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New studies indicate benefits of eating tree nuts

Toronto, July 30, 2014

By Leslie Shepherd

Dr. John Sievenpiper
Dr. John Sievenpiper

Eating tree nuts appears to help lower and stabilize blood sugar levels in people with Type 2 diabetes compared to those on a control diet, according to a study published in the online journal PLOS ONE today.

Eating tree nuts also appears to help reduce two of the five markers for metabolic syndrome, a group of factors that raise the risk for heart disease and other health problems such as diabetes and strokes, says a separate study published yesterday in the journal BMJ Open.

Both studies were conducted by Dr. John Sievenpiper, a physician and researcher in the Clinical Nutrition and Risk Factor Modification Centre of St. Michael’s Hospital.

The PLOS ONE paper, a systematic review meta-analysis of the totality of the evidence from 12 clinical trials in 450 participants, found that eating about two servings a day of tree nuts improved the two key markers of blood sugar: the HbA1c test, which measures blood sugar levels over three months, and the fasting glucose test, where patients are not allowed to eat or drink anything but water for eight hours before their blood glucose levels are tested.

The BMJ Open paper found that eating tree nuts appears to help reduce two of the five markers for metabolic syndrome, a group of factors that raise the risk for heart disease and other health problems such as diabetes and strokes. The paper found a “modest decrease” in blood fats known as triglycerides and blood sugars among people who added tree nuts to their diets compared to those who ate a control diet.

Tree nuts are such things as almonds, Brazil nuts, cashews, chestnuts, coconuts, hazelnuts, pecans, macadamia nuts, walnuts, pine nuts and pistachios. They do not include peanuts, which are legumes.

In both papers, the best results were seen when tree nuts replaced refined carbohydrates rather than saturated fats. Participants in the randomized control trials ate between 50 and 56 grams of tree nuts a day. One serving of tree nuts is about ¼ cup or 30 grams. Dr. Sievenpiper said that people in North America consume on average less than one serving a day, so this is one way they can adapt their diets to take advantage of the metabolic benefits.

Dr. Sievenpiper said that while nuts are high in fat, it’s healthy unsaturated fat and while they can also be high in calories, participants in the clinical trials did not gain weight.

Both studies received funding from the International Tree Nut Council Nutrition Research and Education Foundation and Canadian Institutes of Health Research.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

Media contacts

For more information, or to arrange an interview with Dr. Sievenpiper, contact:

Leslie Shepherd
Manager, Media Strategy
416-864-6094
shepherdl@smh.ca