Atherosclerosis, often known as hardening of the arteries, leads to cardiovascular disease, and is the leading cause of death in men over age 35 and all people over 45. Most
are due to atherosclerosis. Although the origin of this condition is not completely understood, we know that it is accelerated by factors such as
(high blood pressure),
and milder forms of impaired glucose tolerance,
, physical inactivity, and
. Chronic inflammation in the body (of various types) is also hypothesized to play a role.
Current theories suggest that atherosclerosis begins with injury to the lining of the arteries. High blood pressure physically stresses this lining, while circulating substances such as low-density lipoprotein (LDL) cholesterol, homocysteine, free radicals, and nicotine chemically damage it. White blood cells then attach to the damaged wall and take up residence. Then, for reasons that are not entirely clear, the artery lining begins to accumulate cholesterol and other fats. Platelets also latch on, releasing substances that cause the formation of fibrous tissue. The overall effect is a thickening of the artery wall called a fibrous plaque.
Over time, the thickening increases, narrowing the bore of the artery. When blockage of the coronary arteries (the arteries supplying the heart) reaches 75% to 90%, symptoms of
develop. In the lower legs, blockage of the blood flow leads to leg pain with exercise, a condition called
Blood clots can develop on the irregular surfaces of arteries and may become detached and block downstream blood flow. Fragments of plaque can also detach. Heart attacks are generally caused by such blood clots, whereas strokes are more often caused by plaque fragments or gradual obstruction. Furthermore, atherosclerotic blood vessels are weak and can burst.
With a disease as serious and progressive as atherosclerosis, the best treatment is prevention. Conventional medical approaches focus on lifestyle changes, such as increasing
, reducing the consumption of saturated fats, and quitting smoking. The regular use of
also appears to be quite helpful by preventing platelet attachment and blood clot formation. If necessary, drugs may be used to lower cholesterol levels or blood pressure.
Principal Proposed Natural Treatments
This section presents some promising and not-so-promising natural approaches for preventing cardiovascular disease by fighting atherosclerosis. Note that we have left out two classes of treatments: those that reduce elevated
. These are discussed in their own articles. It has also been suggested that reducing levels of
might reduce cardiovascular disease risk, a subject also discussed in a separate article. In addition, other sections of this database contain articles on several conditions caused by atherosclerosis, such as
Omega-3 Fatty Acids
Omega-3 fatty acids are healthy fats, found in certain foods such as cold-water fish. Some evidence suggests
might help fight atherosclerosis. However, study results on fish or fish oil for cardiovascular disease have yielded contradictory results.
A 2002 review of many studies on the subject concluded that when all the evidence is put together, it appears that fish or fish oil can slightly reduce overall mortality, heart disease mortality, and sudden cardiac death (heart stoppage due to arrhythmia).
However, a subsequent comprehensive review published in 2004 included additional studies and came to a more pessimistic conclusion.
According to the authors, working for the prestigious Cochrane Collaboration, "It is not clear that dietary or supplemental omega-3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population."
And a 2012 review of 14 randomized, controlled trials involving over 20,000 people further questions the supplement's value in patients with cardiovascular disease. 228 Researchers concluded that omega-3 fatty acids (ranging from 0.4-4.8 g/day) were no better than placebo at reducing rates of cardiovascular events or cardiovascular-related death.
A gigantic study (over 18,000 participants) published in 2007 was widely described in the media as finally proving beyond a shadow of a doubt that fish oil helps prevent heart problems.
Unfortunately, this study lacked a placebo group, and therefore failed to provide reliable evidence.
If it does provide benefit for atherosclerosis, fish oil is thought to do so primarily by reducing serum
. Like cholesterol, triglycerides are a type of fat in the blood that tends to damage the arteries, leading to heart disease. According to most, but not all studies, fish oil can modestly reduce triglyceride levels.
However, the standard drug, gemfibrozil, appears to be more effective than fish oil for this purpose.
