Beta carotene supplements may increase the risk of lung cancer in people with a history of smoking or asbestos exposure. However, experts generally consider it safe to consume beta carotene in foods.

Beta carotene is a red-orange pigment in plants, such as carrots. It is an antioxidant and a precursor to vitamin A, an essential nutrient for vision, skin health, and immune function.

Consuming beta carotene-rich foods is generally beneficial, providing necessary nutrients without the risks that high dose supplementation can have for people who have smoked.

Continue reading to learn more about the link between beta carotene and lung cancer.

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Beta carotene is a plant compound that belongs to the carotenoid family, a group of substances responsible for vibrant colors in many plant-based foods. It is a red-orange pigment that occurs in several fruits and vegetables, including carrots, spinach, kale, and sweet potatoes.

In the body, beta carotene functions as a precursor to vitamin A, also called provitamin A. The body converts beta carotene into this nutrient.

Beta carotene also acts as an antioxidant, helping safeguard cells from damage caused by harmful free radicals. By neutralizing free radicals, antioxidants help maintain overall health and may prevent certain health conditions.

There is a link between beta carotene supplements and lung cancer. However, there is no evidence of a link between lung cancer and beta carotene that occurs in the diet.

An extensive body of research going back several decades has explored the connection between beta carotene supplements and lung cancer:

  • The 1996 Alpha-Tocopherol, Beta Carotene Cancer Prevention Study reported an 18% increase in lung cancer incidence among male smokers taking beta carotene supplements.
  • Similarly, the 2004 Beta Carotene and Retinol Efficacy Trial looked at beta carotene and vitamin A supplement use in those at an increased risk of lung cancer due to smoking or asbestos exposure. It found the following among the group that took the supplements:

More recent research confirms these findings, noting that beta carotene supplementation increases the risk of lung cancer in those who smoke, regardless of the tar or nicotine content of the cigarettes in question.

People with a history of smoking or asbestos exposure should avoid beta carotene supplements.

However, it is important to note that while beta carotene supplements may not be safe for all, these products contain much higher amounts of the compound than occur naturally in fruits and vegetables.

For this reason, it is generally safe for people to eat plants containing beta carotene, even if the person has a history of smoking. In fact, some evidence suggests carotenoids in food may have a protective effect against lung cancer.

The findings of a 2017 study involving more than 2,500 participants suggest that, even among people who smoke heavily, there was a link between diets containing carotenoids and vitamin C and a lower risk of lung cancer.

It is unclear why carotenoids in food may be beneficial in lowering lung cancer risk while the higher doses in supplements can be harmful in people with a history of smoking or asbestos exposure.

A doctor can offer personalized advice about beta carotene consumption.

As part of a balanced diet, beta carotene offers several health benefits:

Anticancer properties

Beta carotene is a potent antioxidant that neutralizes free radicals, which are unstable molecules that can damage parts of cells, such as DNA, proteins, and lipids.

As a result of this damage, free radicals can disrupt normal cellular functions, potentially activating oncogenes (genes that promote uncontrolled cell growth) or deactivating tumor suppressor genes (genes that normally restrain cell division and promote DNA repair).

This imbalance can initiate carcinogenesis, the process by which normal cells transform into cancerous ones.

Consuming more fruits and vegetables rich in beta carotenoids has associations with a lower risk of various cancers, particularly cancers of the following areas:

Eye health

Beta carotene is essential for maintaining healthy vision and can help reduce the risk of certain eye conditions, such as age-related macular degeneration (AMD).

A 2017 study suggests that consuming a diet rich in carotenoids and vitamin C and can effectively reduce the risk of AMD in people who smoke.

Cognitive function

A 2023 review notes evidence that beta carotene from food has links to better cognitive function over the long-term.

However, it is important to note that beta carotene may not lead to this effect on its own. Instead, it may work alongside other micronutrients, such as vitamin E.

Beta carotene often occurs in yellow, orange, and red plants, as well as some leafy green vegetables. Sources include:

Beta carotene is a nutrient with numerous health benefits, especially for the eyes, skin, and immune system. The body can convert this nutrient into vitamin A. Beta carotene also functions as an antioxidant.

However, high dose beta carotene supplementation has links to an increased risk of lung cancer in people with previous exposure to smoke and asbestos. People in these groups should not take beta carotene supplements.

Instead, people can get beta carotene and other antioxidants from a diet rich in colorful plant-based foods. Some common sources of beta carotene include carrots, kale, and red or yellow bell peppers.