Nutritional deficiencies are common in coeliac disease and should be identified and treated (McLoughlin, 2003). Nutritional deficiencies present upon diagnosis will depend on the amount of time the patient has been suffering from untreated coeliac disease, the extent of damage to the gastrointestinal tract and the amount of malabsorption (Niewinski, 2008).

CREST guidelines recommend testing serum ferritin, vitamin B12 and folate, all of which are deficiencies commonly found in newly diagnosed coeliacs. Coeliacs should be encouraged to consume high amounts of iron and folate containing foods to combat these deficiencies (WGO, 2007) and supplementation should be considered if recommended intakes cannot be achieved through diet alone (McLoughlin, 2003). Calcium and vitamin D deficiencies may also be common upon diagnosis and supplementation may be necessary if intake is insufficient.

Other nutritional deficiencies which may be present at diagnosis of coeliac disease include magnesium, zinc, niacin, riboflavin (Kupper, 2005) and in cases of classic malabsorption fat soluble vitamin deficiencies may be seen (Niewinski, 2008). However, most nutritional deficiencies will resolve once a gluten-free diet is established due to increased absorption as a result of mucosal healing.

The gluten-free diet itself can be associated with lower levels of certain micronutrients with one study finding a poor vitamin status in 56% of coeliacs (Hallert, 2002). Fibre, iron, calcium, vitamin D, vitamin B6, vitamin B12 and folate deficiencies have all been described in people following a gluten-free diet. Gluten-free foods themselves have been shown to be lower in thaimin, riboflavin, niacin, folate, iron and dietary fibre. This may be primarily due to the fact that gluten-free foods tend not to be fortified and tend to be refined. The most common nutritional deficiencies are outlined here.

Lack of fibre

A gluten free diet can be lower in fibre than normal diets and as such can lead to the discomfort of constipation. This may be due to the fact that gluten-free products tend to be refined and wholegrain varieties contain less fibre than their wholegrain gluten-containing counterparts. Patients need to focus on choosing higher fibre prescribable gluten-free products and those naturally occurring gluten-free foods that are high in fibre including grains such as corn, millet, brown rice, amaranth, buckwheat and quinoa and a wide variety of fruit and vegetables. Adequate fluid intake and exercise are also important to prevent constipation.