Nutrition and stomach cancer

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It is common for people with stomach cancer to have problems eating and digesting food. These problems are caused by:

  • the removal of all or part of the stomach
  • the removal of or damage to glands, specialized cells and nerves of the stomach that affect digestion of food
  • the removal of or damage to the rings of muscle that control food coming into the stomach (called the lower esophageal or cardiac sphincter) and leaving the stomach (called the pyloric sphincter)
  • side effects of chemotherapy or other treatments
  • a loss of appetite caused by the cancer itself
  • the stomach not emptying properly, which makes you feel full for longer than normal

The healthcare team, including a registered dietitian, can help you maintain nutrition during treatment and deal with any side effects and changes to your appetite. A dietitian is a key member of the healthcare team who can provide counselling about proper nutrition that's right for you.

Nutrition problems may include the following.

Weight loss

Weight loss is a very common problem for people with stomach cancer. A stomach tumour can cause blockages, so that food can't pass normally from the esophagus into the stomach or from the stomach into the intestine. This can make it hard to eat. When cancer is advanced, the body's ability to use the energy from food is changed. As a result, energy is burned at a faster rate. This increased energy use combined with a lower nutritional intake results in weight loss.

There are other factors that can lead to weight loss in people with stomach cancer:

  • People with stomach cancer often have a loss of appetite and may not feel like eating.
  • After stomach cancer surgery, you may not be able to eat large meals and may feel full after eating small amounts of food. This is usually related to how much of the stomach is removed.
  • The remaining stomach or small intestine may not digest food properly or absorb fats and nutrients from food. This depends on the type of surgery and how much of the stomach is removed.
  • Dumping syndrome may make it harder to maintain your weight. Dumping syndrome is a condition that causes food or liquid to move through the stomach and small intestine too quickly. Dumping syndrome may occur when part or all of the stomach is removed.

It is important to maintain your weight even if your appetite has changed. Proper nutrition helps the body fight disease and cope with the effects of stomach cancer treatment.

If weight loss is a problem, the following tips may be helpful:

  • Don't skip meals. Try to eat regularly, even if it is only a few bites.
  • Make every mouthful count by choosing foods and drinks that are high in protein and calories. Add whole milk or cream to cooked cereals or soups, use sauces and gravies on meats and vegetables or add extra butter or margarine to potatoes.
  • When you don't want to or can't eat solid foods, drink high-calorie, high-protein beverages (like shakes, smoothies or commercial liquid supplements) or eat semi-solid foods (like pudding or yogurt). Also take high-calorie, high-protein drinks between meals in small amounts.
  • Keep a variety of nutritious foods that are high in protein and calories, as well as quick and easy snacks, on hand so they are ready to eat when you are. Examples include milk or milkshakes, instant breakfast preparations, ice cream, cheese and crackers, muffins, peanut butter, eggs, nuts, yogurt and puddings.

If weight loss becomes severe, the healthcare team may suggest using a feeding tube. A feeding tube is a thin, flexible tube that is placed into the stomach or intestine. Once the tube is in place, liquid nutritional supplements can be given through it (called enteral feeding). Feeding tubes can help people get their nutritional needs when they find it too hard to eat or drink, especially if they have lost a lot of weight. Learn more about feeding tubes.

Feeling full after eating and drinking

You may feel full after eating even small amounts of food. This can happen whether or not you have had surgery. Surgery for stomach cancer reduces the size of the stomach and can cause scarring of the stomach wall. Surgery may also damage the vagus nerve, which relaxes the stomach wall when food enters the stomach. This will improve as the remaining part of the stomach stretches or as the body adjusts to the changes in digestion. Even without surgery, your stomach may empty much more slowly, keeping you feeling full for longer periods of time.

If feeling full after eating small amounts is a problem, the following tips may be helpful:

  • Try to eat smaller meals or snacks about 6 times a day. This is usually easier than trying to eat 2 to 3 large meals a day.
  • Avoid drinking fluids with meals, especially carbonated (fizzy) drinks. These fluids can fill the stomach quickly. Drink high-calorie or high-protein fluids between meals.
  • Limit the amount of high-fibre foods, such as whole grain breads and cereals, because they tend to make you feel full sooner than other foods.

Getting enough vitamins and minerals

People who have stomach cancer often have problems getting enough vitamins and minerals. This may be because of surgery that removes all or part of the stomach or a large tumour that makes it hard to eat. Your healthcare team can suggest ways to help you get the right amount of vitamins and minerals.

Vitamin B12

Vitamin B12 is important in making red blood cells as well as keeping the nervous and digestive systems healthy. Low vitamin B12 levels occur after all or part of the stomach is removed and can lead to anemia. Cells in the lining of the stomach (called parietal cells) make a substance called intrinsic factor, which helps the body absorb vitamin B12. Anemia caused by low vitamin B12 levels is called pernicious anemia. People who have had surgery for stomach cancer are often given vitamin B12 (by injection or oral supplement) to help prevent anemia.

Find out more about anemia.


Iron is a mineral that is important in making red blood cells. The acid in the stomach helps the body absorb iron. If you have surgery to remove your stomach (called a gastrectomy), your iron levels may go down. Iron levels may also drop if part of the duodenum, where most of the iron is absorbed, is removed during a gastrectomy.

Low iron levels can lead to anemia. If you've had a gastrectomy, you may be given an iron supplement. Your dietitian may also advise you to eat more foods with lots of iron, such as green leafy vegetables, red meats and fish.


Calcium is an important mineral for building strong bones and teeth. When the duodenum is removed by surgery, the body absorbs less calcium. Calcium absorption is also lowered by dumping syndrome because the stomach contents are emptied into the intestines too quickly. A person with stomach cancer may not get enough calcium from their food. Low calcium levels may lead to osteoporosis. The healthcare team may suggest that you take a calcium supplement to treat low levels of calcium.


Folate is important for making red blood cells. Low folate levels may occur because people with stomach cancer may have problems eating a healthy diet. Changes in the structure of the stomach and intestines following surgery may change the body's absorption and digestion of folate. Not getting enough folate can lead to anemia. Your healthcare team may suggest that you take a folic acid supplement.

Other vitamin and mineral supplements

You may also need to take other vitamin and mineral supplements if your stomach was removed. Eating a healthy diet often doesn't provide enough vitamins or minerals if the body can't absorb them properly from regular foods. The healthcare team may recommend a multivitamin that contains many important vitamins and minerals.

The healthcare team may also suggest you take commercial nutrition supplements. Commercial nutrition supplements are a good source of calories and nutrients and come in a variety of flavours and forms, including a ready-to-use beverage (similar to a milkshake), a powder, a pudding and a bar. They are sold in pharmacies and grocery stores, and you don't need a doctor's prescription to buy them. Some provincial and private healthcare insurance plans may cover the cost under certain conditions.

Find out more about eating well during and after treatment.

Expert review and references

  • American Cancer Society . After Stomach Cancer Treatment . 2017 :
  • American Society of Clinical Oncology (ASCO) . Cancer.Net: Stomach Cancer. 2020:
  • Memorial Sloan Kettering Cancer Center. Eating After Your Gastrectomy. New York, NY: 2019.
  • National Comprehensive Cancer Network . NCCN Clinical Practice Guidelines in Oncology: Gastric Cancer (Version 1.2019).

Medical disclaimer

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