The paper found that there was 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.
Dr. John Sievenpiper, a physician and researcher in the Clinical Nutrition and Risk Factor Modification Centre of St. Michael's Hospital said that according to him this was the first systematic review and meta-analysis examining all of the collective evidence of randomized clinical trials on the effect of tree nuts on metabolic syndrome.
He further added that the biggest reductions in triglycerides and blood glucose were seen when tree nuts replaced refined carbohydrates rather than saturated fats and there was no adverse impact on the other risk factors for metabolic syndrome or weight gain, even though nuts are high in calories, however they also have a high fat content, but it's good, or unsaturated, fat.
A person would be considered to have metabolic syndrome if he or she has three of the following risk factors; low levels of "good" cholesterol; high triglycerides; high blood pressure; high blood sugar; extra weight around the waist.
The U.S. Food and Drug Administration has granted tree nuts a qualified health claim for cardiovascular disease risk reduction. Tree nuts are also recommended as part of the Mediterranean, Portfolio and DASH (Dietary Approaches to Stop Hypertension) diets for cardiovascular disease prevention and management based on their ability to reduce bad cholesterol.
The study is published in the journal BMJ Open.