Symptoms of Malabsorption


Malabsorption refers to a wide range of disorders that affect the body’s ability to absorb nutrients from the food you eat. Nutrients that are not absorbed properly may include micronutrients (vitamins and minerals), macronutrients (carbohydrates, proteins and fats), or both.

It is important to identify the symptoms of malabsorption and get the correct treatment because untreated malabsorption can lead to malnutrition and nutrient deficiencies. 

Malabsorption may arise from food intolerances or various gastrointestinal diseases that affect your digestive system. Malabsorption may also be the result bacteria overgrowth.1 Some causes include:

Digestive symptoms

Digestive symptoms are the most common early symptoms of malabsorption. However, if these symptoms are ignored for a long time, symptoms of malnutrition will appear. 

Abdominal pain

Abdominal pain is pain anywhere in the belly. The feeling and severity of abdominal pain will vary depending on the malabsorption issue. 

Abdominal pain may be:

  • Dull or sharp
  • Localised (in one area) or generalised (all over)
  • Constant or intermittent

Abdominal pain is a common occurrence for all types of malabsorption issues including: 

  • Crohn’s disease 
  • Whipple’s disease 
  • Coeliac disease 

Bloating and gas

Although bloating and gas may be caused by other factors, such as eating too fast, these symptoms may indicate malabsorption, particularly when they are persistent and recurring. Bloating and gas may suggest the malabsorption of certain sugars.2


Watery, loose stools indicate the malabsorption of carbohydrates. When carbohydrate is not absorbed properly, it attracts water and leads to a build up of liquid in the gut, which causes diarrhoea.3 

A certain type of diarrhoea known as steatorrhea can also indicate the malabsorption of fat and some water-soluble vitamins (vitamins A, B and C). When an individual has steatorrhea, their stools may be covered with a greasy film. Steatorrhea may also cause stools which are:

  • Pale
  • Foul-smelling
  • Floating
  • Bulkier 


Constipation refers to irregular, infrequent, or difficult bowel movements. In particular, constipation can occur during malabsorption, and may even be intermittent with diarrhoea. 

Nutrient deficiencies

Vitamin deficiencies

Vitamin B12 deficiency

Vitamin B12, a water-soluble vitamin, is particularly important for your body. This vitamin helps keep the nervous system healthy, produce red blood cells, and create DNA and RNA (which provide ‘instructions’ to every cell in the body). 

When your body does not get enough vitamin B12, you may experience:

  • Fatigue
  • Mouth ulcers
  • Depression
  • ‘Pins and needles’ sensations
  • Shortness of breath

Although these may be signs of other problems, it is important to speak to your healthcare provider if  you have these issues. 

Severe cases of vitamin B12 deficiency may be caused by pernicious anaemia, an autoimmune disease where your own immune system attacks specific stomach cells required for vitamin B12 absorption. 

Vitamin D deficiency 

Vitamin D helps keep your bones, muscles, and teeth healthy by regulating calcium and phosphate levels in your body. 

A vitamin D deficiency in children can increase the risk of rickets, a condition which affects how bones grow leading to bone deformities. In adults, not getting enough vitamin D can cause a condition called osteomalacia, which causes pain in the bones and muscles. 

People with malabsorption disorders have a higher risk of low vitamin D, which can be caused by lack of sunlight exposure, an inability to absorb vitamin D, or both.4

Mineral deficiencies

Iron deficiency

Iron plays an important role in creating a protein called haemoglobin. Iron binds to this protein in red blood cells and carries oxygen around the body, improving mental function and immune function. 

Some adults referred for unexplained iron deficiency are diagnosed with coeliac disease.1 This is an autoimmune disorder where the immune system damages someone’s gut when they eat gluten, leading to malabsorption.. 

Iron deficiency symptoms can be very similar to those of vitamin B12 deficiency, and can include:

  • Fatigue
  • Weakness
  • Dizziness
  • Strange food cravings (e.g. dirt, sand)
  • Shortness of breath
  • Rapid heartbeat

Calcium deficiency

Calcium is mostly stored in bones, but it is also present in blood to help your heart, muscles and nerves function properly. Hypocalcaemia means the calcium levels in your blood are too low. Calcium deficiency can be detrimental to bone health, leading to the onset of rickets, osteomalacia and osteoporosis.

People with a mild calcium deficiency usually have no symptoms. However, when symptoms do appear, they can include:

  • Muscle cramps
  • Dry skin
  • Brittle hair and nails
  • Confusion
  • Memory issues
  • Irritability 

Weight loss and malnutrition

Unexplained weight loss

Losing 5% or more of your body weight unintentionally within 6-12 months can be classed as ‘unexplained’ weight loss.5 If this occurs, it is important to see your GP for medical advice. This is because an underlying malabsorption syndrome could be causing the problem, even if you are eating sufficient amounts of nutrients. Unexplained weight loss is most common when your body is unable to absorb macronutrients like carbohydrates, fats, and proteins.  

