Eating walnuts may boost metabolism: Study

Regular consumption of walnuts may help reduce the potential prevalence rate of diabetes by improving metabolic syndrome risk factors, a study claims.

According to the study, published in the journal Nutrition Research and Practice, consuming walnuts may bring positive changes to metabolic syndrome status by increasing high-density lipoprotein (HDL) or "good" cholesterol and decreasing fasting glucose level.

Consuming walnuts daily could contribute to alleviating potential prevalence rate of diabetes by favourably changing hemoglobin A1c (HbA1c) and circulating adiponectin levels.

HbA1c is the average blood glucose (sugar) levels for the last two to three months.

This study was conducted in the form of controlled crossover trial after randomly dividing 119 of Korean male and female adults (aged 30 to 55 years) with metabolic syndrome into two groups.

Subjects in the first group were instructed to consume 45 grammes of walnuts, and the second group received iso-caloric white bread per day for 16 weeks as snack.

After 16 weeks of clinical trials, both groups had a six-week rest period, having a general meal.

After the rest period, white bread and walnut were cross overly distributed to the first group and the second group, respectively, for 16 weeks intake.

In addition to this, lipid profile, HbA1c, adiponectin, leptin, and apolipoprotein B, as well as anthropometric and bioimpedance data were measured four times throughout the study.

"This is a very accurate study due to its sophisticated design, such as random group designation and crossover trial with washout (general meal) period inserted," said Hyun-Jin Park, lead investigator of ICAN Nutrition Education and Research.

"The study focuses on analysing the effect of walnut consumption on various indicators of metabolic syndrome, including fasting glucose level, blood lipids, blood pressure, adiponectin and leptin level in the blood," Park added.

According to the study, the improvement rate for the five diagnostic factors of metabolic syndrome, blood pressure, blood sugar, cholesterol levels, abdominal fat and triglycerides, is revealed to be 28.6 per cent to 52.8 per cent.

Moreover, 51.2 per cent of participants with metabolic syndrome at baseline reverted to a normal status after the 16 weeks of walnut consumption, researchers said.

In particular, the level of high-density lipoprotein cholesterol (HDL-C), fasting glucose, HbA1c, and adiponectin improved significantly, researchers said.

"As this clinical trial has shown, walnut consumption has a positive effect on the improvement of the metabolic syndrome," said Park.

"Therefore, taking walnuts as snacks, instead of high-carbohydrate snacks, may be a good choice for the prevention and improvement of metabolic syndrome," she added.