Nutrients, Food, and Stomach Cancer Risk

Review of Cancer Causes Control. 2004;15(1):67-72.

A study in the journal Cancer Causes and Control looked at the connection between nutrition and stomach cancer. Researchers studied a group of nutrients found in fruit and vegetables that are called flavonoids. This study found that eating plenty of flavonoids, as well as eating a lot of vegetables, appears to significantly decrease the risk of stomach cancer. In particular, a group of flavonoids called flavanones appears to best decrease the risk of stomach cancer. We provide PRACTICAL information on what these findings mean. We discuss which foods are the best sources of flavanones and how you can get more of these foods into your diet. We provide ideas for how this information can be incorporated into a healthy dietary plan. This type of information will allow people to take concrete and practical steps that may decrease their risk of stomach cancer.

Note: Numbers appearing at the end of sentences indicate research references. References are listed at the end of each article.

Background

Some things that increase the risk of stomach cancer include infection with a type of bacteria called helicobacter pylori (H. pylori) and use of tobacco and alcohol (smoking and drinking) (1-4). However, even for people with these risk factors (H. pylori, smoking and drinking), certain types of diet, such as eating a lot of fruits and vegetables, appear to greatly decrease the risk of stomach cancer (2,5-23). This has led to interest in determining which specific foods and nutrients might protect best against stomach cancer. A study published in the journal Cancer Causes and Control looked at a specific group of nutrients, called flavonoids, and risk of stomach cancer (27). Factors such as age, genetics and past use of tobacco and alcohol cannot be changed, but diet and nutrition can! It is hoped that this type of research will help us gain more information about the connection between what we eat and risk of stomach cancer.

What The Researchers Studied

For this study (24), 110 Greek men and women with stomach cancer and 100 Greek men and women without stomach cancer were asked about their diet. Researchers looked at a type of stomach cancer called adenocarcinoma. Information on other important health factors including gender, age, height and weight, place of birth, level of education, and use of tobacco and alcohol (smoking and drinking) was collected and accounted for in this study. Researchers used this information to examine whether eating certain foods or eating more of a group of nutrients called flavonoids, which are found in fruit and vegetables, was related to having a history of stomach cancer. 

What The Study Found

First, after adjusting for many other dietary factors, the researchers found that eating more vegetables overall decreased the likelihood of being diagnosed with stomach cancer. To arrive at this conclusion, the researchers compared people eating various levels of vegetables, relative to each other. For this reason, exact amounts of vegetables were not discussed in the research paper. However, the researchers did show a direct connection between eating more vegetables and lower risk. In other words, the more vegetables in the diet, the lower the likelihood of being diagnosed with stomach cancer.

Second, after adjusting for many other dietary factors, the researchers found that eating more of a certain type of nutrient called flavanones lowered the likelihood of being diagnosed with stomach cancer. The researchers studied six different types of flavonoids, which are nutrients that are found in fruit and vegetables. Only flavanones appeared to decrease the risk of stomach cancer.

Again, to arrive at this conclusion, the researchers compared people eating various levels of flavanones, relative to each other. For this reason, exact amounts of flavanones are not available from the information presented in the paper. However, the researchers did show a direct connection between eating more flavanones and lower risk. In other words, the more flavanones in the diet, the lower the likelihood of being diagnosed with stomach cancer.

What do these results mean?

If we assume that the people in this study are like most people, then this study suggests that eating more vegetables overall and eating more of a group of nutrients called flavanones may decrease risk of stomach cancer. It is important to note that the researchers were studying flavanones from FOOD sources, not dietary supplement pills.

However, before we decide what these results mean, it is important to consider some of the limitations and weaknesses of this type of study.

The results of this study may or may not apply to people living in countries other than Greece. There are MANY differences in diet and other health factors between Greek and non-Greek people. We don't know if researchers would find the same results if they were studying other groups of people.

Also, this type of research cannot prove cause and effect. The study only tells us that there is an association between eating more vegetables and flavanones and stomach cancer risk. It is important to remember that an association is not causation (cause and effect). There are many other factors that could account for or explain the results of the study.

As well, the people in this study were asked about their diet after they were diagnosed with stomach cancer. This can create problems with the research because sometimes people remember their diet differently if they already have a disease. This is called recall bias and it can be a problem with this type of research.

On a positive note, the results of this study agree with other research telling us that vegetables and fruit and the nutrients that are found in these foods may reduce risk of stomach cancer (2,7-9,12,15,17-19). This means that even though this study (24) was conducted in Greece, the results probably apply to other people as well.