Failure to thrive in children

Failure to thrive (FTT) occurs when a child is not developing or growing at the normal rate. When a child’s weight is below the 2nd centile for their age, or when they have a slow rate of weight gain, they could be considered malnourished and may be failing to thrive.6 

FTT can also be caused by many factors other than malabsorption, including excessive energy expenditure due to Down’s syndrome and eating disorders. However, those with malabsorption issues are at an increased risk of developing FTT. FTT may have further complications (e.g., decreased intellectual ability) if left untreated.7 

Treatment for children with malabsorption issues includes:

  • Fortification of food
  • Correct management of malabsorption syndrome
  • Supplements
  • Frequent snacks and regular meals

Muscle wasting

As the name suggests, this is when the muscles waste away and reduce in size. Muscle wasting may be characterised by:

  • Muscle weakness in at least one limb
  • One of your arms or legs being significantly smaller than the other

Common treatments for those with muscle wasting attributed to malabsorption will include nutritional supplements. However, doing more physical activity may also help the muscle increase in size. 

Other symptoms


Anaemia is caused by a lack of oxygen-carrying red blood cells, and can make you feel tired and weak. Iron-deficiency anaemia (anaemia linked to low iron levels) can be caused by excessive bleeding, certain medications and malabsorption issues.8


When your body cannot absorb the required nutrients and energy from food, fatigue can be your body’s way of conserving the little energy it gets. Fatigue is a common symptom of chronic, untreated malabsorption. 

Skin rash

Rashes on the skin can occur as a result of different malabsorption syndromes, such as coeliac disease and inflammatory bowel disease (IBD). For those with coeliac disease, a common skin symptom is dermatitis herpetiformis, which is distinguished by red, raised patches that may turn into blisters that burst when scratched. IBD may cause recurring mouth ulcers as well as erythema nodosum which causes tender, red nodules under the skin. 

Skin issues may also occur alongside other malabsorption problems. This is because some vitamin deficiencies may induce skin problems. For example:

  • Yellow skin and vitiligo may indicate a vitamin B12 deficiency
  • Psoriasis may indicate a vitamin D deficiency


Malabsorption is an umbrella term for many conditions which affect the body’s ability to absorb nutrients from food. A variety of symptoms may occur in individuals with malabsorption, including: diarrhoea, constipation, weight loss, and nutrient deficiencies. Symptoms may vary depending on the specific malabsorption syndrome. 

Some people may experience similar symptoms temporarily, which may not be signs of a malabsorption problem. However, if the symptoms persist or recur, it is important to seek medical advice from a health professional. 


  1. Owens SR, Greenson JK. The pathology of malabsorption: current concepts. Histopathology [Internet]. 2007 Jan [cited 2023 Mar 30];50(1):64–82. Available from: 
  2. Fernández-Bañares F, Rosinach M, Esteve M, Forné M, Espinós JC, Maria Viver J. Sugar malabsorption in functional abdominal bloating: A pilot study on the long-term effect of dietary treatment. Clinical Nutrition [Internet]. 2006 Oct 1 [cited 2023 Mar 30];25(5):824–31. Available from:  
  3. Pietzak MM, Thomas DW. Childhood malabsorption. Pediatrics in Review [Internet]. 2003 Jun 1 [cited 2023 March 30];24(6):195-204. Available from: 
  4. Margulies SL, Kurian D, Elliott MS, Han Z. Vitamin D deficiency in patients with intestinal malabsorption syndromes - think in and outside the gut: Malabsorption and vitamin D deficiency. Journal of Digestive Diseases [Internet]. 2015 Nov [cited 2023 Mar 30];16(11):617–33. Available from:
  5. Wong, CJ. Involuntary weight loss. Med Clin North Am. 2014 [cited 2023 Mar 30];98:625-43. Available from: 
  6. Faltering Growth [Internet]. NICE. [cited 2023 Mar 30]. Available from: 
  7. Smith Z. Faltering growth. Clinical paediatric dietetics [Internet]. 2007 Jan 1 [cited 2023 Mar 30]:556-65. Available from:  
  8. Fernández-Bañares F, Monzón H, Forné M. A short review of malabsorption and anemia. World J Gastroenterol [Internet]. 2009 Oct 7 [cited 2023 Mar 30];15(37):4644–52. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Kristy Maskell

Master of Science – Nutrition and Dietetics, University of Hull
Bachelor of Science with Honours – Exercise and Health Science, University of Brighton

Kristy is a Dietetics master’s student which has allowed her to develop clinical knowledge of nutrition for a variety of populations. She is passionate about making evidence-based nutrition information accessible and loves to write this for everybody to read. Kristy looks forward to qualifying as a registered dietitian in the near future and having the opportunity to provide the best possible patient-centred care.

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