Mixed
Consuming five or more servings daily of a variety of vegetables and fruits reduces the risk of lung, oral, esophageal, stomach, and colon cancers, whereas high-dose beta-carotene supplementation in smokers increases lung cancer risk.
Aim for five or more servings of vegetables and fruits every day, spread across meals and snacks. Prioritize variety and whole forms (fresh, frozen, canned) over supplements. If you smoke, strictly avoid high-dose beta-carotene supplements as they may increase lung cancer risk.
Greater consumption of vegetables, fruits, or both together has been associated in the majority of epidemiological studies with a lower risk of lung, oral, esophageal, stomach, and colon cancer... Two of the clinical trials showed that smokers taking high-dose beta-carotene supplements developed lung cancer at higher rates than those taking a placebo
Why this rating
Based on consistent epidemiological studies and randomized trials showing harm from supplementation, though specific protective components are not fully isolated.
Source
American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention: Reducing the Risk of Cancer with Healthy Food Choices and Physical Activity
T. Byers et al. · CA A Cancer Journal for Clinicians · 2002
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