A recent Toronto study suggests that diabetics can lower both their blood sugar and LDL (bad) cholesterol by replacing two ounces of carbohydrate in their daily diet with two ounces of mixed nuts.

Type 2 diabetics need to limit the amount of carbohydrates they eat. Often this means eating a diet with a slightly higher than average fat content, where the added fat replaces some carbohydrate. The researchers see substituting two ounces of mixed nuts for two ounces of carbohydrates as a simple dietary change that will help diabetics control their blood sugar and, as a bonus, also lower their LDL cholesterol.

The decrease in blood sugar seen in the study was about two-thirds the amount that the FDA would consider as clinically meaningful for a therapeutic agent — a new diabetes drug.

The study design was to have 117 type 2 diabetics supplement their usual daily diet with 75 grams (2.7 ounces) of either muffins, mixed nuts or half-portions of both, for three months. At the end of three months, their blood sugar was estimated from hemoglobin A1c measurement and their LDL cholesterol was also measured.

Based on the amounts the study participants actually ate, the researchers found that eating about two ounces of mixed nuts gave significant improvement in blood sugar and LDL cholesterol, compared to two ounces of muffins. The decrease in blood sugar seen in the study was about two-thirds the amount that the FDA would consider as clinically meaningful for a therapeutic agent — a new diabetes drug.

The nut supplement included almonds, pistachios, walnuts, pecans, hazelnuts, peanuts, cashews and macadamias.

How the nuts cause these metabolic changes isn't clear. Speculation centers on the fact that the fat in nuts is high in monounsaturated fatty acids (MUFAs). Other studies have seen similar health benefits from raising the amount of MUFAs in the daily diet, as long as they replace other types of fats and don't just add to total fat consumption.

Nuts are a high-calorie food, at 160-200 calories per ounce. Simply adding nuts to an existing diet would likely lead to weight gain. Substituting nuts for other food, particularly high-carbohydrate ones for diabetics, should keep weight stable.

The study was a joint venture between the University of Toronto Department of Nutritional Sciences and St. Michael's Hospital Risk Modification Centre.

An article on the study was published online ahead of print by Diabetes Care on June 29, 2011 and will also appear in a future print issue of the journal.