The most important omega-3 fatty acids found in fish oil are called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA may have different effects on triglycerides, but as typical for studies involving marginally effective treatments, study results are not consistent; some found EPA more effective than DHA, while others did not find a difference.
A specially-processed, FDA-approved omega-3 product called Omacor (Lovaza) is widely advertised as being more effective than ordinary fish oil in reducing high triglyceride levels. A very large randomized trial, though, did not find evidence to support Omacor in people with diabetes and prediabetes.229 Over 12,000 people with type 2 diabetes or prediabetes were randomized to receive Omacor (1 g) or placebo. All of the study participants had cardiovascular disease or had risk factors for the disease. Six years later at the follow-up, researchers found that there were no differences between the two groups in regards to cardiovascular-related death, heart attacks, strokes, or heart-related hospitalizations and surgeries. The only bright spot was that Omacor did help to reduce high triglyceride levels.
Some but not all studies also suggest that fish, fish oil, or EPA or DHA separately can modestly raise levels of HDL ("good") cholesterol.
Alpha-linolenic acid (ALA) is an omega-3 fatty acid derived from plants. There is some evidence that
, which contains ALA, or whole
may reduce LDL ("bad") cholesterol, perhaps slightly reduce hypertension, and slow down atherosclerosis.
But, a 2010 review of ALA's potential effects on cardiovascular health did not report such promising results.
For example, an analysis of short-term trials (lasting 6-12 weeks) involving healthy adults did not find that ALA improved cholesterol levels. There were also conflicting results pertaining to ALA’s effect on inflammation in the body and glucose metabolism (two possible risk factors for developing heart disease). ALA may, though, offer some protection against nonfatal heart attacks, but there’s no evidence that this type of omega-3 can protect against heart failure, atrial fibrillation, or sudden death.
Finally, while it is commonly stated that people require a certain optimum ratio of omega-3 to
fatty acids in the diet, there is no real evidence that this is true, and some evidence that it is false.
There is no doubt that
will significantly reduce heart disease risk. Increasing
(if you are overweight) will most likely help as well. Although for years there has been an emphasis on reducing fat in the diet, the balance of current evidence indicates that it's more useful to substitute healthy fats (such as the monounsaturated fats in olive oil) for saturated fats than to try to reduce total fat intake.
Evidence suggests that any low-calorie diet, whether low-carb, low-fat, or in-between, will result in weight loss and reduced cardiac risk—provided you stick to it.
However, while it may not be important to cut down on total fat, accumulating evidence hints that trans-fatty acids, a type of fatty acid found in margarine and other hydrogenated oils, increase risk of cardiovascular disease. In July 2002, the US Institute of Medicine concluded that there is no safe intake level of trans-fatty acids and recommended that overall consumption should be kept as low as possible.
The moderate use of alcohol is thought to help reduce cardiovascular risk, but the evidence regarding this subject is both inherently unreliable (because it is based on
) and self-contradictory.
According to the best current evidence available, it appears to be the alcohol in alcoholic drinks that provides benefits rather than, as previously thought, particular substances found in wine.
The optimal intake appears to be about one drink per day for women, and 1-2 drinks per day for men. However, all of these statements are subject to revision, because, as discussed above, they are based on problematic evidence.
Other Proposed Natural Treatments
Several natural products have shown some promise for helping to prevent atherosclerosis.
Garlic is generally said to produce several effects that together reduce atherosclerosis risk.
Although garlic is no longer believed to strongly reduce cholesterol levels, it may improve cholesterol profiles to a modest extent; in addition, it may mildly lower
levels, as well as protect against free radicals and reduce the tendency of the blood to coagulate.
However, the actual evidence for benefit is quite incomplete.
Garlic preparations have been shown to slow the development of atherosclerosis in rats, rabbits, and human blood vessels, reducing the size of plaque deposits by nearly 50%.
