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The Prediabetes Nutritionist

Swapping Starchy Carbs for Quinoa May Reduce Blood Sugar Spikes after Meals in Prediabetes

Swapping starchy carbohydrates, including grains, beans, tubers, and their by-products, for quinoa-based products may reduce post-meal blood sugar spikes in older adults with prediabetes, a recent study has found.

“We compared the blood sugar patterns and found that when participants had eaten quinoa, their blood sugar spike was lower than with their usual diet. This is crucial because post-meal blood sugar spikes are a determining factor in the progression of type 2 diabetes,” Diana Diaz Rizzolo, PhD,  member of the Faculty of Health Sciences at the Universitat Oberta de Catalunya (UOC) and researcher at the August Pi I Sunyer Biomedical Research Institute (IDIBAPS) said in a press release.

The study, “Glycaemia fluctuations improvements in old-age prediabetic subjects consuming a quinoa-based diet: a pilot study,” was published in Nutrients.

Quinoa, a grain-like carbohydrate, is a good source of quality proteins, unsaturated fatty acids, vitamins and minerals. It is rich in fibre and contains slow-digesting carbohydrates making it a low glycaemic index cereal. Recent studies suggest that quinoa contains blood sugar-lowering antioxidant compounds such as polyphenols, but very few studies have investigated the effects of a quinoa-enriched diet on blood sugar levels in people with prediabetes.

“Seventy per cent of people with prediabetes will go on to develop the disease. This conversion rate is even higher among older adults, which means that prediabetes plus ageing equals a tremendous increase in the risk of developing the disease. This is why we wanted to see whether quinoa could be used to prevent the onset of the disease in this group”, Dr Rizzolo said.

Nine participants (six female) with a mean age of 69 years participated in the study. They ate their usual diet for four weeks and then swapped to a quinoa-based one – where they replaced all grains, flour, tubes, legumes, and all flour products made from them, such as brioche and biscuits with quinoa or quinoa-based products – for the following four weeks. All quinoa and quinoa-based products were manufactured by a food company and delivered to the participants.

The participants wore blood glucose monitors throughout the study, and at two-weekly intervals, the researchers collected their blood glucose readings. Their weight, blood pressure, lipid profile, fasting blood glucose and physical activity levels were monitored every two weeks once they started consuming the quinoa-based diet.

Although they ate the same number of calories during both diet periods, the participants ate fewer carbohydrates and more fat during the quinoa diet phase. This difference in nutrient profile may have significantly affected their blood glucose levels.

“We observed a lower consumption of carbohydrates, polysaccharides and starch, and a higher consumption of fats due to the products delivered because quinoa contains fewer carbohydrates and more fats….the presence of fibre, protein or fat can decrease…postprandial blood glucose peak and quinoa is a food that not only has fewer carbohydrates but also has significant amounts of fibre, protein and healthy fats,” the researchers wrote.

After the quinoa diet, the participants lost an average of 1.6kg and reduced their weight circumference by 1.5cm. Remarkably, their glycated haemoglobin (HbA1c) – the average blood glucose over two to three months – decreased by 1% throughout the study. However, although their fasting blood glucose decreased during the first four weeks when they consumed their regular diet, it remained stable during the quinoa diet phase

The researchers note that quinoa’s effect on blood glucose may be due to its unique nutrient composition.

“With more precise analysis, we observed that other nutritional variables played an important role in modulating glucose fluctuations in our subjects… we observe that the nutrients that promote the decrease in glycaemia are those that are present in quinoa: cis FA [fatty acids], PUFAw6 [omega-6 polyunsaturated fatty acids], cellulose and phytic acid. On the contrary, nutrients that promote and increase glucose with the greatest significance are those not highly present in quinoa, but rather in other foods, and these are soluble fibre and gamma-tocopherol,” they wrote.

Overall, “a diet rich in quinoa reduces postprandial glycemia [high blood glucose] despite interpersonal differences, thanks to the joint action of different nutrients and the suppression of others consumed in a regular diet, which could apply a brake to the progression to T2D [type 2 diabetes],” the researchers wrote.

The scientists highlighted two limitations of the study: its small size and short duration.

“We conclude that in old age and high T2D-risk population, a diet rich in quinoa reduces postprandial glycaemia and could be a promising T2D-preventive strategy,” they wrote

The Take-home Message

Quinoa is a highly nutritious grain-like cereal. It is one of a few plant sources of quality plant proteins, and with its balanced carbohydrate and fat content is considered a slow-digesting carbohydrate.  This small study has found that replacing most carbohydrates in an older person’s diet with quinoa and products made from it results in weight and body fat loss and HbA1c reduction. It may not be practical or necessary to replace all carbohydrates in your diet with quinoa to derive similar benefits. However, adding more quinoa to your diet could be beneficial.

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