Neuroendocrine tumors (NETs) and diet: Which foods help manage symptoms?

As of today, no scientific evidence shows that changing one’s diet (such as a sugar-free diet, cutting out dairy, etc.) can slow down a neuroendocrine tumour (NET). Furthermore, drastic dietary changes can negatively impact health by depriving the body of essential nutrients.

Before making any changes to your diet, it is crucial to consult with your healthcare team.

Common dietary issues with NETs

Neuroendocrine tumours (NETs) or the side effects of their treatments can cause various unpleasant symptoms, often related to weight management and digestion:

Weight loss

If you are experiencing unintentional weight loss, consulting a dietitian is essential. There are various foods and methods to increase your intake of proteins or fats to help you maintain a stable weight.

Diarrhoea

In NET patients, diarrhoea may be caused by an excess of hormones, infections, treatments (including surgery), or certain foods. It is important to determine whether diarrhoea is temporary or persistent: dietary-induced diarrhoea is usually temporary, while the removal of the pancreas may cause long-term diarrhoea. Identifying the cause of diarrhoea is essential for effective treatment.

Steatorrhoea (fatty stools)

Steatorrhoea can result from somatostatin analog treatments or surgical interventions on the pancreas. In these cases, the body no longer fully absorbs fats, leading to abnormally fatty stools, which are often foul-smelling, pale, greasy, and sometimes frothy.

Other symptoms often associated with NETs include:

• Bloating and stomach heaviness,
• Heartburn,
• A sensation of feeling full very quickly,
• Dumping syndrome, which can occur after gastric surgery.

Dietary impact on carcinoid syndrome

Carcinoid syndrome is a group of symptoms that some NET patients may experience. It occurs when NETs, often in the small intestine (but potentially in other locations), spread to other parts of the body, typically the liver.

The main symptoms of carcinoid syndrome include:

• Diarrhoea,
• Skin flushing, particularly in the face,
• Stomach pain,
• Heart issues such as palpitations,
• Wheezing and shortness of breath.

Carcinoid syndrome arises when a NET leads to the overproduction and increased release of serotonin. An excess of serotonin in turn decreases tryptophan—an amino acid—in the body. Normally, tryptophan is converted into niacin (vitamin B3) in the body.

In cases of carcinoid syndrome, vitamin B3 levels can therefore become too low. Here are some tips to address this:

• Protein-rich foods contain a high level of tryptophan. It can be beneficial to consume lean meats, fish, eggs, low-fat dairy products, nuts, wheat-based protein products, and legumes.
• Your doctor may also recommend supplementing with a niacin tablet, perhaps through a B-vitamin complex.

On the other hand, some foods may trigger symptoms of carcinoid syndrome, such as abdominal pain, diarrhoea, or facial flushing. It’s helpful to keep a food journal to track meals and any related symptoms. For two weeks, note:

• Foods consumed,
• The amount and/or portion size,
• Any symptoms that appear after meals, if any.

Common carcinoid syndrome triggers include:

• Large meals,
• Fatty and spicy foods,
• Alcoholic beverages,
• Foods high in amines:
  • Aged cheeses,
  • Smoked, salted, or cured fish and meats,
  • Yeast extracts and brewer's yeast, hydrolysed proteins (such as wheat protein powder),
  • Soy products,
  • Sauerkraut,
  • Caffeinated drinks,
  • Chocolate,
  • Peanuts, Brazil nuts, coconut,
  • Raspberries, bananas, avocados, pineapple.

Dietary impact on functional pancreatic and duodenal NETs

Insulinomas (Pancreatic)

Insulinomas produce insulin uncontrollably, leading to lowered blood sugar. While dietary changes won’t affect the insulinoma itself, certain adjustments can help stabilize blood glucose levels.

The glycaemic index (GI) ranks foods containing carbohydrates based on their effect on blood sugar levels. Low-GI foods help maintain stable blood sugar and prevent spikes and drops in blood glucose.

>> Find more information on low-GI foods here <<

Gastrinomas (Pancreatic and Duodenal)

Gastrinomas produce the hormone gastrin, which stimulates the secretion of gastric acid. This hormone, produced and distributed by G cells in the stomach, small intestine, and pancreas, can cause digestive problems, nausea, diarrhoea, and weight loss.

If you have gastrinoma, a prescribed treatment will help reduce or even completely block gastric acid production. It is also recommended to avoid foods that may cause heartburn or digestive issues, such as:

• Large meals,
• Spicy foods,
• Citrus fruits,
• Fatty foods,
• High-fibre foods,
• Vinegar.

Glucagonomas

Glucagonomas produce large amounts of glucagon, a hormone that raises blood sugar. Glucagonomas can lead to various blood sugar-related issues, including diabetes.

If you have diabetes, it is essential to work with an endocrinologist to develop a suitable dietary plan.

VIPomas

VIPomas produce a mediator (vasoactive intestinal peptide) that causes watery diarrhoea. This can result in deficiencies of blood components such as potassium, phosphate, or bicarbonate, leading to muscle aches, general weakness, cramps, numbness and tingling in the limbs, and dehydration.

Certain foods can help restore potassium levels, including:

• Tomato juice,
• Prunes, bananas, oranges, figs, avocados,
• Kidney beans,
• Dried dates, apricots, and raisins,
• Nuts,
• Potatoes, etc.

Conclusion

In summary, while no specific diet can slow the progression of neuroendocrine tumours (NETs), dietary adjustments may help relieve certain symptoms. Tailoring your diet to the particular needs of each type of NET, by prioritizing or avoiding specific foods, can contribute to a better quality of life and help manage digestive, metabolic, or weight-related issues. Before making any dietary changes, consult your healthcare team to develop a safe, personalized approach.

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