For years, some doctors have insisted that taking vitamins is a waste of effort, not to mention money. They believe that simply eating a well-balanced diet should provide all the nutrients any of us needs. (Never mind that many people find it difficult to follow a balanced diet, for a variety of reasons.) Other healthcare practitioners are sure that vitamin supplements are helpful. Both the VITAL and the COSMOS trials provided good scientific evidence to support that view. Very few experts, however, have considered which vitamin formulation might be best. One reader has been working hard to figure this out.
Should Ex-Smoker Avoid Beta Carotene?
Q. I want to buy a multi-vitamin for my husband, an ex-smoker. I am trying to find out if beta carotene would be safe for him. Studies show it increases lung cancer in smokers and ex-smokers.
Some websites say smokers, ex-smokers and people exposed to asbestos should never take beta carotene. That was the conclusion from the VITAL trial. Other websites recommend mixed carotenoids. I am confused and not sure what is safe and how much of these supplements, if any, he should take. I am looking for a vitamin formulation without vitamin A but have not found any.
Beta Carotene Is Risky for Smokers:
A. Way back in the 20th century, a large randomized clinical trial tested vitamin E, beta carotene, the combination or double placebo in Finnish men who smoked (New England Journal of Medicine, April 14, 1994). The evidence was discouraging. Instead of reducing their chance of lung cancer, men who took beta carotene supplements were more likely to develop lung cancer during the follow-up years. Because beta carotene is a precursor to vitamin A, these results have been generalized to include vitamin A as well.
This finding surprised the investigators. After all, previous epidemiological studies had shown that beta carotene in healthy non-smokers appears to protect against lung cancer. In addition, smokers are at much higher risk for lung cancer. More recent research confirms that smokers with higher vitamin A intakes run a greater risk of lung cancer (Cancers, Oct. 21, 2022). This study did not show that beta carotene is dangerous for former smokers, but we understand why you would not want to put your husband in possible danger.
Single-Ingredient Vitamin Formulation May Be Worst:
The VITAL trial you mention concluded that the problem lies with isolated supplements:
“Long-term use of individual β-carotene, retinol, and lutein supplements should not be recommended for lung cancer prevention, particularly among smokers” (American Journal of Epidemiology, April 1, 2009).
A careful meta-analysis of 12 randomized clinical trials found that vitamin A in any form did not affect the risk of lung cancer, except for smokers or asbestos workers (Cochrane Database of Systematic Reviews, March 4, 2020). In such high-risk individuals, vitamin A or beta carotene increases the risk of lung cancer. The analysis did not identify risks for former smokers.
In light of these findings, you may want to search online for a multivitamin without vitamin A for your husband. Unfortunately, that may be challenging. When we looked, we found only a few.