The U.S. Preventive Services Task Force (USPSTF) has issued recommendations against the use of two nutritional supplements to prevent cardiovascular disease and cancer. They are beta-carotene and vitamin E. Specifically, beta-carotene even has the risk of causing cancer. This guide has caused a stir. Is it a waste of money and harmful to buy health supplements?
No Benefit in Taking Beta-Carotene or Vitamin E Supplements
Cardiovascular diseases and cancer are leading causes of death in many countries, and inflammation and oxidative stress in the body have been shown to trigger these diseases. The perceived anti-inflammatory and antioxidant effects of taking nutritional supplements are one of the reasons people buy them.
However, in an updated guideline published in The Journal of the American Medical Association, the USPSTF states:
- Vitamin E supplementation is not beneficial in the prevention of cardiovascular disease or cancer. Its excessive supplementation increases the risk of hemorrhagic stroke.
- Beta-carotene supplementation can do more harm than good. Especially for smokers and workers exposed to asbestos, beta-carotene supplements increase the risk of cardiovascular disease mortality and lung cancer.
The combination of beta-carotene and vitamin A supplements also increases the risk of lung cancer.
Beta-Carotene-Foods Fight Cancer, Beta-Carotene Supplements Do the Opposite
Many studies have found that beta-carotene has strong antioxidant effects and that consumption of fruits and vegetables can help reduce the risk of cardiovascular disease, total cancer and all-cause mortality. Among others, foods containing carotenoids may have protective effects against lung, oral cavity, pharynx, and larynx cancers.
However, smokers who take beta-carotene supplements to prevent lung cancer are likely to experience the opposite effect.
Studies have found that taking high doses of beta-carotene supplements increases the risk of lung cancer, and the risk of cancer is highest among smokers. In as early as 1994, a study published in The New England Journal of Medicine showed that the total mortality rate of male smokers taking beta-carotene was 8 percent higher than that of non-smokers, and the causes of death were mostly lung cancer and ischemic heart disease.
So how much supplementation is considered “high dose”? A 2010 meta-analysis showed that people who were supplemented with 20 to 30 mg of beta-carotene daily had a significant 16 percent increase in lung and stomach cancers, with the highest risk among smokers and workers exposed to asbestos.
Moreover, independent of the tar and nicotine content of cigarettes, smokers who take beta-carotene supplements are at increased risk of lung cancer. If smokers consume alcohol on a regular basis, the combination of beta-carotene and ethanol can lead to hepatotoxicity.
Why do beta-carotene from food and beta-carotene supplements produce almost completely opposite results in the body? Memorial Sloan Kettering Cancer Center suggests that dietary-acquired beta-carotene may interact with other phytochemicals in fruits and vegetables to have better effects on the body than supplements.
Other studies suggest that high doses of beta-carotene supplements may change from “antioxidants” to “pro-oxidants” and, in smokers, they may even cause DNA oxidative damage, making cells more susceptible to cancer.
A 2020 review published in Antioxidants pointed out that the interactions of carotenoids in humans, including beta-carotene, are complex, and they can become either antioxidants or pro-oxidants. In the latter case, carotenoids may even damage cells.
As for vitamin A supplements, although they are not as risky as beta-carotene, supplementation through diet is also recommended.
Two studies conducted in 2019 found that dietary intake of vitamin A, rather than supplements, reduces all-cause mortality and cardiovascular disease mortality, and that diets rich in carotenoids, which are converted to vitamin A in the body, are beneficial for cardiometabolic health.
Vitamin A is a fat-soluble nutrient, and the intake of a single supplement may cause it to accumulate in the body in excess. According to the USPSTF, too much vitamin A can reduce bone mineral density or produce hepatotoxic or teratogenic effects.
Are Supplements a Harmful Waste of Money?
The new guideline from the USPSTF also states that there is insufficient evidence to prove that supplementation with a single or multiple nutrients can prevent cardiovascular disease or cancer.
The guideline evaluated the benefits of single or combined vitamin supplements such as beta-carotene, vitamin A, vitamin E, vitamin D, calcium, vitamin C, folic acid, vitamin B12, vitamin B3, vitamin B6 and selenium for the prevention of cardiovascular disease and cancer and for the reduction mortality. And it came to the aforementioned conclusions.
In an editorial accompanying the guideline, Jeffrey A. Linder, MD, chief of general internal medicine at Northwestern University’s Feinberg School of Medicine, along with his colleagues, stated that instead of spending money on and paying attention to supplements, low-risk, high-impact activities should be emphasized. Examples include a healthy diet, exercise, maintaining a healthy weight, and avoiding tobacco use.
It makes people wonder if buying health supplements is really a waste of money and harmful to their bodies. After all, not everyone can enjoy a well-balanced meal on a regular basis.
In this regard, Titan Lin, nutritionist and CEO of Learneating Co. Ltd, said that the intake of a single nutrient supplement often involves high doses; but supplementing a combination of vitamins is much safer.
On the other hand, a balanced diet can indeed reduce cancer and cardiovascular risks, and eating natural foods can supplement multiple nutrients at the same time.
However, some nutrients are more difficult to obtain in effective doses from food, such as fish oil, and can therefore be supplemented with supplements.
There are also a number of factors that make it necessary for people to obtain essential nutrients from supplements.
USPSTF recommends that pregnant women take a daily supplement of 0.4 to 0.8 mg (400 to 800 mcg) of folic acid to prevent congenital neural tube defects in infants.
Lack of vitamin B12 can affect memory, but vitamin B12 is mostly found in animal-based foods. And long-term vegetarians are prone to vitamin B12 deficiencies and need to take supplements.
In addition, the supplementation of astaxanthin, sesamin, gamma-aminobutyric acid (GABA), and other non-essential nutrients still brings some benefits.
If it is relatively difficult to obtain them from food, we can also choose supplements. For instance, people who are stressed and have poor sleep quality can supplement sesamin and GABA; and people who work too much and have sore eyes can supplement astaxanthin.
Lin pointed out that the advantage of vitamin and other nutrient supplements is that they can quickly supplement the needed effective doses, or when people really have difficulty improving their diet, they can get the nutrients they need from supplements.
However, he stressed that “you can’t think that you don’t have to have a balanced diet if you take supplements.”
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