Why Untreated Celiac Disease Can Cause Malnutrition

Untreated celiac disease can cause malnutrition — even if you’ve been eating a healthy, balanced diet. That’s because you may not have been absorbing many of the nutrients in the foods you were eating.

Photo of an empty plate with a knife and fork crossed
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The real work of absorbing nutrients from food is performed by the lining of your small intestine — specifically by the intestinal villi, which are tiny, hair-like tentacles on the lining of the small intestine.

When someone who has celiac disease consumes foods containing gluten, the body reacts by attacking the intestinal villi. Eventually, those tiny tentacles can be completely flattened, leaving them unable to do their job of absorbing nutrients.

It doesn’t matter how well you eat — if your villi have been destroyed by untreated celiac disease you’re almost certain to be malnourished, and that puts you at risk for anemia, weight loss, osteoporosis, and infertility. In addition, children with untreated celiac disease often suffer from short stature caused by malnutrition.

Common Deficiencies Leading to Malnutrition

Untreated celiac disease patients may be deficient in these specific nutrients:


Iron deficiency anemia is common in people with untreated celiac disease, and in fact, many physicians routinely test for celiac when a patient suffers from unexplained anemia, a deficiency in the red blood cells needed to carry oxygen throughout the body. Symptoms of anemia include fatigue, weakness, shortness of breath, dizziness, pale coloring, feeling cold frequently, a rapid pulse and palpitations.

Vitamin D, Calcium, and Magnesium

The small intestines also absorb vitamin D, which is absolutely essential for bone growth. Vitamin D deficiency is common in people with celiac, and the nutrient is necessary to properly absorb the bone-building nutrients calcium and magnesium.

Adults with untreated celiac disease may lose bone mass and even develop osteoporosis because their bodies can’t absorb these nutrients, even if they’re consuming enough of them. Children, meanwhile, may not develop proper bone mass in the first place. Supplements don’t help because the body can’t absorb them.


Folate, a B vitamin, is absorbed in the last part of the small intestine, an area that’s often damaged by celiac disease. Folate helps produce new cells and is particularly important in pregnancy and early childhood.

Deficiencies can cause folate deficiency anemia (which is different from iron deficiency anemia), along with serious birth defects such as Spina Bifida and anencephaly.

Vitamin B12

The last part of the small intestine also absorbs vitamin B12, and untreated celiac disease patients often have deficiencies in this vitamin as well as folate.

Vitamin B12 deficiency causes diarrhea and/or constipation, fatigue, and loss of appetite, and can lead to more serious neurological symptoms, such as confusion, depression, loss of balance and nerve damage in hands and feet.

Fatty Acids

Untreated celiac disease patients often excrete fat in their stool because their small intestines cannot absorb it. This leads to deficiencies in omega-6 and omega-3 fatty acids such as linoleic and linolenic acid, which control inflammation and blood clotting and may contribute to heart disease prevention.

The brain contains high concentrations of several essential fatty acids. People with low levels risk fatigue, poor memory, and mood swings. Medical researchers also have reported cases of deficiencies in vitamin A, vitamin E, and vitamin K in celiac disease patients. All of these vitamins are fat-soluble.

After Starting a Gluten-Free Diet

Once you start eating gluten-free, levels of all these nutrients should begin to return to normal, correcting your malnutrition. For example, many celiac disease patients reverse their iron deficiency anemia after about a year on the diet as their intestinal villi recover, and bone mass begins to recover in the same time frame.

In some cases, though, you may want to consult with your physician about supplementing to raise some of your nutrient levels more quickly. Medical testing for levels of specific nutrients can help pinpoint deficiencies and provide guidance for supplementation.

However, physicians caution that you shouldn’t take supplements to correct the malnutrition caused by celiac disease without a doctor’s guidance, since it’s possible to take too much of certain nutrients, potentially making the situation worse, not better.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Celiac Disease. Consumer Information Sheet. National Digestive Diseases Information Clearinghouse. 

  2. Anemia – B12 Deficiency. Consumer Information Sheet. National Institutes of Health.

Additional Reading
  • What People with Celiac Need to Know About Osteoporosis. Consumer Information Sheet. National Institute of Arthritis and Musculoskeletal and Skin Diseases. 

By Jane Anderson
Jane Anderson is a medical journalist and an expert in celiac disease, gluten sensitivity, and the gluten-free diet.