Mediterranean Diet + Nuts = Reversal of Metabolic Syndrome

An article published in 2008 by presents results of a scientific study in Spain that showed reduction in “metabolic syndrome” by the Mediterranean diet supplemented with nuts., Reuters, and others helped spread the news. The Bloomberg article was written by Nicole Ostrow.

Metabolic syndrome is a constellation of clinical factors that are associated with increased risk of type 2 diabetes and atherosclerotic complications such as heart attack and stroke. (Sometimes metabolic sydrome is called Syndrome X, which I sorta like. Oh, the mystery!) One in six Americans have the syndrome. Diagnosis requires at least three of the following five conditions:

  • High blood pressure (130/85 or higher, or using a high blood pressure medication)
  • Low HDL cholesterol: under 40 mg/dl in a man, under 50 in a women (or either sex taking a cholesterol-lowering drug)
  • Triglycerides over 150 mg/dl (or taking a cholesterol-lowering drug)
  • Abdominal fat: waist circumference 40 inches or greater in a man, 35 inches or greater in a woman
  • Fasting blood glucose over 100 mg/dl

The scientific study at hand is part of the PREDIMED study being conducted in Spain. For this portion of the study, 1,224 participants at high risk for cardiovascular disease were randomized to follow a 1) low-fat diet (considered the control group), 2) Mediterranean diet plus 1 liter virgin olive oil per week, or 3) Mediterranean diet plus 30 gm daily of mixed nuts.

Note that the nuts used in this study were walnuts, almonds, and hazelnuts. Half of all nuts were walnuts; a quarter of the nuts were almonds and a quarter were hazelnuts.

Participants were 55-80 years old, and 61% had metabolic syndrome at baseline. Participants could eat all they wanted, and there was no increase in physical activity for any of the groups. Participants were given instructions at baseline and quarterly.

After one year of intervention, the prevalence of metabolic syndrome was reduced by 14% in the Mediterranean diet plus nuts group compared to the control, low-fat diet group. The Mediterranean diet plus extra olive oil group reduced prevalence of metabolic syndrome by 7%, but this did not reach statistical significance (P=0.18).

New cases of metabolic syndrome continued to develop at about the same rate in all three groups. I.e., incident rates were not significantly different. So, the lower prevalence of metabolic syndrome after one year reflected reversion or clearing of the syndrome in many people who had it at baseline. Compared to the control group, people in the nutty group were 70% more likely to resolve their metabolic syndrome. Individuals in the oily group were 30% more likely than controls to resolve the condition.

(Feel free to consult a dictionary for definitions of “prevalence” and “incidence.”)

The researchers conclude that:

A traditional Mediterranean diet enriched with nuts could be a useful tool in the management of the metabolic syndrome.

My Comments:

Thirty grams (daily) of nuts is a decent-sized snack of about 180 calories. Thirty grams of almonds formed a heap in the palm of my hand, not touching my fingers. This is more than the “two tablespoons” reported by December 9.

If you have metabolic syndrome, you might want to try reversing it with all the usual methods (e.g., lose excess fat weight, exercise more) along with a traditional Mediterranean diet enriched with 30 gm of mixed nuts daily. As usual, check with your personal healthcare provider first. Be aware that many of them won’t know about this study.

The puzzling thing to me is: If the Mediterranean diet plus extra nuts is so effective in reversing metabolic syndrome, why didn’t that study cohort see fewer new cases of metabolic syndrome?

Steve Parker, M.D.

Additional reference: Salas-Salvado, Jordi, et al. Effect of a Mediterranean Diet Supplemented With Nuts on Metabolic Syndrome Status: One-Year Results of the PREDIMED Randomized Trial. Archives of Internal Medicine, 168 (2008): 2,449-2,458.

One response to “Mediterranean Diet + Nuts = Reversal of Metabolic Syndrome

  1. When you find an answer to your last question, be sure to post it. Meanwhile, it would seem to question the worth of the study.