Atherosclerosis, or hardening of the arteries, is a very common disease of the major blood vessels. It is characterized by fatty streaks along the vessel walls and by deposits of cholesterol and calcium. Atherosclerosis of arteries supplying the heart is called coronary artery disease. It can restrict the flow of blood to the heart, which often triggers heart attacks—the leading cause of death in Americans and Europeans. Atherosclerosis of the arteries supplying the legs causes a condition called intermittent claudication.

People with elevated cholesterol levels are much more likely to have atherosclerosis than people with low cholesterol levels. Many important nutritional approaches to protecting against atherosclerosis are aimed at lowering serum cholesterol levels. People concerned about atherosclerosis should also read the section on cholesterol, particularly regarding specific dietary information.

People with diabetes are also at very high risk for atherosclerosis. Those with diabetes who are concerned about atherosclerosis should also read the section on diabetes. People with elevated triglycerides may be at high risk for atherosclerosis. For a discussion about natural substances that lower triglycerides and may also reduce the risk of atherosclerosis, see the section on high triglycerides.

Obesity and type A behavior (time conscious, impatient, and aggressive) are both associated with an increased risk of atherosclerosis, while exercise is linked to protection from this condition.

The fibers most linked to the reduction of cholesterol levels are found in oats, psyllium seeds, fruit (pectin) and beans (guar gum).⁵ An analysis of many soluble fiber trials proves that a cholesterol lowering effect exists, but the amount cholesterol falls is quite modest.⁶ For unknown reasons, however, diets higher in insoluble fiber (found in whole grains and vegetables and mostly unrelated to cholesterol levels) have been reported to correlate better with protection against heart disease in both men and women.^{7 8} Some trials have used 20 g of additional fiber per day for several months to successfully lower cholesterol.⁹

Independent of their action on serum cholesterol, foods that contain high amounts of cholesterol—mostly egg yolks—can induce atherosclerosis.¹⁰ It makes sense to reduce the intake of egg yolks. However, eating eggs does not increase serum cholesterol as much as eating saturated fat, and eggs may not increase serum cholesterol at all if the overall diet is low in fat. A decrease in atherosclerosis resulting from a pure vegetarian diet (no meat, poultry, dairy or eggs), combined with exercise and stress reduction, has been proven by medical research.¹¹ These and other dietary issues for people with atherosclerosis are discussed in more detail in the section on cholesterol.

Recent preliminary evidence has implicated salt consumption as a risk factor for heart disease and death from heart disease in overweight people,¹² where an increase in salt consumption of 2.3 grams per day was associated with a 44% increase in coronary heart disease mortality, a 61% increase in cardiovascular disease mortality, and a 39% increase in mortality from all causes. Blinded, intervention trials are needed to confirm these preliminary observations.

Nutritional supplements that may be helpful: Many cardiologists agree that LDL—low density lipoproteins, or "bad" cholesterol—triggers atherosclerosis only when it has been damaged by reactive molecules called free radicals. Several antioxidant supplements protect LDL cholesterol.

Vitamin E is an antioxidant that serves to protect LDL from oxidative damage¹³ and has been linked to prevention of heart disease in double-blind research.¹⁴ Many doctors recommend 400–800 IU of vitamin E per day to lower the risk of atherosclerosis and heart attacks. However, some leading researchers suggest taking only 100–200 IU per day as studies that have explored the long-term effects of different supplemental levels suggest no further benefit beyond that amount and research reporting positive effects with 400–800 IU per day have not investigated the effects of lower intakes.¹⁵

A large double-blind trial found no benefit from vitamin E supplementation in the prevention of non-fatal heart attacks among people at high risk.¹⁶ Participants, who had a history of diabetes or existing cardiovascular disease, took 400 IU of natural vitamin E per day for 4.5 years. It is not known why these results so strongly contradict previous findings of a protective effect from vitamin E.^{17 18 19} It is possible the 800 IU per day amount given to some people in one of these earlier studies was responsible for the positive results reported, but more research is needed to resolve the conflicting findings of these large trials.

In some studies, people who consume more selenium from their diet have a lower risk of heart disease.^{20 21} In one double-blind report, individuals who already had one heart attack were given 100 mcg of selenium per day or placebo for six months.²² At the end of the trial, there were four deaths from heart disease in the placebo group but none in the selenium group (although the numbers were too small for this difference to be statistically significant). Some doctors recommend that people with atherosclerosis supplement with 100–200 mcg of selenium per day.

Quercetin, a flavonoid, also protects LDL cholesterol from damage.²³ Several studies have found eating foods high in quercetin lowers the risk of heart disease,^{24 25 26} but the research on this subject is not always consistent²⁷ and some research finds no protective link.²⁸ Quercetin is found in apples, onions, black tea, and as a supplement. In some studies, dietary amounts linked to protection from heart disease are as low as 35 mg per day.

