy Protein Intake on Serum Lipids." It was financed by the PTI division of DuPont, "The Solae Co." St. Louis, Missouri, a soy producer and marketer. This meta-analysis concluded that soy protein is correlated with significant decreases in serum cholesterol, LDL cholesterol and triglyceride concentrations. But, HDL cholesterol did not increase by a significant amount.

However, this earlier research indicating that soy protein has clinically important favorable effects on LDL cholesterol and other CVD risk factors has not been confirmed by many studies reported during the past 10 years. A very large amount of soy protein, more than half the daily protein intake, may lower LDL cholesterol by a few percentage points when it replaces dairy protein or a mixture of animal proteins.

The Nutrition Committee of the American Heart Association has assessed 22 randomized trials conducted since 1999 and found that isolated soy protein with isoflavones (ISF) slightly decreased LDL cholesterol but had no effect on HDL cholesterol, triglycerides, or blood pressure[59].

Regular red wine consumption reduces LDL cholesterol levels and increases HDL cholesterol. This is supported by considerable data from epidemiological studies (studies focused on disease within whole populations) and strong suggestions from experimental (interventional) research[15,20]. HDL cholesterol enhancing effects of red wine are attributed to both the alcohol component[17] and to antioxidant functions of its flavonoids[16,18].

High quality study[19] has demonstratded that red wine polyphenols reduce the susceptibility of low-density lipoproteins to oxidation. Oxidation of LDL is believed to contribute to the development of atherosclerosis.

A strong body of science has reported that grape juice can reduce the oxidation of LDL cholesterol.

In a double blind crossover study[11] 17 men and three women with previously diagnosed heart disease were randomly assigned to drink either placebo or purple grape juice for 14 days. Grape juice drinkers had HDL levels of 50 mg/dL, compared with almost 45 mg/dL in the placebo group. An HDL level below 40 mg/dL is considered a risk factor for heart disease. The grape juice group also had lower levels of two indicators of inflammation: superoxide and soluble CD40 ligand. Inflammation plays a key role in atherosclerosis.

Thirty-two hemodialysis patients were randomly assigned to receive supplements of vitamin E and/or the red grape juice, a placebo, or no supplementation for two weeks[12]. At the end of the study only the red grape juice supplement was associated with lower blood levels of total cholesterol and apolipoprotein B (apoB). ApoB is the main apolipoprotein of LDL cholesterol and is responsible for the transport of cholesterol to tissues. In high concentrations it has been linked to plaque formation in the blood vessels, although the mechanism behind this is not clear. Furthermore, the red grape juice also increased HDL cholesterol levels.

The same researchers[13] report in the same journal in 2006 initial results of their studies with the red grape juice. Both healthy and hemodialysis patients were used in that earlier study, and the researchers reported that, in addition to reductions in markers of inflammation levels of plasma monocyte chemoattractant protein 1 (MCP-1), an inflammatory biomarker associated with CVD, were reduced by 56 per cent at the end of the supplementation period.

Cacao beans are used as an ingredient in cocoa and chocolate and are known to be rich in polyphenols, such as catechin, epicatechin, procyanidin B2 (dimer), procyanidin C1 (trimer), cinnamtannin A2 (tetramer), and other oligometric procyanidins. Cacao polyphenols can decrease LDL cholesterol levels, inhibit LDL cholesterol oxidation[24-25], and increase HDL cholesterol[26].

Recent comparative, double-blind study demonstrated that daily intake of cocoa powder at a dosage of >13 g per day for 4 weeks contributed to a reduction in LDL cholesterol, an elevation in HDL cholesterol, and the suppression of oxidized LDL[27].

The LDL cholesterol-lowering effect in plasma has been demonstrated for various polyphenols, including tea catechins, genistein, daizein, naringenin, hesperetin, and polyphenols in red wine. These polyphenols have the ability to:

• inhibit cholesterol absorption in the digestive tract
• inhibit LDL biosynthesis by lowering the activity and expression of hydroxymethylglutaryl-CoA synthase, hydroxymethylglutaryl-CoA reductase, acyl CoA:cholesterol acyltransferase, and microsomal transfer protein in the liver
• suppress hepatic secretion of apolipoprotein B100
• increase expression of LDL receptors in the liver

The study, published in the Annals of Internal Medicine, provides evidence that virgin olive oil increases the level of substances in the body that prevent the oxidation of LDL cholesterol[44]. First-pressed extra virgin olive oil contains appreciable amounts of polyphenolic compounds, which have inhibited the oxidation of LDL. Extra virgin olive oil also contains other antioxidants, such as tocopherols and flavonoids, which may account for some of its beneficial effects.

Another randomized controlled trial[58] supports the hypothesis that virgin olive oil consumption is effective in protecting LDL from oxidation and in rising HDL cholesterol levels.

Flaxseed's actions as a bulking agent may be its main effect on lipids. However, evidence for its efficacy in cholesterol lowering is limited to small, short-term, poor quality, mainly case and cohort studies with small or nonsignificant effects on cholesterol levels[46-49].

In recent double-blind, randomized, controlled study [45] consumption of 40 g per day of ground flaxseed in baked goods resulted in lowered LDL. However, the effect was modest and short lived. In addition, flaxseed was associated with lower HDL cholesterol, which warrants further attention.

