A new study published in the Journal of the American Medical Association (JAMA), which concluded that people without diabetes or cardiovascular disease don’t need to worry about where a food falls on the glycaemic index (GI) – even if they’re overweight or obese, has met with a mixed response, with Behind The Headlines – Health News from NHS Choices, saying that the GI diet certainly hasn’t been “debunked” for “most healthy people”.

The study was published in JAMA, December 17, 2014, by Dr Frank M Sacks (Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston) et al, ‘Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity’.

The study found that a healthy diet modified to have a low glycaemic index did not improve insulin sensitivity, lipid levels or blood pressure in overweight and obese adults, compared with a diet that contained a high glycaemic index, according to a randomised 5-week controlled feeding study.

“In the context of an overall Dietary Approaches to Stop Hypertension (DASH) type of diet, using glycaemic index to select specific foods may not improve cardiovascular risk factors or insulin resistance, the study authors concluded.

Dr Sacks added that people who want a good overall diet should look toward Mediterranean-style diets or the DASH diet, which emphasizes vegetables, fruits, fat-free dairy, whole grains, fish, poultry, nuts and vegetable oils.

However, a review of clinical effectiveness of research in PubMed Health, a service provided by the National Center for Biotechnology Information at the U.S. National Library of Medicine, by Behind The Headlines – Health News from NHS Choices, said on December 19 that the GI diet ‘debunked’ claims are misleading, referring to the study that was republished in the Daily Mail Online.

Today, the Mail Online says, “The GI diet debunked: Glycaemic index is irrelevant for most healthy people”, explaining how “it doesn’t matter if you eat white or wholewheat bread”. This is overgeneralised and misleading, so the diet certainly hasn’t been “debunked”, Health News from NHS Choices, said.

“Glycaemic index (GI) measures how quickly foods containing carbohydrates raise blood sugar levels in the bloodstream. It’s used in some diets on the basis that foods that raise blood sugar slowly (low-GI) are considered better for you.”

This small US study tried mainly obese people on different high- and low-carbohydrate versions of the GI diet for five weeks at a time. It found that low-GI diets were no better than high-GI diets at reducing certain risk factors for cardiovascular disease and diabetes.

However, the results came from mainly obese adults, a quarter of whom had high blood pressure – so may not necessarily represent “most healthy people”. The very select group involved in this research makes it difficult to generalise the findings to the wider population.

The study concluded that for this group of overweight people, the evidence of the GI diet reducing certain risk factors for cardiovascular disease and diabetes is lacking. However, the diet certainly hasn’t been ‘debunked’ for “most healthy people”, as the Mail Online claimed, Health News from NHS Choices, said.