Furthermore, in a double-blind, placebo-controlled study that followed 152 individuals for 4 years, standardized garlic powder at a dosage of 900 mg per day significantly slowed the development of atherosclerosis as measured by ultrasound.
Unfortunately, this study suffered from some significant statistical problems.
of 200 people suggests that garlic protects the arteries in other ways as well.
The study measured the flexibility of the aorta, the main artery exiting the heart. Participants who took garlic showed less evidence of damage to their arteries. However, observational studies are notoriously unreliable.
Finally, in another study, 432 people who had suffered a heart attack were given either garlic oil extract or no treatment over a period of 3 years.
The results showed a significant reduction of second heart attacks and an approximately 50% reduction in death rate among those taking garlic. Unfortunately, the researcher's failure to use a
in this trial greatly decreases the meaningfulness of the results.
For more information, including dosage and safety issues, see the full
Other Potentially Beneficial Treatments
red yeast rice
has shown promise for reducing cholesterol levels. A double-blind study performed in China compared red yeast rice against placebo in almost 5,000 people with heart disease.
Over a four-year study period, use of the supplement reportedly reduced heart attack rate by about 45% as compared to placebo and total mortality by about 35%. However, these levels of reported benefit are so high that they raise questions about the study’s reliability.
is a substance obtained from the intestines of pigs. In one study, 200 mg per day of mesoglycan significantly slowed the rate of thickening of arteries.
After 18 months of treatment, the additional layering of the inside vessel lining was 7.5 times less in the group receiving mesoglycan than in the group that did not receive any treatment. However, because this was not a double-blind, placebo-controlled trial, the results can't be taken as truly reliable. Preliminary evidence suggests that this supplement may work in several ways: supplying material for repair of arteries, "thinning" the blood, and improving cholesterol levels.
also appears to be helpful. In a 6-month, double-blind, placebo-controlled study, 187 individuals with
were given either 365 mg of magnesium daily or placebo.
The results showed that use of magnesium significantly improved exercise capacity, lessened exercise-induced chest pain, and improved general quality of life. Additionally, magnesium may reduce the atherosclerosis risk caused by hydrogenated oils, margarine-like fats found in many "junk" foods.
Mildly impaired responsiveness to insulin (short of outright diabetes) is a fairly common condition that appears to increase the risk of heart disease.
supplementation might restore normal insulin responsiveness, as well as aid in
and possibly improve
levels. The net result might be decreased risk of heart disease. In support of this theory, an observational trial found associations between higher chromium intake and reduced risk of heart attack.
Some but not all observational studies suggest that
might help prevent heart disease.
has shown inconsistent promise as well.
contains some of the same active ingredients as tea, and on this basis, it is sometimes mentioned as a potentially heart-healthy food.
Many herbs and supplements appear to decrease platelet stickiness, including
. Whether this translates into an actual benefit for preventing atherosclerosis remains unknown.
Indirect evidence suggests that
might help prevent heart disease, especially in men.
Frequent consumption of nuts may reduce the risk of heart disease,
probably because the monounsaturated fats in nuts reduce cholesterol levels.
Wholegrain oats may help prevent heart disease, but the supporting evidence is almost entirely limited to studies conducted by manufacturers of wholegrain oat products.
There is little to no evidence of benefit for other whole grains because studies have not been performed.
For other natural substances that may help prevent atherosclerosis by lowering its major risk factors, see the articles on
. For natural substances that may be helpful for
of atherosclerosis, see the articles on
Congestive Heart Failure
, a technique that involves intravenous administration of the substance EDTA, is widely promoted in some alternative medicine circles as a treatment for atherosclerosis. However, there is no meaningful evidence that it works, and growing evidence that it does not work.
Antioxidants: Probably Not Effective
The body is engaged in a constant battle against damaging chemicals called free radicals, or pro-oxidants. These highly reactive substances are believed to play a major role in atherosclerosis, cancer, and aging in general.
