Antioxidant supplements: do they work?

December 16, 2008 by  

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Resource post for December

In an era when people are becoming more and more health-conscious, vitamin pills are becoming more and more popular. Millions of people are swallowing vitamin supplement pills everyday, believing that these medications are beneficial to their health, especially their hearts. These supplements range from vitamin cocktails to omega-3’s to antioxidants. These “power pills” or “health supplements” are supposed to keep our body strong and healthy and prevent a wide range of diseases, from heart disease to high blood pressure, from aging to cancer.

In this resource post, I am reviewing the recent updates on vitamin and antioxidant supplementation and answer the question: Do we really need them?

Vitamin supplements

A 2007 meta-analysis by Bjelakovic and colleagues on vitamin supplements came up with surprising results: not only are the benefits of antioxidants suspect, they can actually increase overall mortality. A group of researchers analysed data from clinical trials which used supplementation of the antioxidants vitamin A, vitamin E, beta-carotene, vitamin C and selenium used as stand-alone supplements or in combination in people with a variety of health conditions. The results showed that most of these vitamins actually do not have a discernable health benefits to those who took them. Furthermore, vitamins A and E and beta-carotene (but not Vitamin C) and selenium can actually result in increased mortality.

Based on their results, Bjelakovic and colleagues discourages the use of synthetic vitamin supplements. Instead, we should go for the natural sources of these vitamins – fresh fruits, vegetables and nuts.

Antioxidant supplements

In a more recent review paper, the same researchers evaluated several clinical trials involving over 200,000 people which compared the efficacy of antioxidant supplements versus placebo in the primary and secondary prevention of cardiovascular gastrointestinal, neurological, ocular, dermatological, rheumatoid, renal, and endocrinological disorders

The authors reported that:

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

Folic acid and vitamin B

It has always been a popular belief that folic acid and vitamin B can protect us from the monsters which are heart disease and stroke by reducing the levels of the amino acid homocysteine in the blood. Homocysteine is believed to be a biomarker for cardiovascular diseases. Unfortunately, the results of this long-term trial seem to cast doubts on the homocysteine theory.

The trial included more than 5,400 U.S. women who were health professionals. Some had a history of cardiovascular disease, and others had three or more coronary risk factors, such as high blood pressure, obesity or diabetes. Half of the women took a daily combination pill containing 2.5 milligrams of folic acid, 50 milligrams of vitamin B6, and 1 milligram of vitamin B12, while the other half took a placebo.”

These women were “blinded” – that means they didn´t know whether they were taking vitamins or placebo – and followed-up for more than 7 years. The results of the trial were a bit disappointing. 14.9% of those who took the vitamin pills had at least 1 cardiovascular event, such as a heart attack or stroke. 14.3% of those who were given placebo also had at least 1 cardiovascular event within the same period of time. The difference between the 2 groups was not significant.

The study results had important implications, namely:

  • The homocysteine – cardiovascular link needs to be re-examined; homocysteine may not be an appropriate biomarker for cardiovascular disease.
  • Taking folic acid does not prevent cardiovascular disease.
  • Flour in the US and some other countries is fortified with folic acid. Additional supplementation is not necessary except for pregnant women.

Pregnant women are routinely advised to take folic acid supplement to prevent birth defects that can affect the baby´s nervous system, leading to the condition of spina bifida. Natural sources of folic acid are green leafy vegetables and citrus fruits.

Vitamin D and calcium

This trial evaluated the effects of vitamin D and calcium supplements on blood pressure and hypertension risk of healthy women. The study involved 36,252 postmenopausal women who were followed up for about 7 years. The results show that

“the precision of this study excludes a BP-lowering effect of calcium supplementation of clinical or public health importance…[the analysis] “is strongly suggestive of an absent relationship between vitamin D intake and hypertension”

Selenium and Vitamin E

A more recent development comes from the large-scale study called SELECT (Selenium and Vitamin E Cancer Prevention Trial) which assessed whether selenium and vitamin E supplements can prevent prostate cancer as suggested by earlier studies. Recently, about 5 years into the study, the National Cancer Institute (NCI) decided to stop the study due to lack of preventive effects as well as”concerning” findings that showed a slight increase risk of developing prostate cancer among those who took vitamin E and diabetes among those who took selenium. Even though the “slight increased risks” observed in this study of 35,000 healthy men were not statistically significant, they are risks that couldn’t be ignored.

What the experts have to say

The American College of Cardiology and American Heart Association (AHA) do not recommend the use of antioxidant supplements as specified in 2002 Guideline Update in for the management of chronic angina. In 2005, the AHA science advisory board issued that statement that “scientific data do not justify the use of antioxidant vitamin supplements” in the prevention of cardiovascular diseases.

“… in agreement with many in the field, we conclude that the existing scientific database does not justify routine use of antioxidant supplements for the prevention and treatment of CVD.25-28,29 This conclusion is consistent with theAmerican College of Cardiology/American Heart Association 2002 Guideline Update for the management of patients with chronic stable angina, which states that there is no basis for recommending that patients take vitamin C or E supplements or other antioxidants for the express purpose of preventing or treating coronary artery disease…”


Vitamins and minerals are essential for our health. But we have to be careful about our sources of essential nutrients. In spite of all the claims of these supplements, they are no substitute to the natural fresh fruits, vegetables, and nuts as well as a healthy lifestyle.


Photo credit: stock.xchng

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4 Responses to “Antioxidant supplements: do they work?”
  1. Thanks for this very informative article, you definitely know you stuff. Many people don’t know the proper supplements to take and this article can definitely point people in the right direction.

  2. BSN Health says:

    Very useful information on Antioxidant supplements. Now a days, millions of people are swallowing vitamin supplements such as antioxidants to get their good health. For BSN health supplements information visit once.

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