Inhale, exhale, inhale, exhale, repeat. As we instinctively take fresh air in and push waste gases out, it’s easy to forget about the harmonious inner workings of the system that helps us to breathe. Our lungs are a vital part of this setup known as the respiratory system. In 2020, lung cancer was responsible for over 2.2 million new cancer cases worldwide. That same year, lung cancer topped the list of most common causes of cancer death once again, with 1.8 million lives lost (1). These staggering statistics are more than just numbers. They represent real people who've had their lives directly changed by lung cancer and shed light on the importance of finding safe and effective strategies for preventing lung cancer.
Diet and nutrition are factors long associated with both increasing and decreasing the risk of developing cancer. Zeroing in on lung cancer, it appears that consuming red and processed meats may increase lung cancer risk, while a diet rich in soy, fish, fruits, and vegetables may help lower it (2;3). Some also believe the consumption of vitamins and minerals through dietary supplements can help reduce the risk of developing lung cancer. But does the science support healthy populations taking supplements for this purpose? One systematic review is likely to have you rethinking supplements as a lung cancer prevention strategy (2).
What the research tells us
The review looked at the use of various supplements, including vitamin A, vitamin C, vitamin E, calcium, vitamin D plus calcium, selenium, and the combination of vitamins A, C, E, selenium, and zinc in healthy populations. Overall, the results were disappointing and, in some cases, concerning.
The review found that none of the individual supplements or supplement combinations investigated reduced the risk of lung cancer incidence or lung cancer death compared to placebo. What’s more, some supplements actually increased the risk of certain outcomes and produced minor to serious side effects. For instance, vitamin A increased the risk of lung cancer incidence and death, as well as death from all causes, in people who smoke and in people exposed to asbestos. Minor side effects with the use of vitamin A included gastrointestinal symptoms and skin yellowing. Vitamin C also increased the risk of lung cancer incidence, but this time in women. Vitamin E increased the risk of experiencing hemorrhagic strokes, also known as bleeding into the brain. Lastly, selenium increased the risk of hair loss and skin irritation. The findings for vitamin A, vitamin E, selenium, and the combination of vitamins A, C, E, selenium, and zinc were all based on high certainty evidence, meaning we can be very confident in these results. Our confidence in other results—such as those for calcium and vitamin D plus calcium—is lower, so future studies may show different results.
Ultimately, research evidence does not currently support the use of supplements for lung cancer prevention in healthy people (2). It’s important to remember that some people may be prescribed supplements due to certain vitamin deficiencies or medical conditions. Be sure to consult with your health care team prior to starting or stopping any supplements.
Evidence-backed lung cancer prevention strategies
- Smoking Cessation: Smoking is the leading cause of lung cancer. So, if you don’t smoke, then don’t start, and if you do smoke, quit. Luckily, there are plenty of strategies that can help on your journey to successfully quitting: 1) consider nicotine replacement therapy, 2) lean on your peers for support through group therapy (available in-person or online), and seek telephone support from a counsellor via helplines/quitlines/hotlines or different health care settings (6-10).
- Diet and Nutrition: Consume a healthy diet abundant in fruits and vegetables (2-5).