To counter the harmful effects of free radicals, the body manufactures
to chemically neutralize them. However, the natural antioxidant system may not always be equal to the task. Sources of free radicals, such as cigarette smoke and smoked meat, may overwhelm this defense mechanism.
Certain dietary nutrients augment the body's natural antioxidants and may be able to help out when the primary system is under stress. Vitamins E and C and beta-carotene are the best known, but many other substances found in fruits and vegetables are also strong antioxidants. For years we've been thinking that antioxidant supplements might offer considerable protection against heart disease, especially vitamin E. However, current evidence appears to dampen these high expectations.
Before presenting this disappointing information, it is necessary to explain the weaknesses of the observational studies that raised our hopes.
are relatively inexpensive and are often used to evaluate the potential health benefits of nutrients such as antioxidants. This type of study follows large groups of people for years and keeps track of a great deal of information about them, including diet. Researchers then examine the data closely and try to identify which dietary factors are associated with better health and longer life.
However, the results can be misleading. For example, if an observational study finds that people who take vitamin supplements live longer, it is not necessarily the vitamins that deserve the credit. Vitamin users also tend to exercise more and to eat more healthful foods, habits that may play a more important role than the vitamins. It is impossible to know for sure simply by evaluating the results of such a study.
Similarly, several observational studies have found that men who consume more foods that are rich in lycopene are less likely to develop prostate cancer. But does this mean that taking lycopene supplements will reduce prostate cancer risk? Not necessarily. Such foods contain many other nutrients as well, and they may be more important than lycopene.
A more reliable kind of study is the
. In these studies, some people are given a specific substance, such as a vitamin, and then compared to others who are given a placebo (or sometimes no treatment at all). The best intervention trials use a
design. The results of intervention trials are far more conclusive than those of observational studies. In the field of antioxidant therapy for preventing atherosclerosis, observational studies raised hopes, but intervention trials dashed them.
(For more information on why double-blind trials are essential, see
Why Does This Database Rely on Double-Blind Studies?
Most but not all observational studies have found associations between high intake of vitamin E and reduced risk of cardiovascular disease.
However, as noted above, observational studies alone cannot be relied upon to identify useful treatments. Intervention trials, which provide much more convincing evidence of effectiveness, have overall failed to find vitamin E supplements effective.
The Heart Outcomes Prevention Evaluation (HOPE) trial found that natural vitamin E (d-alpha-tocopherol) at a dose of 400 IU daily did not reduce the number of heart attacks, strokes, or deaths from heart disease any more than placebo.
The details of this well-designed, double-blind trial were published in the January 20, 2000, issue of
The New England Journal of Medicine
. The trial followed more than 9,000 men and women who had existing heart disease or were at high risk for it.
In addition, a large open trial compared the effectiveness of aspirin and vitamin E for the prevention of heart attacks, strokes, and other diseases related to atherosclerosis.
While aspirin treatment proved somewhat helpful, vitamin E produced little to no benefit.
Negative results have been seen in other large trials as well.
A few have even found weak indications that use of vitamin E may worsen certain outcomes.
When the results of these studies began to come in, some antioxidant proponents suggested that the individuals enrolled in these trials already had too advanced disease for vitamin E to help. However, a large trial found vitamin E ineffective for slowing the progression of heart disease in healthy people, as well.
Moreover, in an extremely large placebo-controlled trial involving over 14,000 US male physicians at low risk for heart disease, 400 IU of vitamin E every other day failed to lower the risk of major cardiovascular events or mortality over a period of 8 years.
On the contrary, vitamin E was associated with a slightly increased risk of stroke.
On balance, the evidence strongly suggests that vitamin E in the form used in these studies (alpha-tocopherol) is
helpful for preventing heart disease.
It has been suggested that another form of vitamin E, gamma-tocopherol might be more helpful than alpha-tocopherol.
