RESEARCH UPDATE: New Mediterranean diet study investigates link between nut consumption and markers for Metabolic Syndrome
New fad diet plans hit the headlines each January, but the Mediterranean diet regularly clocks in as one of the top recommended diets every year. Almonds fit into the Mediterranean diet, which emphasizes plant foods including nuts, and a recent study shares results about the diet effects on Metabolic Syndrome and weight management. Metabolic Syndrome (MetS) and its cluster of markers - large waist circumference, elevated triglycerides, reduced HDL-cholesterol, elevated blood pressure and elevated blood glucose - have long been associated with increased cardiovascular risk.
The aim of a recent study from PREDIMED-Plus1 was to determine if changes in nut consumption over a 1-year period were associated with in differences in symptoms among middle-aged and older Spanish adults with high cardiovascular disease risk who followed a Mediterranean diet.
Data from 5,800 participants (3,005 men and 2,795 women, ages 55-75 years old) who completed a food questionnaire at the start of the study and at the 1-year mark was analysed. All participants were overweight or obese (BMI ≥ 27 and <40) and had MetS.
Nut consumption (including almonds) by study participants was validated by a food questionnaire and adherence to the Med Diet was confirmed in consultation with dietitians. From baseline to the 1-year mark, MetS symptoms were assessed, including waist circumference, HDL-cholesterol levels, triglyceride levels, fasting blood glucose, blood pressure (both systolic and diastolic), and excess body weight (both BMI and body weight).
The researchers then grouped the participants into three tertiles by determining increases in nut consumption during the study time period. After one year, average nut consumption amounts for tertile 1, tertile 2, and tertile 3 were as follows (P < 0.001):
- Tertile 1: 18.4 ± 14.4 g/day of nuts
- Tertile 2: 24.6 ± 11.2 g/day of nuts
- Tertile 3: 44.7 ± 18.9 g/day of nuts
After the 1-year follow-up, the groups with the largest nut consumption (tertiles 2 and 3) had consistent calorie intake compared to baseline, which suggests increased nut consumption did not have a significant impact on overall calorie intake. Researchers also found:
- When assessing MetS features and weight change, with each tertile of increasing nut intake, waist circumference, blood triglyceride concentrations, systolic blood pressure and BMI decreased significantly (P<0.05)
- Significant increases in extra virgin olive oil consumption and adherence to the Med Diet were observed across the 3 tertiles.
- When the three groups were compared to one another, the group that ate the most nuts (tertile 3) also increased consumption of extra virgin olive oil EVOO and improved adherence to the Mediterranean the most.
- For women, HDL-cholesterol levels increased with each tertile of increasing nut intake (P= 0.044)
- When comparing the group that ate the most nuts (tertile 3) to the group that ate the least nuts (tertile 1), participants in tertile 3 had greater decreases in waist circumference (men only), total body weight and BMI (P<0.05).
- There were no significant changes between groups in fasting blood glucose and diastolic blood pressure.
The researchers noted that these findings, except for the increase in HDL-cholesterol, were consistent with previous study findings. In the original landmark PREDIMED study, cardiovascular disease in those following the Med Diet was lowered by approximately 30% compared to those in the control diet.
Limitations of this study should be noted, and include:
- The study participants were older obese/overweight adults, presented with MetS and had a higher CVD risk, so the results may not be applicable to other populations.
- The food questionnaire may have caused overestimations of certain food groups, and the study design of recruiting attendance at the educational sessions may have limited inclusion of lower income participants.
- More research is needed to assess long-term results.
The findings suggest symptoms of MetS and excess weight were inversely associated with nut consumption. For this population of older adults with metabolic syndrome, boosting nut consumption and adhering to the Mediterranean diet were associated with reductions in body weight, BMI, waist circumference, triglyceride concentrations and systolic blood pressure. Increasing consumption of nuts, including almonds, may be an effective dietary strategy for managing weight and improving components of the metabolic syndrome. Click here to view the full study.
