Changes in Gastric Cancer Risk with Increased/Decreased Consumption of Fruits & Vegetables

Gastric Cancer has Lesser than a 5-Year Survival Rate

Garlic & Onions are Believed to be Great Saviors Against Cancer

Fruits and vegetables are like the foundation of a building. A shaky foundation can never hold a strong building likewise, absence of fruits and vegetables from our meals can never fulfill nutrient requirements and health outcomes. Many hate veggies, some like only a few veggies while a few others love to eat fruits only in the form of smoothies or juices that contain ample sugar. With such likes and dislikes, eating five portions of fruits and vegetables daily becomes a nightmare. Still, their benefits on health and positive effects on our body cannot be sidelined.
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Gastric cancer remains as the second-most cause of cancer death worldwide and the fourth most common type of cancer diagnosed in people worldwide. It is a disease where malignant cells form in the lining of the stomach. Common risk factors include stomach diseases such as gastric polyps, Epstein-Barr virus, chronic gastritis, etc., diet and age of the person. Men are at an increased risk and old age too puts one at a high-risk category. Stomach is where the food gets digested and what you eat plays a prominent role in assessing your risk of gastric cancer. Salty, smoked foods, eating those foods that have not been prepared properly or stored well and a diet lacking in fruits and vegetables are common risk factors of gastric cancer.

While diet is quoted as a common risk factor and we have evidences supporting it from case-controlled studies, those from cohort studies don’t bring us to any decisive conclusions.

EPIC Study: Europe
EPIC is a broad-scale study that was carried out in 23 centers in 10 different European countries on more than 5,00,000 subjects of which 70% were women aged between 35 and 70 years. The food habits of these volunteers during the last 12 months were noted down in the form of questionnaires, personal interviews or online forms in different countries. There were questions related to smoking, alcohol intake, education, exercise and reproductive history as well.

Vegetables and fruits intake were recorded in grams daily. A secondary dietary measurement was taken from around 8% of the study participants using a 24-hour dietary recall to note down consumption of total fruits, total vegetables and total fruits and vegetables consumption. After excluding participants due to various reasons such as previous prevalence of cancer, insufficient information and so on the final number consisted of 477,312 participants, in which 683 (almost 60% of them were men)  of them suffered from stomach adenocarcinomas (gastric cancer or GC), who were followed for around 11 years. Results were observed for all stomach cancer as well as cardia, noncardia, intestinal and diffuse subtypes. Analysis showed that:
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1. 201 (30%) were located in the cardia, 323 (47.3%) were located in the distal part of the stomach and for 159 others localization was unknown.
2. For both sexes, mean intake of total veggies in the upper quintile was more than twofold higher than in the lowest. For fruits, it was 6-folds higher in men and 3-folds higher in women
3. Individuals who consumed maximum portions of fruits and veggies were usually mostly non-smokers, had high education levels, more physical activity, increased energy intake and increased consumption of red meat but decreased consumption of processed meat
4. An inverse association was observed for total fruits and vegetables for the highest vs lowest quintile intake; an inverse association between citrus fruit intake and cardia cancer and also between diffuse type and total fresh fruit intake.
5. There was no strong evidence linking a particular subgroup of vegetables and GC risk.
6. There was significant link between total fruit and vegetable intake and total vegetable and GC risk.
7. There was an inverse association between citrus fruits intake and cardia GC risk, a weak association between intestinal GC risk and leafy vegetables, garlic and onion consumption and inverse association between fruits and vegetables consumption and overall GC risk.
   
   

GC doesn’t have even a 5-year survival rate in most cases and hence, reducing the occurrence of GC by controlling risk factors is the best way to handle the problem.

Shanghai Men’s & Women’s Health Studies
Gastric cancer exists as the second-most common type of cancer next to lung cancer in China and also is the third cause of death due to cancer. There are multiple studies supporting the intake of fruits and vegetables in reducing the risk of cancer-as much as 40% when consuming fruits and 30% for vegetables for the highest versus lowest categories of intake. Whereas, there has also been a meta-analysis showing that the link between reduced cancer risk and produce consumption is weaker-only 18% for high fruits intake and 12% for veggie intake. Two population-based studies, the Shanghai Women’s Health Study (SWHS) & Men’s Health (SMHS) study was conducted to cross check this result and come to decisive conclusions.

