The US Preventive Services Task Force issued a recommendation statement in June 2022 on the use of over-the-counter vitamin supplements. Based on its independent expert panel’s review of existing scientific evidence, the task force recommended against the use of beta-carotene or vitamin E supplementation for the prevention of cancer and cardiovascular disease, the two leading causes of death in the US. USA
The task force’s new statement is an update to its 2014 recommendation, which reached the same conclusion. In the most recent analysis, the expert panel looked at an additional six randomized controlled trials for beta-carotene and nine for vitamin E.
The Conversation asked Katherine Basbaum, a clinical dietitian specializing in cardiovascular disease, to explain what this recommendation means for the general public, particularly those who are currently taking dietary supplements for cancer and cardiovascular disease prevention, or who are considering taking them. In our Q&A session with Basbaum, she interprets the data behind the task force’s conclusion.
1. What was the basis for the working group’s recommendation?
The US Preventive Services Task Force evaluated and averaged the results of multiple studies that looked at health outcomes associated with beta-carotene and vitamin E supplementation. Beta-carotene is a phytonutrient, or plant chemical, with a red pigment orange; Both beta-carotene and vitamin E are found in many fruits and vegetables, including carrots, sweet potatoes, kale, spinach, Swiss chard, and avocados, to name a few.
The expert panel concluded that, with respect to prevention of cardiovascular disease or cancer, the harms of beta-carotene supplementation outweigh the benefits and that there is no net benefit of vitamin E supplementation for these purposes. Their recommendation applies to adults who are not pregnant and excludes those who are chronically ill, hospitalized or have a known nutritional deficiency.
Beta carotene and vitamin E are powerful antioxidants, substances that can prevent or delay cell damage. They are commonly taken as dietary supplements for their potential health and aging benefits, such as fighting age-related vision loss and inflammation associated with chronic disease. Vitamin E has also been shown to help support the immune system.
Our bodies require beta carotene and various nutrients for a variety of processes, such as cell growth, vision, immune function, reproduction, and normal organ formation and maintenance. But it is important to note that more than 95% of the US population receives adequate levels of vitamin A, vitamin E, and beta-carotene through the food they eat. Therefore, the average healthy adult likely does not need additional supplementation to support the processes listed above.
The task force did not focus on other potential benefits of vitamin supplements. He noted that “there may be other benefits of some supplements that were not covered in this review due to their focus on prevention of cardiovascular disease and cancer.”
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2. What risks did the working group point out?
Based on their review of the evidence, the expert panel concluded that beta-carotene supplementation probably increases the risk of incidence of lung cancer, particularly in those at high risk of lung cancer, such as people who smoke or have occupational exposure to asbestos. He also found a statistically significant increased risk of death from cardiovascular disease associated with beta-carotene supplementation.
In one of the clinical trials reviewed by the task force for its recommendation statement, people who smoked or had asbestos exposure in the workplace were at increased risk of lung cancer or death from heart disease at doses of 20 and 30 milligrams of beta-carotene daily. This dose is higher than the standard recommendation for beta-carotene supplementation, which varies from 6 to 15 milligrams per day.
3. Why were these supplements historically considered beneficial?
Antioxidants like beta-carotene and vitamin E can help fight inflammation and oxidative stress, two of the main contributors to the development of cancers and heart disease. Oxidative stress can trigger cell damage; when this happens, the cells can become cancerous.
With cancer and cardiovascular disease being the two leading causes of death in the US, it’s only natural that so many people choose to look to dietary supplements to potentially add a boost of prevention. Also, since only 1 in 10 Americans meets the federal recommendation For fruit and vegetable intake (1.5-2 cups of fruit and 2-3 cups of vegetables daily), people often turn to dietary supplements to make up for that deficiency.
There is strong evidence that a diet rich in fruits and vegetables is beneficial for general health and disease prevention. The researchers also suggest that this may be due in large part to its high antioxidant content. The dose of antioxidants received from eating a lot of foods rich in beta-carotene and vitamin E is not as high as the doses available in supplement form.
4. Should people be concerned about taking any kind of dietary supplement?
Rigorous testing is required before the Food and Drug Administration approves a drug. However, that is not the case for dietary supplements, which are regulated as a food, not a drug. Therefore, the FDA does not not have the authority approving the safety and efficacy of dietary supplements, or approving their labeling, before the supplements are sold to the public.
The size of the global market for dietary supplements was valued at US$151.9 billion in 2021. Based on data from the 2017-2018 National Health and Nutrition Examination Survey, an estimated 60% of American adults were taking some type of dietary supplement, including vitamins, minerals, multivitamins, botanicals and herbs, probiotics, powders nutritional and more.
Consumers must be careful when buying and consuming dietary supplements, as they may contain ingredients that could negatively interact with a prescription drug or medical condition. It’s also worth noting that products containing hidden drugs are also sometimes falsely marketed as “dietary supplements,” which can put consumers even more at risk.
This year, the FDA began working to strengthen the regulation of dietary supplements and has wrote a proposal modify your current policies.
