It is well known that smoking, including secondhand smoke, is the largest and most definitive risk factor for lung cancer. The World Health Organization (WHO) classifies tobacco, secondhand smoke, and e-cigarettes as class I carcinogens. Some foods are associated with the development of certain cancers, such as red meat (beef, etc.) and processed meats (cured, dried, fermented and smoked meats, such as hot dogs, ham, sausage, beef jerky, and canned meats and meat ingredients), which may increase the risk of colorectal cancer. There are also some foods that may reduce the risk of certain cancers. For example, a study last year confirmed that colorectal cancer patients who ate at least 2 ounces of nuts per week had a 42% lower risk of cancer recurrence and a 57% lower risk of death.
So are there any foods that can reduce the risk of developing or dying from lung cancer?
There are no foods that can reduce the risk of lung cancer.
The National Cancer Institute (NCI) evaluated the higher-quality studies available on diet and lung cancer risk and found that no specific foods are known to reduce lung cancer incidence or death because of the confounding factor of smoking.
A group of experts from the World Cancer Foundation (ECRF) evaluated studies published between January 2006 and December 2014 on the association between fruits and vegetables and lung cancer risk and found that for the total population, lung cancer risk was reduced by 27% when vegetables and fruits were consumed at more than 400 grams per day. However, when the population was grouped by age, sex, and whether or not they smoked, the benefit of vegetables and fruits in reducing lung cancer risk was only seen in those who smoked and was nonlinear (not a greater risk reduction with more food), and for those who had previously smoked but had quit, or had never smoked, vegetables and fruits did not significantly reduce the risk of lung cancer.
So, for smokers, which fruits and vegetables can help reduce their lung cancer risk?
Cruciferous vegetables:
Eleven studies in Europe, Asia, and North America have shown that cruciferous vegetables (including cauliflower, radish, carrot, arugula, bok choy, kale, collard greens, watercress, wasabi, Brussels sprouts, cabbage, turnip greens, and mustard) can reduce lung cancer risk in smokers, with a statistically significant 19% reduction in lung cancer risk for every 100 grams eaten per day, and in women smokers The risk reduction may be greater for women than for men.
Green leafy vegetables:
9 studies have shown that green leafy vegetables (including oleander, spinach, turnips, rape, long-leaf lettuce, etc.) can reduce the risk of lung cancer in smokers, and after statistical analysis, every 50 grams consumed daily is predicted to reduce the risk of lung cancer by 9%.
Fruits:
23 studies have shown that fruit can reduce the risk of lung cancer in smokers, and after statistical analysis, it is predicted that the risk of lung cancer may be reduced by 18% for every 200 grams to 300 grams eaten per day. But eating more doesn’t lower it any more.
Further analysis found that citrus fruits (mandarins, citron fruits, bergamot, oranges, grapefruit, tangerines, etc.) were predicted to reduce lung cancer risk by 8% in smokers who ate more than 70 grams per day. But eating more won’t reduce it by more.
In addition, apples contain flavonoids that may reduce the risk of lung cancer in smokers, but the flavonoids are concentrated in the peel, and peeling them before eating reduces their effect. By the same token, apple juice may not have the effect of reducing the occurrence of lung cancer.
Garlic, onion:
A study from China suggests that people who ate raw garlic twice a week had a 44% lower risk of lung cancer in all populations. The study analyzed that this effect stems from the fact that garlic contains diallyl sulfide, which is greatly reduced by cooking and is therefore recommended to be eaten raw. And a U.S. study among Hawaii residents observed a lower risk of lung cancer among those who ate garlic and onions regularly.
Other:
Previous studies have found that beta-cryptoxanthin (carotenoids) may reduce the risk of lung cancer, but there are also studies that have shown a reduced risk of lung cancer in people who smoke who eat foods containing beta-cryptoxanthin, such as pumpkin, but not in a statistically significant way.
Previous studies have found that eating foods rich in vitamin E (whole grains or whole cereals) may reduce the risk of lung cancer. However, the results of subsequent large studies suggest that in the male smoking population, no significant reduction in lung cancer incidence was observed in the vitamin E group.
In addition, studies have found that people who are lean have a higher risk of lung cancer relative to those with a high body mass index [BMI=weight (kg)/height (m)]. This inferred that it is important to ensure adequate nutrition. In addition, it is important to maintain a varied diet, considering that a variety of foods has the potential to reduce lung cancer risk.
It is important to emphasize that all of these studies suggest that eating more fruits and vegetables may reduce the risk of lung cancer in smokers, but the decrease is much less than the increase associated with smoking. In addition, for former smokers who have quit, and for non-smokers, eating more fruits and vegetables did not result in a reduction in lung cancer risk. The most effective way to prevent lung cancer is to quit smoking, reduce secondhand smoke, and reduce air pollution.
Co-reviewed by Dr. Dong Song Dr. Zhang Tao, Guangdong Provincial People’s Hospital, Guangdong Provincial Lung Cancer Institute, Associate Chief Physician Liao Riqiang