The US Preventive Services Task Force (USPSTF) has issued recommendations against the use of two dietary supplements to prevent cardiovascular disease and cancer. They are beta-carotene and vitamin E. Beta-carotene in particular even has the risk of causing cancer. This guide has caused a stir. Is it a waste of money and harmful to buy supplements?
No benefit of taking beta-carotene or vitamin E supplements
Cardiovascular disease and cancer are the 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 supplements is 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 preventing 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 deaths from cardiovascular disease and lung cancer.
The combination of beta-carotene and vitamin A supplements also increases the risk of lung cancer.
Beta-carotene foods fight cancer, while beta-carotene supplements do the opposite
Many studies have shown that beta-carotene has powerful antioxidant effects and that eating fruits and vegetables can help reduce the risk of cardiovascular disease, all-cause cancer, and all-cause mortality. Foods containing carotenoids can have protective effects against lung, oral cavity, throat and larynx cancer, among other things.
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 cancer risk is highest in smokers. As early as 1994, a study published in the New England Journal of Medicine showed that the all-cause death rate of male smokers taking beta-carotene was 8 percent higher than that of non-smokers, and the main causes of death were lung cancer and ischemic heart disease.
So how much supplementation counts as a “high dose”? A 2010 meta-analysis showed that people who received 20 to 30 mg of beta-carotene daily had a significant 16 percent increase in lung and stomach cancer, with smokers and asbestos-exposed workers at highest risk.
In addition, smokers who take beta-carotene supplements have an increased risk of lung cancer, regardless of the tar and nicotine content of cigarettes. If smokers consume alcohol regularly, the combination of beta-carotene and ethanol can lead to hepatotoxicity.
Why do dietary beta-carotene and beta-carotene supplements produce almost completely opposite results in the body? The Memorial Sloan Kettering Cancer Center advises that dietary beta-carotene can interact with other phytochemicals in fruits and vegetables to have a better effect on the body than supplements.
Other studies suggest that high doses of beta-carotene supplements can switch from “antioxidants” to “prooxidants” and even cause oxidative DNA damage in smokers, making cells more susceptible to cancer.
A 2020 review published in Antioxidants indicated that the interactions of human carotenoids, including beta-carotene, are complex and they can become either antioxidants or pro-oxidants. In the latter case, carotenoids can even damage cells.
As for vitamin A supplements, supplementation is also recommended, although they are not as risky as beta-carotene.
Two studies conducted in 2019 found that getting vitamin A through the diet rather than supplements reduced all-cause mortality and mortality from cardiovascular disease, and that a diet high in carotenoids converted to vitamin A in the body be beneficial for cardiometabolic health.
Vitamin A is a fat-soluble nutrient, and taking a single supplement can cause it to accumulate in excess in the body. According to the USPSTF, too much vitamin A can decrease bone mineral density or produce hepatotoxic or teratogenic effects.
Are Diet Supplements a Harmful Waste of Money?
The USPSTF’s new guidance also states that there is insufficient evidence that supplementing with any single or multiple nutrients can prevent cardiovascular disease or cancer.
The guideline evaluates the benefit of individual or combined vitamin preparations 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 diseases and cancer and to reduce mortality. And it came to the above conclusions.
In an editorial accompanying the guideline, Drs. Jeffrey A. Linder, chief physician in general internal medicine at Northwestern University’s Feinberg School of Medicine, along with his colleagues, that instead of spending money on dietary supplements and looking to look for, low-risk, high-impact activities should be emphasized. Examples include eating a healthy diet, exercising, maintaining a healthy weight and avoiding tobacco use.
People wonder if buying supplements is really a waste of money and harmful to their body. After all, not everyone can eat a balanced diet on a regular basis.
In this regard, Titan Lin, nutritionist and CEO of Learneating Co. Ltd said that taking a single supplement often involves high doses; but supplementing a combination of vitamins is much safer.
On the other hand, a balanced diet can actually reduce cancer and cardiovascular risks, and eating natural foods can supplement multiple nutrients at once.
However, some nutrients are more difficult to obtain from food in effective doses, such as: B. fish oil, and can therefore be supplemented with dietary supplements.
There are also a number of factors that make it necessary for people to get essential nutrients from supplements.
USPSTF recommends that pregnant women take 0.4 to 0.8 mg (400 to 800 mcg) of folic acid daily to prevent congenital neural tube defects in infants.
A lack of vitamin B12 can impair memory, but vitamin B12 is mainly found in animal foods. And long-term vegetarians are prone to vitamin B12 deficiency and need to take supplements.
In addition, supplementing with astaxanthin, sesamin, gamma-aminobutyric acid (GABA), and other non-essential nutrients still brings some benefits.
If it is relatively difficult to get them from food, we can also choose food supplements. For example, 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 dietary supplements is that they can quickly supplement the required effective doses, or if people are really struggling to improve their diet, they can get the nutrients they need from dietary supplements.
However, he emphasized that “one cannot believe that one does not have to eat a balanced diet when taking supplements.”