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15-08-2011 | Cardiometabolic | Article

Nut consumption may improve glycemic control in diabetes

Abstract

Free abstract

MedWire News: Patients with Type 2 diabetes who consume 75 g of mixed nuts every day as a replacement for an energy-equivalent amount of carbohydrate show improved glycemic control and lipid profile, study results show.

"We believe that, with the appropriate advice, nut intake at these levels can be achieved and maintained," David Jenkins (University of Toronto, Ontario, Canada) and colleagues comment.

Recently, concerns have emerged over the impact of refined carbohydrate foods in increasing postprandial glycemia and reducing high-density lipoprotein (HDL) cholesterol.

Replacement of carbohydrate by "healthy" fat, such as monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs), has been increasingly recognized as a possible therapeutic strategy in the treatment of diabetes.

Furthermore, increased proportions of fat and protein in the diet, especially of plant origin, may confer metabolic benefits and reduce the risk for developing coronary heart disease (CHD) and diabetes.

"However, there is little guidance on the optimal foods with which to increase the fat and protein intakes, and fear persists that increasing the proportion of fat in the diet will increase body weight," Jenkins and team comment in the journal Diabetes Care.

Noting that few studies have addressed these concerns, the researchers initiated a study addressing the effect of mixed nut consumption as a source of vegetable fat.

They randomly assigned 117 Type 2 diabetic subjects to eat either mixed nuts (75 g/day), muffins, or half portions of both, with each of the three regimens providing 475 kcal (as part of a 2000-kcal total daily energy consumption).

The nuts were a mixture of unsalted and mostly raw almonds, pistachios, walnuts, pecans, hazelnuts, peanuts, cashews, and macadamias. The muffin was a wholewheat product sweetened with apple concentrate, with no added sugar, and had a similar protein content to the nuts, by the inclusion of egg white and skim milk powder.

Over the 3-month study period, Jenkins et al found that the full-nut dose reduced glycated hemoglobin (HbA1c) over the study period by 0.21%; by contrast there was no change in HbA1cc with the half-nut dose or muffin.

Low-density lipoprotein (LDL) cholesterol also decreased significantly after the full-nut dose compared with muffin. The LDL cholesterol reduction after half-nut dose was intermediate and not significantly different from the other regimens.

Jenkins et al note that for the full-nut dose the resulting relative increase in MUFA intake was modest, at 8.7% of total calories.

"There is a requirement for pharmacological interventions aimed at improving glycemic control to demonstrate that they have no negative impact on CHD. In this respect, nut consumption not only improved glycemic control but also lipid risk factors for CHD," the researchers conclude.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Andrew Czyzewski

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