Cancer: How a change in diet can break the vicious circle

Over 50% of cancer patients are malnourished. Attending to the diet of cancer patients early in the treatment process is key to improving their quality of life and prognosis.

Nutrition issues are part of a vicious circle in cancer 

In addition to the cachexia (weakness and wasting) associated with severe illness, the side effects of cancer treatment such as loss of taste, difficulty chewing and swallowing, nausea and diarrhoea can adversely affect the nutritional status of patients. A deterioration in nutritional status lowers tolerance to and efficiency of treatments, which leads to a downturn in quality of life and has a negative effect on prognosis.

What is the recommended diet for cancer patients?

In 2017 the European Society for Clinical Nutrition and Metabolism published guidelines on nutrition in cancer patients. The report emphasises that no evidence has been found to support the notion that certain nutrients may “feed the tumour”. Fasting before, during or after chemotherapy is not recommended for malnourished patients, nor are strict diets and rapid intervention in the form of nutritional advice is required wherever a low or moderate malnourishment is detected.

Energy requirements are the same for cancer patients as for healthy individuals, i.e. 30–35 kcal per kg of bodyweight per day. Oral nutritional supplements are only necessary in the most severe cases, with a preference for animal rather than plant-based protein and whey rather than casein, especially for the elderly. Protein assimilation and muscle protein anabolism is best when supplements are taken in the morning.

Advice for caring for cancer patients

It is essential to warn patients early in the process of how the disease may affect nutritional status and the risk of malnutrition, even for overweight patients. If patients are convinced that a suitable diet will improve their well-being, they are more likely to accept and act on advice. The most reliable indicator is a stable weight, or at least stopping the downward spiral of weight loss already associated with severe illness.

For patients whose digestive functions are not affected, the advice is a varied high-protein (20% of total energy), high-calorie diet with over 40% fat (including omega 3) and 40% carbohydrate, including 10% fast-acting. It is best to eat little and often and to adapt meals to suit changes in taste, smell and so on. For patients whose throat is affected it may be necessary to modify the consistency of food to avoid pain or suffocation while ensuring sufficient calorie intake. For dry mouths, sip water with lemon at regular intervals and avoid over-dry food. For a loss of appetite, recommend three high-protein, high-calorie appetisingly-presented meals plus snacks.

To combat tiredness, make sure meals are quick and easy to prepare, small portions, high in vitamin C and sweet foods.

If the sense of taste is affected, colour, presentation and texture become all-important. Pay attention to seasoning, choose strong flavours and serve dishes hot. 

For patients with an aversion to food, it is advisable to rinse the mouth before eating, to favour bland dishes, steamed food, chicken, fish eggs and dairy. Avoid anything bitter (chocolate, coffee) or metallic (red meat).

In the event of nausea and vomiting, observe the most favourable times of day for eating and choose cold, odourless food, neither too fatty nor acidic or sweet.

La prise en charge précoce des effets secondaires en oncologie par une alimentation dédiée. Philippe Pouillart, Caroline Battu. Actualités pharmaceutiques n° 576 May 2018.