Blood levels of an amino acid called homocysteine have been linked to atherosclerosis and heart disease in most research,^{29 30} though uncertainty remains about whether elevated homocysteine actually causes heart disease.^{31 32} Although some reports have found associations between homocysteine levels and dietary factors such as coffee and protein intakes,³³ evidence linking specific foods to homocysteine remains preliminary. Higher blood levels of vitamin B6, vitamin B12, and folic acid are associated with low levels of homocysteine³⁴ and supplementing with these vitamins lowers homocysteine levels.^{35 36}

For the few cases in which vitamin B6, vitamin B12, and folic acid fail to normalize homocysteine, adding 6 grams per day of betaine (trimethylglycine) may be effective.³⁷ Of these four supplements, folic acid appears to be the most important.³⁸ Attempts to lower homocysteine by simply changing the diet rather than using vitamin supplements have not been successful.³⁹

While several trials have consistently shown that B6, B12, and folic acid lower homocysteine, the amounts used vary from study to study. Many doctors recommend 50 mg of vitamin B6, 100–300 mcg of vitamin B12, and 500–800 mcg of folic acid. Even researchers finding only inconsistent links between homocysteine and heart disease have acknowledged that a B vitamin might offer protection against heart disease independent of the homocysteine-lowering effect.⁴⁰

Experimentally increasing homocysteine levels in humans has led to temporary dysfunction of the cells lining blood vessels. Researchers are concerned this dysfunction may be linked to atherosclerosis and heart disease. Vitamin C has been reported to reverse the dysfunction caused by increases in homocysteine.⁴¹ Vitamin C also protects LDL.⁴²

Despite the protective mechanisms attributed to vitamin C, some research has been unable to link vitamin C intake to protection against heart disease. These negative trials have mostly been conducted using people who consume 90 mg of vitamin C per day or more—a level beyond which further protection of LDL may not occur. Trials studying people who eat foods containing lower amounts of vitamin C have been able to show a link between dietary vitamin C and protection from heart disease. Therefore, leading vitamin C researchers have begun to suggest that vitamin C may be important in preventing heart disease, but only up to 100–200 mg of intake per day.⁴³ Many doctors suggest that people take vitamin C—often 1 gram per day—despite the fact that research does not yet support levels higher than 200 mg per day. See the section on cholesterol for more details.

Though low levels (2 grams per day) of evening primrose oil appear to be without action,⁵⁵ 3–4 grams per day have lowered cholesterol in double-blind research.⁵⁶ Lowering cholesterol levels should in turn reduce the risk of atherosclerosis.

Preliminary research shows that chondroitin sulfate may prevent atherosclerosis in animals and humans and may also prevent heart attacks in people who already have atherosclerosis.^{57 58} However, further research is needed to determine the value of chondroitin sulfate supplements for preventing or treating atherosclerosis.

Resveratrol, found primarily in red wine, is a naturally occurring antioxidant that decreases the "stickiness" of blood platelets and may help blood vessels remain open and flexible.^{59 60 61} Resveratrol research remains very preliminary, however, and as yet there is no clear evidence the levels found in supplements will help in any significant way.

Preliminary evidence suggests that octacosanol may reduce atherosclerosis,⁶² but the significance of this research remains unknown.

In 1992, a Finnish study found a strong link between unnecessary exposure to iron and increased risk for heart disease.⁶³ Since then many studies have not found that link,^{64 65 66} though perhaps an equal number have been able to confirm the outcome of the original report.^{67 68} One 1999 analysis of twelve studies looking at iron status and heart disease found no overall relationship,⁶⁹ though another 1999 analysis of published studies came to a different conclusion.⁷⁰ While the effect of unnecessary exposure to iron, including iron supplements, on the risk of heart disease remains unclear, there is no benefit in supplementing iron in the absence of a diagnosed deficiency.

Like vitamin E, tocotrienols may offer protection against atherosclerosis by preventing oxidative damage to LDL-cholesterol.⁷¹ In a double-blind study in patients with severe atherosclerosis of the carotid artery—the main artery supplying blood to the head—tocotrienol administration (200 mg per day) reduced the level of lipid peroxides in the blood. Moreover, in 7 of 25 patients receiving tocotrienols for 12 months, the size of the atherosclerotic plaques became smaller; in contrast, none of the 25 patients receiving the placebo showed an improvement in their atherosclerosis.⁷²

Herbs that may be helpful: Many actions associated with herbal supplements may help prevent or potentially alleviate atherosclerosis. Herbs such as garlic and ginkgo appear to directly affect the hardened arteries by multiple mechanisms. Herbs such as psyllium, guggul, and fenugreek reduce cholesterol and other lipid levels in the blood, known risk factors for hardened arteries. A related group are herbs, such as green tea, that prevent the oxidation of cholesterol, an important step in protecting against atherosclerosis. Finally, there are herbs such as ginger and turmeric that reduce excessive stickiness of platelets, thereby reducing atherosclerosis.

Garlic has been shown to prevent atherosclerosis in a four year clinical study which found that consumption of 900 mg per day of a garlic supplement standardized to allicin potential was capable of reducing arterial plaque formation by 5–18%.⁷³ The individuals in this study were 50–80 years old and the benefits were most notable in women. This study points to the long-term benefits of garlic to both prevent and possibly slow the progression of atherosclerosis in people at risk.

