Include at least 50 grams of almonds, cashews, chestnuts, walnuts or pistachios in your diet to control blood fats (triglycerides) and sugars - two of the five markers for metabolic syndrome.
A person is 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' and extra weight around the waist.
"Eating tree nuts is good for lowering risk for heart disease and other health problems such as diabetes and strokes," said John Sievenpiper, a physician at St Michael's Hospital in Toronto.
The study 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.
To reach this conclusion, Sievenpiper screened 2,000 articles published in peer-reviewed journals and found 49 randomised control trials with 2,000 participants.
Sievenpiper said the biggest reductions in triglycerides and blood glucose were seen when tree nuts replaced refined carbohydrates rather than saturated fats.
He said there was no adverse impact on the other risk factors for metabolic syndrome or weight gain, even though nuts are high in calories.
Nuts also have a high fat content but it is good or unsaturated fat.
"Fifty grams of nuts can be easily integrated into a diet as a snack or as a substitute for animal fats or refined carbohydrates," Sievenpiper noted in the paper published in the journal BMJ Open.