In another recent 2008 study, conducted by researchers from Oklahoma, Arkansas, and Florida, three months of dietary supplementation with flaxseed, 30 g/d, lowered the total and LDL cholesterol levels of Native American postmenopausal women by approximately 7% and 10%, respectively[50].

There is not enough reliable data available to determine whether flaxseed is effective for heart conditions.

In short-term study[51] of people with moderately high cholesterol levels, after seven days on the diet that included avocados, they had significant decreases in total cholesterol and LDL cholesterol, along with an 11% increase in HDL cholesterol.

A randomized study[52] done in Australia has found that a diet rich in avocados lowered total cholesterol by 8.2% compared to 5% for a low fat diet.

There is not enough reliable data available to determine cholesterol lowering effects of avocado.

Allicin is the bioactive compound in garlic that inhibits cholesterol synthesis in vitro. However, numerous studies have produced conflicting results regarding garlic's ability to lower blood cholesterol. So, cholesterol lowering potential of garlic remains unproven.

The older studies on garlic and garlic supplements looked pretty positive. Positive findings in 3 trials[1-3] exhibited a lowering of cholesterol in the range of 6.1% to 11.5%, primarily due to the lowering of low-density lipoproteins. One 12-week study tested the use of garlic powder in ambulatory patients, finding a 14% reduction of serum cholesterol.

More recently, however, several double-blind trials[4-7] have yielded neutral or conflicting results. A pretty well-done study of about 192 adults which looked at the use of garlic — raw garlic, an extract which was a powdered form and then another extract of garlic which was a standardized preparation and a placebo — four different groups in that study. And really what that study showed was no benefit on cholesterol from garlic.

Based on these findings, the use of garlic should not be considered a primary approach to lowering high cholesterol. However, garlic is known to act as a blood thinner and may reduce other risk factors for heart disease. For these reasons, eating garlic may be beneficial for the heart and cardiovascular system.

Based on its soluble fiber content alone, rice bran should have less cholesterol-lowering effect than other sources of fiber. However, rice bran is 12-23% oil, a relatively high percentage compared to most other bran sources, and the oil has an unusually high unsaponifiable matter concentration (4.2%). Rice bran oil, possibly because of this unsaponifiable fraction or its fatty acid content, lowers cholesterol levels in hamsters, rats, nonhuman primates, and humans.

Full-fat rice bran was compared with oat bran and a rice starch placebo in hyperlipidemic people to see if it might have a role in the treatment of hyperlipidemia[9]. Moderately hypercholesterolemic (5.95-8.02 mmol/L), nonsmoking, nonobese adults were studied in a 6-week, randomized, double-blind trial. Researchers found that full-fat rice bran produces significant cholesterol reduction and improvement in the LDL-C:HDL-C ratio in 78% participants. There was no significant difference between the effectiveness of the rice bran and oat bran products used in this study to reduce serum cholesterol or between responses in men and women.

A human study[57] in which brown rice affected nutrient absorption did not show cholesterol reduction.

A preliminary new study[10] shows that people with diabetes who drank pomegranate juice for three months had a lower risk of atherosclerosis. In addition, the pomegranate juice appeared to slow the absorption of unhealthy LDL cholesterol by immune cells.

Note: There is some concern that pomegranate juice may affect metabolism of some prescription medications. It may also cause blood pressure to become too low when combined with certain blood pressure medications.

There is strong scientific evidence from human trials that omega-3 fatty acids from fish or fish oil supplements (EPA + DHA) significantly reduce blood triglyceride levels. Benefits appear to be dose-dependent.

Although fish oil is able to reduce triglycerides, beneficial effects on blood cholesterol levels are small and of uncertain clinical importance. Fish oil supplements appear to cause small improvements in high-density lipoprotein; however, increases (worsening) in low-density lipoprotein levels have also been observed.

Most evidence supports that omega-3 fatty acids inhibit hepatic triglyceride synthesis, decrease Very low-density lipoproteins (VLDL) production/secretion and increase VLDL metabolism, potentially increasing the conversion of VLDL particles to LDL particles. Overall, despite a potential increase in LDL cholesterol levels, many studies have reported that omega-3 fatty acids reduces non-HDL cholesterol (total cholesterol minus HDL cholesterol), which may be a better predictor of atherosclerotic coronary heart disease risk than LDL cholesterol alone.

Two randomized, double-blind, placebo-controlled clinical trials demonstrated that P-O3FA reduced triglycerides by 40-45%[53-54]. In addition, P-O3FA treatment was also associated with a 29-32% reduction in VLDL cholesterol, a 20% reduction in the total cholesterol:HDL cholesterol ratio, and a 6-13% increase in HDL cholesterol. LDL cholesterol increased by 17-32%.

Data on onions for lipoprotein improvement is based primarily on animal studies[21-22].

Researchers from U.S. Department of Agriculture studied the effect of the blueberry compounds on rat liver cells. Pterostilbene showed the most potent effect in stimulating a receptor protein in the cells which plays an important role in lowering cholesterol and other blood fats. This is similar to the way the commercial cholesterol-lowering drug ciprofibrate works. This study claims that blueberries are particularly efficient at reducing cholesterol in a laboratory.

A - Strong scientific evidence. Reliable and relatively consistent scientific data showing a substantial health benefit.

B - Good scientific evidence.

C - Unclear or conflicting scientific evidence. Insufficient data, or low-quality studies suggesting a health benefit or minimal benefit.