The SWHS included an 81-item food questionnaire and the SMHS included a 77-item food questionnaire with the major difference between them being: the SWHS included sweet potatoes, combines fresh soybeans, fresh peas and fresh broad beans into a single category while the SMHS collects information on each of these individually. SMHS includes additional items such as chrysanthemum, shepherd’s purse, clover and amaranth, pea shoots and pig’s ham hock. Participants were questioned on the frequency of these foods consumed and the quantity consumed every time they eat a fruit or vegetable. They were also asked about how many months of the year that the volunteers consumed a fruit or vegetable. Both the studies excluded those individuals suffering from cancer, gastrectomy and a haphazard total energy intake <500 kcal or >4000 kcal.

All fruits, citrus and non-citrus excluding watermelon, all vegetables, cruciferous, green leafy veggies, alliums, legumes and others, and micronutrients such as vitamin A, vitamin C and E, carotene, retinol, selenium and folic acid were included to create quartiles of intake. Results tabulated conveyed the following:
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1. Fruit intake was not associated with distal gastric cancer risk for women but in men, an increase in intake of all fruits (with the exception of watermelon) led to a decreased risk of distal gastric cancer. Apples showed a significant association with decreased risk compared to other fruits such as pears, tangerines, bananas, grapefruit, peaches and others
2. Vegetable intake (including all the varieties mentioned above) was not associated with a lower risk of GC in both men and women. In women belonging to the second quartile of consumption (boy choy and spinach) there was a 39% reduction in risk of GC but increased consumption did not alleviate the risk any further
3. No micronutrient was associated with GC risk in either men or women
4. Risk of GC was lower when consumption of fruits was higher in men who smoked (almost 60% lower) while in non-smokers, there was a smaller reduced risk from high intake of fruits
5. Increased intake of fruits (Excluding watermelon) was associated with a decreased risk of GC in men (around 46%) in the fourth quartile compared to men in the first quartile.
   
   

The study showed a clear association between fruits intake and reduced GC risk in men-the gender which consumes lower portions comparatively. This study hence shows that it’s the high-risk group that fruit intake confers a protective effect against distal cancer. In the SWHS, a vegetable-rich diet was not associated with a woman’s mortality but a fruit-rich diet was found to be protective. The study clearly proves that fruit intake is inversely associated with distal gastric cancer risk in men, especially in those who have ever smoked.
A meta-analysis of 17 studies showed that consumption of fruits and not vegetables reduced the risk of gastric cancer. There was an inverse associated between fruits consumption and GC risk but no significant difference observed in the case of vegetables.

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Micronutrients Protect Our Body Against Health Issues

​Another study focused on the antioxidants present in fruits and vegetables that decrease the risk of GC in individuals. The protective effect of produce has been mainly due to the presence of antioxidant effect of the vitamin contents such as tocopherols and vitamin C. But the number of studies analyzing this effect (antioxidants and risk of gastric cardia cancer (GCC) and gastric noncardia cancer (GNCC)) is extremely limited. One such study focused on the intake of fruits and vegetables and the effect of antioxidants on the risk of GCC and GNCC.
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Increased intake of fruits did not alter risk of GCC but did decrease the risk of GNCC. Intake of vitamin C was not associated with a risk of GCC but moderate to high intake of vitamin C was linked to a 40% reduced risk of GNCC.  Retinol intake was linked to a dose-dependent protective association with GCC but did not prove anything for GNCC. γ-Tocopherol was associated with an elevated risk of GCC (2-fold increased risk) but a decreased risk of GNCC. So, increased intake of retinol proved to be protective against GCC whereas increased intake of fruits, vitamin C, tocopherols and lycopene was protective against GNCC.

References
Fruit & Vegetable Consumption & the Risk of Gastric Adenocarcinoma: https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.27565
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Fruits & Vegetables Consumption & Risk of Distal Gastric Cancer in the Shanghai’s Women’s & Men’s Health Studies: https://academic.oup.com/aje/article/172/4/397/85175

Consumption of Fruits but Not Vegetables Reduce the Risk of Gastric Cancer: https://www.ejcancer.com/article/S0959-8049(14)00150-6/fulltext
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Fruits, Vegetables & Antioxidants & Risk of Gastric Cancer among Male Smokers: http://cebp.aacrjournals.org/content/14/9/2087
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Gastric Cancer Treatment: https://www.cancer.gov/types/stomach/patient/stomach-treatment-pdq

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