Can fruits and vegetables reduce cancer risk? truly! These 5 things are often eaten, and the average person can't think of it!

Reviewed by: Yilong Wu (Guangdong Provincial People's Hospital)

It is well known that smoking, including second-hand smoke, is the biggest and most definitive risk factor for lung cancer.

The World Health Organization (WHO) classifies tobacco, secondhand smoke, and e-cigarettes as Class I carcinogens[1].

Some foods, such as red meat (beef, etc.) and processed meat (cured, air-dried, fermented, smoked, etc., such as hot dogs, ham, sausages, beef jerky, and canned meat and meat ingredients), may raise the risk of colorectal cancer [2].

There are also foods that may reduce the risk of developing certain cancers. Last year, for example, a study confirmed that colorectal cancer patients who consumed at least 2 ounces of nuts per week had a 42 percent lower risk of cancer recurrence and a 57 percent lower risk of death [3].

So, are there any foods that reduce the risk of lung cancer or death?

The National Cancer Institute (NCI) reviewed existing high-quality studies on diet and lung cancer risk and found that due to the interference of smoking, it was not clear which foods reduced lung cancer incidence or mortality [4].

Image source: Stand Cool Helo

A team of experts at the World Cancer Fund (ECRF) reviewed a study published between January 2006 and December 2014 on the association of fruits and vegetables with lung cancer risk and found that for the overall population, vegetable and fruit intake exceeded 400 grams per day, the risk of lung cancer decreased by 27 percent [5].

However, after grouping the population by age, sex, whether they smoke, etc., the benefits of vegetables and fruits in reducing lung cancer risk only appeared in smokers, and they were nonlinear changes (not the more they ate, the more the risk was reduced), and for people who had smoked before but had quit smoking, 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 them reduce their lung cancer risk?

1. Cruciferous vegetables

Eleven studies in Europe, Asia, and North America showed that cruciferous vegetables (including cauliflower, radish, carrot, arugula, cabbage, kale, kale, watercress, wasabi, brussels sprouts, cabbage, turnips, mustard, etc.) reduced the risk of lung cancer in smokers, and after statistical analysis, it was estimated that for every 100 grams eaten per day, the risk of lung cancer decreased by 19%, and female smokers may have a more reduced risk of lung cancer than men [5].

2. Green leafy vegetables

Nine studies have shown that green leafy vegetables (including oil wheat, spinach, turnips, rape, longleaf lettuce, etc.) can reduce the risk of lung cancer in smokers, and after statistical analysis, it is estimated that every 50 grams of daily consumption reduces lung cancer risk by 9% [5].

3. Fruit

Fruit has been shown to reduce the risk of lung cancer in smokers in 23 studies, and after statistical analysis, it is estimated that the risk of lung cancer may be reduced by 18% when eating more than 200 grams to 300 grams per day. But no matter how much you eat, you won't lose more.[5]

Further analysis found that smokers may have an 8% lower risk of lung cancer when they eat more than 70 grams per day in citrus fruits (mandarin, citron, bergamot, orange, etc.).

But no matter how much you eat, you won't lower it more.[5]

In addition, the flavonoids contained in apples may reduce the risk of lung cancer in smokers, but flavonoids are mainly concentrated in the peel, and eating them after peeling will reduce the effect. Similarly, apple juice may not have had a role in reducing lung cancer.

4: Garlic and onion

A study from China suggested that people who ate garlic raw twice a week had a 44 percent lower risk of lung cancer among all populations [6].

According to the analysis of the study, this effect originates from the diallyl sulfide contained in garlic, which is greatly reduced by cooking, so it is recommended to eat it raw.

A U.S. study observed in Hawaii that residents who often ate garlic and onions had a lower risk of lung cancer [7].

5. Others

Previous studies have found that β-cryptoxanthin (carotenoids) may reduce the risk of lung cancer, but there have also been studies that have shown a decreased risk of lung cancer in people who eat foods containing β-cryptoxanthin , such as pumpkins , but not statistically significantly [5].

Previous studies have found that eating foods rich in vitamin E (whole grains or whole grains) may reduce the risk of lung cancer [8].

However, subsequent large studies suggest that no significant reduction in lung cancer incidence in the vitamin E group was observed in male smokers [9].

In addition, studies have found that people who are emaciated have a higher risk of lung cancer than people with a high body mass index [BMI = body weight (kg)/height (m)2] [10].

From this, it is important to ensure adequate nutrition. In addition, given that multiple foods have the potential to reduce the risk of lung cancer, it is also important to maintain a variety of diets.

It should be emphasized that these studies suggest that eating more fruits and vegetables may reduce the risk of lung cancer in smokers, but the decline is far less than the increase brought about by smoking.

Moreover, for people who have smoked before but have quit smoking, and who do not smoke, eating more fruits and vegetables did not bring about a decrease in the risk of lung cancer. Quitting smoking, reducing second-hand smoke, and reducing air pollution are still more effective ways to prevent lung cancer.

Co-review: Guangdong Provincial People's Hospital Guangdong Provincial Lung Cancer Research Institute Liao Riqiang Deputy Chief Physician Dr. Dong Song Dr. Zhang Tao

bibliography:

[1] John Heymach. et al. Clinical Cancer Advances 2018: Annual Report on Progress Against Cancer From the American Society of Clinical Oncology. J Clin Oncol[J/OL].published online before print,2018-01-30.

[2] IARC. Q&A on the carcinogenicity of the consumption of red meat and processed meat[J/OL]. IARC,https://www.cancer.org/cancer/cancer-causes/tobacco-and-cancer/is-any-type-of-smoking-safe.html#written_by,2013-11-13.

[3] Temidayo Fadelu, Donna Niedzwiecki, et al. Nut consumption and survival in stage III colon cancer patients[J]. Results from CALGB 89803 (Alliance). 2017 ASCO Annual Meeting. Abstract No:3517.

[4] National Cancer Institute.Lung Cancer Prevention[J/OL].https://www.cancer.gov/types/lung/hp/lung-prevention-pdq,2018-03-02.

[5] Vieira, A., et al. Fruits, Vegetables and Lung Cancer Risk: A Systematic Review and Meta-Analysis[J]. Annals of Oncology. 2016. 27(1):81-96.

[6] Zi-Yi Jin. et al. Raw Garlic Consumption as a Protective Fctor for Lung Cancer[J]. Cancer Prev Res. 2013. 6(7):711-718.

[7] Holly L. Nicastro. et al. Garlic and Onions: Their Prevention Properties[J]. Cancer Prev Res. 2015. 8(3):181-189.

[8] R Peto. et al. Can dietary beta-carotene materially reduce human cancer rates? [J]. Nature 1981;290:201-208.

[9] The Alpha-Tocopherol Beta Carotene Cancer Prevention Study Group.The Effect of Vitamine E and Beta Carotene on the Incidence of Lung Cancer and Other Cancers in Male Smokers[J]. N Engl J Med 1994;330(15):1029-1034.

[10] Olson JE, Yang P, Schmitz K, et al. Differential association of body mass index and fat distribution with three major histologic types of lung cancer:evidence from a cohort of older women[J]. Am J Epidemiol 156 (7): 606-15, 2002.

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