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Throwdown, round 1: plant vs animal protein for metabolic syndrome

The DASH diet is frequently tested in clinical trials, and often performs well. But the diet’s formulation includes strong limitations on red meat, which may be based on outdated evidence. This study compared animal-protein rich diets with a typical DASH diet.

Study under review: Type and amount of dietary protein in the treatment of metabolic syndrome: a randomized controlled trial


Metabolic syndrome is a cluster of risk factors that greatly increases[1] the risk of dying from any cause (1.5-fold) and especially cardiovascular disease (CVD) specific causes (2.4-fold). This condition is diagnosed as either having or being on medications to treat at least three of the five following criteria:

  • Abdominal obesity (waist circumference greater than 40 inches (men) or 35 inches (women)),

  • Elevated fasting blood glucose (more than 110 mg/dL),

  • Elevated fasting triglycerides (more than 150 mg/dL),

  • Low HDL-c (less than 40 (men) or 50 (women) mg/dL), and

  • Hypertension (systolic blood pressure higher than 130 mmHg and/or diastolic blood pressure higher than 85 mmHg).

Reducing these risk factors for CVD is the primary goal of managing metabolic syndrome, which is often done through lifestyle modification. Notably, changes to diet and exercise that facilitate a 5-10% weight loss can address and significantly improve each risk factor. While a variety of dietary approaches can result in weight loss in overweight and obese adults, as explored[2] in Study Deep Dives Issue #6 (April, 2015), some dietary approaches may benefit people with metabolic syndrome more than other approaches.

One currently accepted dietary pattern to reduce CVD risk factors is the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in vegetables, fruit, low-fat dairy products, whole grains, poultry, fish, and nuts. The diet is low in sweets, sugar-sweetened beverages, and red meats. The DASH diet is designed to be low in saturated fat, total fat, and cholesterol, and rich in fiber, potassium, magnesium, and calcium.

In the OmniHeart (Optimal Macronutrient Intake Trial for Heart Health) trial, two variations of the DASH dietary pattern were compared with DASH. One variation replaced 10% of total daily energy from carbohydrate with protein, and the other replaced the same amount of carbohydrate with unsaturated fat. Both variations led to greater reductions of estimated CVD risk than the standard DASH diet. Notably, all three tested diets had a roughly even split between animal- and plant-based protein.

This study sought to expand upon the findings of the OmniHeart trial by comparing the effects of three variations of the DASH diet, which differed in protein type (plant vs. animal) and amount (18% vs. 27%), on metabolic syndrome criteria.

Metabolic syndrome is a cluster of risk factors that greatly increases the risk of cardiovascular diseases, the treatment of which includes diet and exercise to facilitate weight loss. The DASH diet is considered a prudent dietary pattern to address these risk factors, but other research has shown variations of the diet to be more efficient. The study under review was designed to determine how protein type (plant vs. animal) and amount (18% vs. 27%) affected metabolic syndrome criteria.

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Other Articles in Issue #12 (October 2015)

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