Fruits wastebasket

Fructose malabsorption and other dangers of a plant-based diet

Photo by Jo Sonn on Unsplash

The plant-based diet is widely popular. Thousands of documentaries and articles argue that humans are striving on a plant-based diet. Athletes are performing better and recovering faster if they consume plant protein. The risk of cardiovascular disease is lower for vegans. I know you’ve heard it a thousand times before: fruits are a healthier choice compared to sugar.

Is it always the case?

Jennifer is a mother of three young girls from seven to one. She suffers from a functional digestive disorder. Dozens of doctors examined her, she has completed multiple procedures to examine her gastrointestinal system, and all the tests came back normal. However, severe symptoms are interfering with Jennifer’s daily living. Her gut is continuously hurting, distended, and making noises. She feels bloated, tired, crampy, constipated most of the time. She is embarrassed. Jennifer has acid reflux so intense it burns her throat and affects her voice. Jennifer struggles with an excess of mucus in her throat. Is she reacting to fruits?

Gastroesophageal reflux disease (GERD), Laryngopharyngeal Reflux ( LPR), Irritable bowel syndrome (IBS), gluten intolerance, lactose intolerance, fructose intolerance, hormone imbalance, postnasal drip — diagnosis and abbreviations are quickly adding up. No treatment seems to bring Jennifer relief. Some interventions are improving the symptoms, but in the end, it all comes back, it weighs heavily on her quality of life.

Jennifer is not alone; an estimated 10%-20% of the world’s population is affected by IBS. This condition is common among people aged 20–30 years old, and, according to statistics, IBS is more common in women than men.

Doctor Jonathan a gastroenterologist; he is Jenniffer’s last hope to find the solution. Her symptoms are causing her anxiety, depression, and embarrassment, and Dr. Jonathan knows it. Dr. Jonathan works in a major teaching hospital; he is interested in the new research. He is very knowledgeable and caring; his excellent bedside manners and friendliness are palpable. If you meet him, he is easy to like. Dr. Jonathan is following Jennifer’s case, but he doesn’t have all the answers. Empirically he prescribed treatments like proton pump inhibitors, acid fighting barrier drugs, tricyclic antidepressants, medication for neuropathy. Nothing seems to do the trick in Jennifer’s case.

Functional gastrointestinal disorders are only diagnosed when tests for severe or life-endangering conditions come back normal. Dr. Jonathan ruled out such conditions by completing gastro endoscopy, a biopsy of upper digestive tract, stool test, 24 hours acid monitoring test. Doctors assume that patients are suffering from so-called visceral hypersensitivity.

It doesn’t mean that symptoms are in Jennifer’s head; it means that her stomach and digestive tract are firing up and malfunctioning for no apparent reason. That is what Dr. Jonathan told Jennifer. After years of treating her symptoms, Dr. Jonathan recommends a low-FODMAP diet.

The low-FODMAP diet is a relatively new approach to treat functional digestive disorders like irritable bowel syndrome. The scientist from Monash University pioneered in FODMAP research in the area of functional gastrointestinal disease. What researchers discovered is that a low FODMAP diet ( restriction in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) alleviates symptoms in 80% of patients with IBS. Research shows that many humans have a problem digesting fibers, but people like Jennifer are reacting to specific fibers intensely. Dietary short-chain carbohydrates are poorly absorbed in her small intestine, fermented in the large intestine, causing symptoms like gas, cramps, pain, excessive acid in the stomach, feeling of hardness in the stomach, constipation.

FODMAPs? Sounds complicated

Management with a low FODMAP diet is challenging to follow. Short-chain carbohydrates are everywhere.

Fructose is for “F” in FODMAP. Certain fruits, honey, and some high fructose corn syrup contain more fructose than glucose. Fructose is a monosaccharide; it attracts water into the bowel and causes an osmotic effect. Around 30%-40 % of people suffer from fructose malabsorption. Fructose is better absorbed in the presence of glucose. Some fruits have a high fructose/glucose ratio and are challenging to digest.

Banana is low FODMAP ( Image by Anna DeVeaux)
Grapefruit is low FODMAP ( Image by Anna DeVeaux)

Lactose is a sugar found in milk; it is a disaccharide. The small intestine of healthy people produces an enzyme to help break down lactose. The majority of adults today are deficient in this enzyme and have faulty absorption of lactose.

Polyols are for “P.” Fruits, vegetables, and artificial sweeteners contain polyols. It is safe to assume if the name of a sweetener ends by “ol” ( sorbitol, mannitol) — it is a polyol. The majority of people with IBS will benefit from sorbitol restriction. Polyols are like fructose, simple sugars that attract water into the bowel and cause abdominal pain.

Oligosaccharides are for “O.” Oligosaccharides as fructans (FOS) and galactooligosaccharides (GOS) found in wheat, rye, onions, garlic, legumes, and lentils. Humans have no enzymes in their digestive tract to digest oligosaccharides. Oligosaccharides are universally faulty absorbed by humans and known to produce gas in the large intestine.

If your Dr recommends trying the low-FODMAP diet to manage IBS at first, you will panic. It is incredibly complicated and restricting. You may feel that everything has FODMAPs in it. What do you need to avoid? Fruits containing fructose are apples, apricots, blueberries, cherries, dates, figs, mangoes, and others. If the fruit has a pit, most likely, it is high in FODMAPs. Vegetables containing fructans include artichoke, asparagus, broccoli, celery, corn, fennel, and others. Wheat, rye, couscous, amaranth, barley are known to be the source of fructans, GOS, and gluten and may be difficult to digest for patients with IBS. Milk and other dairy products are a source of lactose should be avoided in the elimination phase of the low-FODMAP intervention. Nuts like cashews are high in fructans and GOS may aggravate intestinal symptoms as well.

Patients like Jennifer experience gastrointestinal symptoms because they have difficulty absorbing many or most of the FODMAPs. Gut hypersensitivity also means certain people are more sensitive to gas produced during digestion of certain sugars.

FODMAP simplified ( Image by Anna DeVeaux)

In cases like Jennifer’s, it is a promising and safe approach to try 2–6 weeks of low-FODMAP diet to understand whether or not restricting FODMAPs can help to manage symptoms of IBS. Peter Gibson from Monash University, pioneered the FODMAPs research ten years ago. He is continuing groundbreaking work to further evaluate and test a low-FODMAP intervention with the hope of helping to alleviate gruesome symptoms of patients with IBS like Jennifer.

Ask your Dr about FODMAPs.

learner, writer, biotech investor, research translation, drug development, genetics. 4-lingual.

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