This is the second article in the Neuroendocrine Cancer Nutrition series. In the first article, I focussed on Vitamin and Mineral deficiency risks for patients. Those who remember the content will have spotted the risks pertaining to the inability to absorb particular vitamins and minerals. This comes under the general heading of Malabsorption and in Neuroendocrine Cancer patients, this can be caused or exacerbated by one or more of a number of factors relating to their condition. It’s also worth pointing out that malabsorption issues can be caused by other reasons unrelated to NETs. Additionally, malabsorption and nutrient deficiency issues can form part of the presentational symptoms which eventually lead to a diagnosis of Neuroendocrine Cancer; e.g. in my own case, I was initially diagnosed with Iron Deficiency Anaemia. Even after diagnosis, these issues still need to be carefully monitored as they can manifest as part of the consequences of having cancer and cancer treatment.
Malabsorption will present via several symptoms which may be similar to other issues (i.e. they could masquerade as, or worsen, the effect of a NET Syndrome). These symptoms may include (but are not limited to) tiredness/fatigue/lethargy, diarrhea, steatorrhea (see below), weight loss. Some of these symptoms could be a direct result of nutrient deficiencies caused by the malabsorption. Some patients (and perhaps physicians?) could mistake these for symptoms of Neuroendocrine disease including certain syndromes, perhaps leading to prescribing expensive and unnecessary drugs when a different (and cheaper) strategy might be better.
Crash Course……. We eat food, but our digestive system doesn’t absorb food, it absorbs nutrients. Food has to be broken down from things like steak and broccoli into its nutrient pieces: amino acids (from proteins), fatty acids and cholesterol (from fats), and simple sugars (from carbohydrates), as well as vitamins, minerals, and a variety of other plant and animal compounds. Digestive enzymes, primarily produced in the pancreas and small intestine (they’re also made in saliva glands and the stomach), break down our food into nutrients so that our bodies can absorb them. If we don’t have enough digestive enzymes, we can’t break down our food—which means even though we’re eating well, we aren’t absorbing all that good nutrition.
The malabsorption associated with Neuroendocrine Cancer is most prevalent with the inability to digest fat properly which can lead to steatorrhea. Patients will recognise this in their stools. They may be floating, foul-smelling and greasy (oily) and frothy looking. Many patients confuse steatorrhea with diarrhea but technically it’s a different issue although both issues may present concurrently. Whilst we all need some fat in our diets (e.g. for energy), if a patient is not absorbing fat, it ends up being wasted in their stools and in addition to the steatorrhea, it can also potentially lead to (unwanted) weight loss and micronutrient deficiencies of the fat-soluble vitamins A, D, E and K. Certain water-soluble vitamins, particularly B3 and B12, are also at risk. Steatorrhea issues can be addressed by prescribing enzyme replacement therapy (PERT) products as directed by your doctors or dietician (e.g. Creon etc).
Structoral Changes (i.e. Surgery) can play a very big part in malabsorption issues. For example, if a patient has undergone Pancreatic surgery, this will most likely effect the availability of pancreatic digestive enzymes needed to break down food. Many Small Intestine NET (SINET) patients will suffer due to the removal of sections of their ileum, an area where absorption of water-soluble vitamins and other nutrients take place. In fact, the terminal ileum is really the only place where B12 is efficiently absorbed. Low B12 will cause fatigue. Although a less common tumour location, jejunum surgery could result in loss of nutrients as this section of the small intestine is active in digestive processes. Malabsorption issues for SINETs are an added complication to the issues caused by a shorter bowel (e.g. increased transit times), something which is regularly assumed to be the effects of one of the NET Syndromes (particularly diarrhea and fatigue).
Another risk created by the lack of terminal ileum is Bile Acids Malabsorption (BAM) (sometimes known as Bile Salts Malabsorption). Bile Acids are produced in the liver and have major roles in the absorption of lipids in the small intestine. Following a terminal ileum resection which includes a right hemicolectomy, there is a risk that excess Bile Acids will leak into the large intestine (colon) via the anastomosis (the new joint between small and large intestines). This leakage can lead to increased motility, shortening the colonic transit time, and so producing watery diarrhea (or exacerbating an existing condition). Although this condition can be treated using bile acid sequestrants, it is difficult to pinpoint it as the cause.
The Gallbladder plays an important part in the digestive system – particularly in fat breakdown. The liver continually manufactures bile, which travels to the gallbladder where it is stored and concentrated. Bile helps to digest fat and the gallbladder automatically secretes a lot of bile into the small intestine after a fatty meal. However, when the gallbladder is removed, the storage of bile is no longer possible and to a certain extent, neither is the ‘on demand automation’. This results in the bile being constantly delivered/trickled into the small intestine making the digestion of fat less efficient. One of the key side effects of Somatostatin Analogues (Octreotide and Lanreotide) is the formation of gall stones and many Neuroendocrine Cancer patients have their gallbladder removed to offset the risk of succumbing to these issues downstream. Removal of the gallbladder also increases the risk of BAM as described above. Any issues with Bile Ducts can also have a similar effect.
The Liver has multiple functions including the production of bile as stated above. However, one of its key functions within the digestive system is to process the nutrients absorbed from the small intestine. If this process is affected by disease, it can potentially worsen the issues outlined above.
Evidence of the problems being caused by the effects of small intestinal surgery can be found in a recently published Swedish study which you can read here: Click here. This particular study recommends supplementation of B12 and D3 for those affected. If you’re having trouble getting your physician to monitor your vitamin levels, show them these studies.
Somatostatin Analogues can also impact (or worsen) the ability to digest fat as they inhibit the production of pancreatic digestive enzymes. This is a well-known side effect of both Octreotide and Lanreotide.
The levels of the fat-soluble vitamins (ADEK) and B vitamins such as B12, need to be monitored through testing and/or in reaction to symptoms of malabsorption. If necessary these issues need to be offset with the use of supplements as directed by your dietician or doctor. Supplements are less affected by malabsorption of nutrients but their efficiency can be impacted by fast gut transit times (thus why testing is important). The evidence and recommendations for malabsorption caused by somatostatin analogues is here: Click Here.
Deficiencies of these vitamins and certain minerals can lead to other conditions/comorbidities, some more serious than others. For a list of the vitamins and minerals most at risk for Neuroendocrine Cancer patients, have a read of my article – Vitamin and Mineral deficiency risks.
There is a third article in this series discussing a related issue with Neuroendocrine Cancer, particularly where gut surgery has been performed. You can link directly to this article here – “Gut Health” – (Gut Health, Probiotics and Small Intestinal Bacterial Overgrowth (SIBO)).
The fourth article looks at Amines and why they can cause food reactions or exacerbate syndromes.
Again, I remain very grateful to Tara Whyand for some assistance. This is a big and complex subject and I only intended to cover the basics. If you need professional advice, you should speak to your doctor or dietician.
Thanks for listening
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