The "greener" version of the Mediterranean diet, which includes more plant matter and much less red meat and poultry than the regular version, could be far more heart-healthy, particularly in men, according to a study published in the journal Heart on Monday.

In several trials, the Mediterranean diet has been related to a reduced risk of coronary heart disease, stroke, and diabetes. Its effect is believed to be linked to higher dietary intakes of fruit, vegetables, and whole grains and lower intakes of red meat.

Researchers decided to figure out if a green Mediterranean variant of this diet, higher in green plant food sources and much smaller consumption of red meat, could be even better for health.

294 sedentary and mildly obese individuals (BMI of 31) with an average age of 51 were randomly assigned to three dietary classes.

The first group obtained advice on improving physical exercise and basic guidance on achieving a balanced diet.

The second received the same physical activity recommendations plus calorie-restricted advice (1500-1800 kcal/day for men and 1200-1400 kcal/day for women) of the typical Mediterranean diet. It was low in simple carbohydrates, high in vegetables, and poultry and fish replacing red meat. It contained 28 g a day of walnuts.

The third group received guidelines on physical exercise and recommendations on the use of a similar calorie-restricted green variant of the Mediterranean diet ('green Med').

This contained 28 g/day walnuts, the prevention of red/processed meat, and higher concentrations of plant matter. It also contained 4 cups/day of green tea and 100 g of frozen cubes of Wolffia globosa (cultivated Mankai strain), a high protein type of aquatic plant duckweed, taken as a green plant-based protein shake as a partial replacement for animal protein.

After six months, the impact of each diet on weight loss and cardiovascular and metabolic risk factors was measured. Both forms of the Mediterranean diet lost more weight: green Med 6.2 kg; Mediterranean 5.4 kg; balanced diet 1.5 kg.

Waist circumference - a measure of potentially unhealthy midriff bulge - shrunk by an average of 8.6 cm for those on the green Med diet compared to 6.8 cm for those on the Mediterranean diet and 4.3 cm for those on a balanced diet.

The green Med diet group saw a bigger decrease in 'bad' low-density cholesterol of 6.1 mg/dl, a reduction of almost 4 percent. The comparable estimates were 2.3 mg/dl (nearly 1%) for those in the Mediterranean diet group and 0.2 mg/dl for those in the healthy diet group.

In the same way, other cardiovascular and metabolic risk factors increased further for those on the green Med diet, including diastolic blood pressure decreases, insulin tolerance, and a significant marker of inflammation, C-reactive protein, which plays a key role in artery hardening. The ratio of 'positive' to 'bad cholesterol has also improved.

"Our findings suggest that additional restriction of meat intake with a parallel increase in plant-based, protein-rich foods, may further benefit the cardiometabolic state and reduce cardiovascular risk, beyond the known beneficial effects of the traditional Mediterranean diet," concluded the team.