Metabolic syndrome could be reversed by following a Mediterranean diet with extra-virgin olive or nuts. This is according to a new study published in the Canadian Medical Association Journal.

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Researchers found that a Mediterranean diet supplemented with nuts or extra-virgin olive oil reversed metabolic syndrome in patients at high risk of cardiovascular disease.

Metabolic syndrome is defined as having three or more risk factors for cardiovascular disease or diabetes. Risk factors include abdominal obesity, high cholesterol, high blood pressure and high blood glucose levels.

It is estimated that around 34% of adults in the US have metabolic syndrome, most commonly caused by overweight and obesity, lack of physical activity and genetic factors.

For their study, researchers from Spain wanted to investigate the metabolic effects of a Mediterranean diet. "The Mediterranean diet is recognized as one of the healthiest dietary patterns," they note.

It involves high consumption of fruits, vegetables, whole grains, legumes and nuts, reducing intake of red meat, eating fish and poultry at least twice a week, and replacing butter with healthy fats - such as olive oil.

The Mediterranean diet has been associated with numerous health benefits. In 2013, Medical News Today reported on a study claiming the diet can reduce the risk of heart attack and stroke in high-risk patients, while a more recent study suggested that children who eat a Mediterranean diet are 15% less likely to be obese.

Mediterranean diets reduced abdominal obesity, blood glucose levels

The research team analyzed men and women aged 55-80 who were at high risk of cardiovascular disease. At study baseline, 64% of participants had metabolic syndrome.

All individuals were a part of the PREDIMED trial - an ongoing study that aims to assess the effects of a Mediterranean diet on cardiovascular diseases.

Participants were randomized to follow one of three diets: a low-fat diet, a Mediterranean diet supplemented with nuts or a Mediterranean diet supplemented with extra-virgin olive oil. They were followed-up for an average of 4.8 years.

Results of the study revealed that participants who followed the Mediterranean diet supplemented with nuts and the Mediterranean diet supplemented with extra-virgin olive oil saw a reduction in blood glucose levels and abdominal obesity. Furthermore, 28.2% of participants who followed the Mediterranean diets did not meet the criteria for metabolic syndrome by the end of the study.

The researchers point out, however, that neither of the Mediterranean diets were linked to lower incidence of metabolic syndrome.

Commenting on their findings, the researchers say:

"Mediterranean diets supplemented with olive oil or nuts were not associated with a reduced incidence of metabolic syndrome compared with a low-fat diet; however, both diets were associated with a significant rate of reversion of metabolic syndrome.

Such diets may be useful in reducing central obesity and hyperglycemia in patients with high risk of cardiovascular disease."

They add that there was no difference in weight loss or energy expenditure between groups, which indicates that the findings are down to changes in dietary patterns.

The researchers note that there are some limitations to their study. They point out, for example, that because study participants were older individuals at high risk of cardiovascular disease, their findings cannot be generalized to the entire population.

Earlier this year, a study reported by MNT suggested that the beneficial effects of a Mediterranean diet on blood pressure are down to the high levels of olive oil and green vegetables incorporated in the diet.

Our Knowledge Center article explains more about what the Mediterranean diet is and explores other associated health benefits.