In summary, despite some weaknesses of the study reviewed (24), it fits well with what we know about diet and stomach cancer risk. It adds another useful piece of information to the puzzle.  

More importantly, there are NO downsides to improving diet and eating healthy!

Tips For Eating More Vegetables And Flavanones To Improve Diet

Use the following tips to help yourself eat more vegetables and more foods that contain a group of nutrients called flavanones.

Vegetables

• Rely on frozen produce during the off-season. Frozen vegetables are as healthy as fresh. In the off-season, frozen vegetables actually can pack more vitamins, minerals, and phytochemicals than fresh.
• Stuff your favorite omelet with low-fat shredded cheese, tomatoes, and frozen spinach (cook & drain spinach first).Keep little 6 oz cans of low-sodium vegetable juice handy for a quick serving of vegetables.
• Snack on baby carrots and hummus.
• For a tasty salad, steam several cups of frozen or fresh vegetables (cauliflower, carrots, broccoli, Brussels sprouts), until tender and crisp; Add 1/4 to 1/2 cup of salad (Italian) dressing; Mix well and refrigerate until chilled. 
• Improve the nutrition value of your family's favorite main dish casserole by adding one cup of frozen mixed vegetables; Try to look for the veggie blends that include cauliflower, broccoli, and carrots.
• Stuff your favorite potato with phytochemical rich toppings such as stewed tomatoes, green and red peppers, onions, broccoli, and low-fat cheese; Try a sweet potato instead of a white potato and you get even more nutrition value.
• Try adding a stir fry to your weekly menu: 

Spicy Broccoli, Cauliflower, and Tofu Stir Fry

• Tasty Tempeh Stir Fry

Flavanones

Flavanones are a group of nutrients that are found in abundance in citrus fruit (25). To get more flavanones into your diet, you need to eat more citrus!

• A small glass of orange juice is loaded with flavanones. Have 6 ounces of 100% orange juice with breakfast.
• Enjoy citrus fruit as a snack. Take an orange to work and eat this instead of your usual apple or banana.
• Squeeze the juice of a whole lemon or lime into your tea or water. This is an easy way to add flavanones to your diet.
• Try different types of citrus for variety. For example
  • Try Kumquats - these are small citrus fruit that can be eaten peel and all. Cut them in half and put them on your next salad.
  • Try clementines - this fruit is a cross between an orange and a mandarin tangerine. They are easy to peel and have very few seeds, making them perfect for snacking. 
  • Try Ugli Fruit - these thick peeled fruit are sometimes called the more politically correct "Unique Fruit".

NOTE: If you are in cancer treatment, these diet changes may not be right for you.

References

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2. Lee SA, Kang D, Shim KN, Choe JW, Hong WS, Choi H. Effect of diet and Helicobacter pylori infection to the risk of early gastric cancer. J Epidemiol. 2003;13(3):162-68.

3. Xia HH, Wong BC, Lam SK. Chemoprevention of gastric cancer: current status. Chin Med J (Engl). 2003;116(1):5-10.

4. Chao A, Thun MJ, Henley SJ, Jacobs EJ, McCullough ML, Calle EE. Cigarette smoking, use of other tobacco products and stomach cancer mortality in US adults: The Cancer Prevention Study II. Int J Cancer. 2002;101(4):380-89.

5. Ito LS, Inoue M, Tajima K, Yamamura Y, Kodera Y, Hirose K, Takezaki T, Hamajima N, Kuroishi T, Tominaga S. Dietary factors and the risk of gastric cancer among Japanese women: a comparison between the differentiated and non-differentiated subtypes. Ann Epidemiol. 2003;13(1):24-31.

6. Sauvaget C, Nagano J, Hayashi M, Spencer E, Shimizu Y, Allen N. Vegetables and fruit intake and cancer mortality in the Hiroshima/Nagasaki Life Span Study. Br J Cancer. 2003;88(5):689-94.

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24. Lagiou P, Samoli E, Lagiou A, Peterson J, Tzonou A, Dwyer J, Trichopoulos D. Flavonoids, vitamin C and adenocarcinoma of the stomach. Cancer Causes Control. 2004;15(1):67-72.

25. USDA Database for the Flav0noid Content of Selected Foods. Available at: http://www.nal.usda.gov/fnic/foodcomp/Data/Flav/flav.pdf. Accessed February 2, 2005.

Publish Date: 02/2005