Possible risks and side effects of the gluten-free diet for non-coeliacs

Apart from for people with coeliac disease and non-coeliac gluten sensitivity, there is no medical consensus on prescribing the gluten-free diet for other health problems. But other conditions have also been linked to gluten-containing foods, although the connection is yet to be fully understood. That is the case with irritable bowel syndrome (IBS), a common digestive disorder.  

One study published by the International Journal of Colorectal Disease showed that around one third of people who suffer from IBS have seen improvements in their condition when switching to a gluten-free diet. More research is needed, however, to determine which of those individuals are benefiting from avoiding gluten, or from the effects of eating fewer carbohydrates, particularly a specific type of fermentable carbohydrates called FODMAPs, which are also found in wheat, barley, and rye.  

In some people, it appears that gluten causes the gut lining cells to release zonulin, a protein that can push apart the tight connections between the cells that line the small intestinal cell wall. .   

Other research has shown that gluten may play a role in increased intestinal permeability, sometimes known as ‘leaky gut’, which is known to play a role in gastrointestinal conditions such as coeliac disease, Crohn’s disease, and IBS. Some research also suggests that leaky gut may be associated with other autoimmune diseases (type 1 diabetes, lupus and multiple sclerosis), chronic fatigue syndrome, arthritis, fibromyalgia, allergies, asthma, acne, obesity and even mental illness. But more research is needed to establish a clear cause-effect mechanism. 

For these reasons and others, many people have adopted the gluten-free diet.  

Avoiding gluten will probably have no particular effect on your health if you do not have coeliac disease or non-coeliac gluten sensitivity (NCGS). It may help you if you suffer from IBS, but that is by no means a certainty. There are no known side effects from going back to eating gluten after being gluten-free, unless, of course, you have coeliac disease or NCGS. 

However, if you think you might have coeliac disease or NCGS, it is important to consult with a doctor before adopting a gluten-free diet. This is because it is very difficult to diagnose either of these two conditions if you have not been eating gluten for a while.  

If you decide to go gluten-free even though this is not a treatment you have been told to follow for a specific health reason, it can become harder to eat a fully balanced diet. 

Lack of fibre 

For many people, wheat is a major source of dietary fibre, which is essential for properly functioning bowels. In developed countries, the average diet is lacking in fibre, so anyone avoiding many of the most common grains will have to make up for this by including more gluten-free grains, beans, legumes, nuts, seeds, vegetables, and fruit. A gluten-free diet can healthy and balanced, but it tends to require more work in terms of sourcing and preparing your food.   

Nutritional deficiencies 

Fortified breads and cereals are a major source of B vitamins for many people, but gluten-free flours are usually not fortified. Vitamin B9, commonly known as folic acid, is important for everyone, especially women who are pregnant or about to conceive. Many doctors recommend that people on a gluten-free diet also take multivitamin supplements to avoid nutrient deficiencies. 

Weight gain 

A person who has had coeliac disease and switches to the gluten-free diet will probably gain weight as their intestine recovers from the damage caused by the autoimmune reaction and absorption of nutrients improves. For those without celiac disease, weight gain may also occur, but for different reasons. Gluten-free processed foods sometimes have a more carbohydrates and fat to improve their ‘mouthfeel’,  so, like any diet high in processed foods, this is not the healthiest option.   

To make sure you eat plenty of fibre, eat as many gluten-free whole grain products as you can. Among staples, choose brown rice over white rice, and include other grains like quinoa, millet, or buckwheat.  . Fruits, vegetables, beans, and legumes are also good providers of fibre in the diet.  

For vitamin B9 (folate), eat plenty of broccoli, dark leafy greens, asparagus, citrus fruits, peanuts, avocado, and beans, and lentils. Seeds, nuts, dairy food and meat are all good sources of other B vitamins.