Gamma-tocopherol is present in the diet much more abundantly than alpha-tocopherol, and it could be that the studies showing benefits with dietary vitamin E actually tracked the influence of gamma-tocopherol.
However, an observational study specifically looking to see if gamma-tocopherol levels were associated with risk of heart attack found no relationship between the two.
Nonetheless, intervention trials of gamma-tocopherol are currently underway.
For more information, including dosage and safety issues, see the full
The study results involving
are interesting. Beta-carotene is one member of a large category of substances in foods known as
which are found in high levels in yellow, orange, and dark green vegetables.
Many studies suggest that eating foods high in carotenoids can prevent atherosclerosis.
However, isolated beta-carotene in supplement form may not help, and could actually increase your risk, especially if you consume too much alcohol.
A huge, double-blind intervention trial involving 29,133 Finnish male smokers found 11%
deaths from heart disease and 15% to 20%
strokes in those participants taking beta-carotene supplements.
This certainly does not encourage one to take it.
Similar poor results with beta-carotene were seen in another large, double-blind study in smokers.
Furthermore, beta-carotene supplementation was also found to increase the incidence of angina in smokers.
What is happening here? Clearly, smoking presents a challenge to antioxidants. However, the question remains: Why should beta-carotene not only fail to help but actually worsen the situation?
One possible explanation is that beta-carotene in the diet always comes along with other naturally occurring carotenes. It is quite likely that other carotenoids in the diet are equally or more important than beta-carotene alone.
Taking beta-carotene supplements may actually promote deficiencies of other natural carotenes,
and overall that may hurt more than it helps.
The moral of the story is that you should eat your vegetables but maybe not take beta-carotene supplements.
A single, double-blind study suggests that the antioxidant
may help prevent the progression of atherosclerosis after a heart attack.
vitamins, supplements, and herbs have been suggested as preventive treatments for atherosclerosis, including
from grape seed or pine bark,
from red wine and grape skins. However, although a number of interesting studies have suggested that these substances may be beneficial, the state of the evidence is still too preliminary to draw any conclusions.
Like other berries,
contains high levels of natural antioxidants. It has been widely advertised as effective for preventing heart disease, but the studies upon which this claim is based are far too preliminary to prove anything at all.
One large, double-blind study explored the potential benefit of
for preventing cardiovascular problems in women at high risk for them, but failed to find benefit.
And, in an extremely large placebo-controlled trial involving over 14,000 US male physicians at low risk for heart disease, 500 mg of vitamin C daily did not lower the risk of major cardiovascular events or mortality over a period of 8 years.
It has been suggested that the best approach is to use a combination of antioxidants. This makes sense theoretically because, for example, vitamin E fights free radicals that dissolve in fats while vitamin C fights those that dissolve in water. However, evidence for benefit with such combinations comes only from observational studies.
A 3-year, double-blind, placebo-controlled study of 160 individuals found no benefit with combined antioxidant treatment providing vitamin E (800 IU), vitamin C (1,000 mg), beta-carotene (25 mg), and selenium (100 mcg).
Similarly, a 3-year, double-blind, placebo-controlled study of 423 menopausal women with
coronary artery disease
found no benefit with combined vitamin E (800 IU daily) and vitamin C (1000 mg daily).
Furthermore, a 7-year, double-blind, placebo-controlled study of more than 13,000 French men and women failed to find any significant reduction of cardiovascular disease rates through use of a daily supplement containing 120 mg of vitamin C, 30 mg of vitamin E, 6 mg of beta-carotene, 100 mcg of selenium, and 20 mg of zinc.
A review of 50 randomized trials consisting of 294,478 patients evaluated prevention of cardiovascular disease with vitamins A, B6, B12, C, D, E; folic acid; beta-carotene; and selenium. There was no significant association between vitamin and antioxidant supplementation and risk of cardiovascular death, myocardial infarction, stroke, transient ischemic attack, or angina.230