Garlic has also lowered cholesterol levels in double-blind research,⁷⁴ though more recently, some double-blind studies have not found garlic to be effective.^{75 76 77} Some of the negative studies have flaws in their design.⁷⁸ Nonetheless, the relationship between garlic and cholesterol lowering is somewhat unclear.⁷⁹

Garlic has also been shown to prevent excessive platelet adhesion in humans.⁸⁰ Allicin, often considered the main active component of garlic, is not alone in this action. The constituent known as ajoene has also shown beneficial effects on platelets.⁸¹

Ginkgo may reduce the risk of atherosclerosis by interfering with a chemical the body sometimes makes in excess called platelet activating factor (PAF).⁸² PAF stimulates platelets to stick together too much; ginkgo stops this from happening. Refer to the section on intermittent claudication for an example of how garlic and ginkgo can directly affect an atherosclerosis-induced disorder. Ginkgo also increases blood circulation to the brain, arms and legs.⁸³

Garlic and ginkgo also decrease excessive blood coagulation. Both have been shown in double-blind⁸⁴ or single blind⁸⁵ studies to decrease the overactive coagulation of blood that may contribute to atherosclerosis.

Several herbs have been shown in research to lower lipid levels. Of these, psyllium has the most consistent backing from multiple double-blind studies showing lower cholesterol and triglyceride levels.⁸⁶

Guggul has been less extensively studied but double-blind evidence suggests it can significantly improve cholesterol and triglyceride levels in people.⁸⁷ Numerous medicinal plants and plant compounds have demonstrated an ability to protect LDL cholesterol from being damaged by free radicals. Garlic,⁸⁸ ginkgo,⁸⁹ and guggul⁹⁰ are of particular note in this regard. Garlic and ginkgo have been most convincingly shown to protect LDL cholesterol in humans.

The evidence supporting the ability of fenugreek to lower lipid levels is not as complete, coming from smaller, less complete studies.⁹¹ Preliminary Chinese research found that fo-ti may lower cholesterol levels.⁹²

Since oxidation of LDL cholesterol is thought to be important in causing or accelerating atherosclerosis and green tea protects against oxidation, this herb has a role in preventing atherosclerosis. However, while some studies show that green tea is an antioxidant in humans,⁹³ others have not been able to confirm that it protects LDL cholesterol from damage.⁹⁴ Much of the research documenting the health benefits of green tea is based on the amount of green tea typically drunk in Asian countries—about three cups per day (providing 240–320 mg of polyphenols).

The research on ginger’s ability to reduce platelet stickiness indicates that 10 grams (approximately 1 heaping teaspoon) per day is the minimum necessary amount to be effective.⁹⁵ Lower amounts of dry ginger,⁹⁶ as well as various levels of fresh ginger,⁹⁷ have not been shown to affect platelets.

Turmeric’s active compound curcumin has shown potent anti-platelet activity in animal studies.⁹⁸ It has also demonstrated this effect in preliminary human studies.⁹⁹ In a similar vein, bilberry has been shown to prevent platelet aggregation.¹⁰⁰

Butcher’s broom and rosemary are not well studied as being circulatory stimulants but are traditionally reputed to have such an action that might impact atherosclerosis. While butcher’s broom is useful for various diseases of veins, it can protect arteries, too.¹⁰¹

References:

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46. Phillipson BE, Rothrock DW, Connor WE, et al. Reduction of plasma lipids, lipoproteins, and apoproteins by dietary fish oils in patients with hypertriglyceridemia. N Engl J Med 1985;312:1210–6.

47. Haglund O, Wallin R, Luostarinen R, Saldeen T. Effects of a new fluid fish oil concentrate, ESKIMO-3, on triglycerides, cholesterol, fibrinogen and blood pressure. J Intern Med 1990;227:347–53.

48. Haglund O, Luostarinen R, Wallin W, Saldeen T. Effects of fish oil on triglycerides, lipoprotein(a), atherogenic index and fibrinogen. Influence of the degree of purification of the oil. Nutr Res 1992;12:455–68.

49. Haglund O, Luostarinen R, Wallin R, et al. The effects of fish oil on triglycerides, cholesterol, fibrinogen and malondialdehyde in humans supplemented with vitamin E. J Nutr 1991;121:165–9.

51. Leaf A, Jorgensen MB, Jacobs AK, et al. Do fish oils prevent restenosis after coronary angioplasty? Circulation 1994;90:2248–57.

52. Sacks FM, Stone PH, Gibson CM, et al. Controlled trial of fish oil for regression of human coronary atherosclerosis. HARP Research Group. J Am Coll Cardiol 1995;25:1492–8.

53. von Schacky C, Angerer P, Kothny W, et al. The effect of dietary omega-3 fatty acids on coronary atherosclerosis. A randomized, double-blind, placebo-controlled trial. Ann Intern Med 1999;130:554–62.

54. Sacks FM, Stone PH, Gibson CM, et al. Controlled trial of fish oil for regression of human coronary atherosclerosis. HARP Research Group. J Am Coll Cardiol 1995;25:1492–8.