Food and Behaviour Research

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4 May 2017 - Food Navigator - Should the gluten-free craze come to an end? Study thinks so

Emma Jane Cash

Gluten-free diets should not be encouraged for those without coeliac disease, as restricting gluten may result in low intake of beneficial nutrients found in whole grains, say researchers.

A 24-year long study published in The BMJ this week has said people without coeliac disease shouldn't be cutting out gluten from their diets as it could mean they are missing out on "heart healthy" whole grains.

The researchers warn that "promotion of gluten-free diets for the purpose of coronary heart disease prevention among asymptomatic people without coeliac disease should not be recommended".

The trend of gluten-free or low gluten diets has increased recently due to beliefs that gluten can cause risk of chronic conditions such as coronary heart disease.

A growing trend

Gluten is a storage protein found in wheat, barley, rye and oats, and can cause inflammation and intestinal damage to those with coeliac disease.

Sufferers of coeliac are also at a higher risk of coronary heart disease, which can be reduced with a gluten-free diet.

Recently, growing worry has formed that gluten can have detrimental health effects including heart disease, obesity, metabolic syndrome and neuropsychiatric symptoms, regardless of coeliac status.

It is as a result of these concerns that the trend of gluten-free has become so popular.

According to the National Health and Nutrition Examination Survey (NHANES), the adoption of a gluten-free diet by non-coeliac sufferers has risen more than threefold from 0.52% of people to 1.69%, since 2009-10 to 2013-14.

In 2013, 30% of US adults said they were trying to minimise, or cut out completely, their gluten intake, despite the much higher prices of gluten-free alternative foods.

Say yes to gluten

The study found that for mean daily estimated intake of gluten at baseline was 7.5g for women and 10g for men in the highest fifth and 2.6g for women and 3.3g for men in the lowest fifth.

it was found that gluten intake correlated inversely with alcohol intake, smoking, total fat intake and unprocessed red meat intake.

However, gluten intake correlated positively with whole grain intake and refined grain intake.

Coronary heart disease was diagnosed for 6,529 participants, fatal myocardial infarction developed in 2,286 participants and non-fatal myocardial infarction developed in 4,243 participants.

In the lowest fifth of gluten intake, coronary heart disease was measured at an incident rate of 352 per 100,000 person years, whereas in the highest fifth the incident rate was 277 per 100,000 person years.

No significant association between estimated gluten intake and either fatal myocardial infarction or non-fatal myocardial infarction was found.

The lack of association was the same for gluten intake and coronary heart disease risk, for both men and women.

The study concluded that avoiding gluten had no effect on risk of coronary heart disease but did mean participants may be avoiding whole grains which have cardiovascular benefits.

The study

The US based researchers monitored just over 110,000 healthy participants with food questionnaires every four years from 1986 to 2010.

Participants were excluded if they had diagnosis of myocardial infarction, angina, stroke or coronary artery bypass graft surgery, or cancer.

Those with a diagnosis of coeliac were also excluded.

The food questionnaires asked participants about their food items and portion sizes. The researchers then used the Harvard T.H. Chan School of Public Health nutrient database to calculate the amount of gluten consumed.

Any deaths occurring throughout the study were examined through hospital records and autopsy reports.

As it was an observational study the researchers say no firm conclusions can be drawn about cause and effect.  

However, the researchers did conclude that their study results “do not support the promotion of a gluten restricted diet with a goal of reducing coronary heart disease risk”.