Key Nutritional Deficiencies
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).
REST 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.
Iron deficiency anaemia is one of the most common indicators of coeliac disease (Hill et al, 1999). It may also occur while following the gluten-free diet. A survey undertaken in the USA in 2005 found that 56% of women on a gluten-free diet were not meeting the RDA for iron (Thompson, 2005).
Enriched, fortified cereal products contribute a large percentage of iron to the diet. However, gluten-free products tend not to be fortified and studies have shown that gluten-free cereal products generally provide lower amounts of iron (Thompson 1999, 2000). It may be necessary for the client to take an iron supplement initially upon diagnosis. However, a dietary review by a dietitian is paramount to ascertain the iron content of the client’s gluten free diet and for advice on habitual iron sources other than gluten-free products. If iron supplements are necessary they should be eaten on an empty stomach for optimal absorption and should not be taken at the same time as calcium supplements as they will inhibit the absorption of the iron supplement.
Calcium deficiency and Osteoporosis
Calcium deficiency is common among newly diagnosed coeliacs. This is thought to be primarily an effect of chronic malabsorption prior to diagnosis of coeliac disease. Calcium malabsorption can cause a reduction in bone mineral density (BMD) which may lead to osteoporosis.
Osteopenia is thought to be prevalent in 70% of adults with untreated coeliac disease (Botha & Rostrami, 2005). Furthermore, McFarlane et al, in 1995 showed that 50% of people on a gluten-free diet still had osteoporosis. A reduced calcium intake following diagnosis may be as a result of gluten-free bread and cereal foods not being fortified, as studies suggest that 30% of daily calcium intake comes from these foods. Adult coeliac patients with a lower BMD have been found to have a lower intake of calcium (860mg) than those with a normal BMD (1054mg). Hence, dietary advice on adequate calcium intake is also crucial for those with coeliac disease.
There is controversy surrounding the degree of calcium intake required in coeliac disease to prevent osteoporosis. The British Society of Gastroenterology (2007) recommend that as there is only a small increase facture risk in coeliac disease that 1000mg/day should be sufficient for adults with coeliac disease, with a higher intake of 1200-1500mg/day recommended for post-menopausal women and men >55years. However, the British Society of Gastroenterology (2010) recommend an intake of 1500mg calcium/day for adults with coeliac disease. Clinical judgement should be used when advising on calcium intake in coeliac disease, with the higher intake of 1500mg/day likely to be adequate for all coeliacs. A review of the calcium intake through the diet should be carried out by a dietitian to ensure that inadequate or excessive amounts of calcium are not being consumed by clients. If sufficient calcium intake cannot be achieved through diet alone a calcium supplement may be required.
There are no alternative recommendations for a higher calcium intake in children with coeliac disease. The gluten-free diet in children leads to recovery of bone mineralisation to normal levels and studies suggest that early diagnosis and treatment of coeliac disease may prevent the development of osteoporosis (Bardella, 2000).
There are also no specific recommendations for calcium intake in pregnant and lactating women with coeliac disease and advice should be given on an individual case basis.
Coeliacs suffering from secondary lactose intolerance may at particular risk of developing calcium deficiency as they may temporarily avoid dairy foods. It is important to ensure calcium requirements are met by including non-dairy calcium foods, e.g. calcium fortified soya milk, in the diet. Secondary lactose intolerance usually resolves when the gut heals and lactase can be produced in sufficient amounts to break down the lactose.
Vitamin D Deficiency
Vitamin D deficiency is also common in newly diagnosed coeliacs due to intestinal malabsorption. As vitamin D deficiency can reduce BMD and is required for efficient absorption of calcium it is essential that adequate vitamin D status is achieved. Clients also need to be educated on adequate amounts of vitamin D, especially in the light of recent evidence indicating that, as a nation, our Vitamin D levels are already low (McCarthy et al, 2006) due to our Northern latitude, lack of sunshine and poor intake of vitamin D rich foods such as oily fish.
The vitamin D requirements for people with coeliac disease are the same as for the general population; however, it is essential to achieve these requirements due to the increased risk of osteoporosis in coeliac disease. If adequate intake of vitamin D cannot be achieved supplementation may be recommended, particularly in elderly people who do not have much exposure to sunlight and in some ethnic groups (CREST, 2006).
Vitamin B Deficiency
For a number of reasons, B vitamin deficiency is more recently of concern. A survey of people with coeliac disease over a 10 year period showed that 50% showed signs of poor B vitamin status (Hallert et al, 2002). This paper has queried the link to elevated homocysteine levels which is a known risk factor for heart disease. The main vitamins of concern in this paper were folate, vitamin B6 and vitamin B12.
A paper by Thompson et al, 2000, highlighted that gluten-free cereal foods are generally also low in B vitamins such as Folate, B12, Thiamin, Riboflavin, Niacin and B6. From a public health perspective, the most crucial vitamin here is folate for the protection of the foetus against neural tube defects. One study found that over half of all women with coeliac disease consumed less than the recommended amount of folate. As coeliacs are at an increased risk of folic acid deficiency they are at an increased risk of having a child with a neural tube defect. The GP and dietitian must be active in educating female coeliac clients on the need to take adequate folic acid. The recommendation for women with coeliac disease is the same as that of the general population, i.e. a 400µg folic acid supplement daily for women planning a pregnancy or in their first trimester of pregnancy. There may be a case for a further increase in requirements of folate pre-conceptually or during the first trimester of pregnancy in patients with coeliac disease if there is a history of folate deficiency prior to diagnosis; however, evidence is limited in this area. Vitamin B12 deficiency must also be kept in mind in relation to the elderly and vegetarians.
The emphasis of dietary management in coeliac disease should focus on the nutritional quality of the diet and not simply ‘foods allowed or foods to avoid’.
The key elements of managing the coeliac disease through diet are:
- Choose and eat foods that are gluten-free
- Consume a well balanced diet; including good sources of calcium, iron, vitamin D and B vitamins
- Eat foods that are rich in fibre
- Always check foods and fluids in the Coeliac Society List of gluten-free foods and check the food labels