Study debunks blood type diet

December 6, 2020 in Healthy Eating, Heart Health, Nutrition Topics in the News

Study debunks blood type diet

study by researchers with the Physicians Committee for Responsible Medicine, a non-profit of 12,000 doctors, found that blood type was not associated with the effects of a plant-based diet on body weight, body fat, blood cholesterol levels or blood sugar control.

This new study is based on a randomized controlled trial whose main findings were published last month in JAMA Network Open. The trial randomly assigned overweight participants with no history of diabetes to an intervention or control group for 16 weeks.

Related: Plant-based diet ramps up metabolism

Participants in the intervention group followed a low-fat, plant-based diet. The control group made no diet changes. The key finding was that a plant-based diet ramps up metabolism as measured by an increase in after-meal calorie burn of 18.7%, on average, for the intervention group over the control. 

To investigate a potential connection between blood type and diet, researchers conducted a secondary analysis among the plant-based diet group (intervention) of the 16-week randomized clinical trial. They considered whether the effects of a plant-based diet on body weight, blood lipids and blood sugar control are associated with ABO blood type.

Plant-based diet benefitted all blood types

The "blood type diet" recommends a mainly plant-based diet for people with blood type A, while it recommends a diet heavy in meat for those with blood type O. 

The study found that blood type made no difference. While the blood type diet says that a plant-based diet should be better for blood type A and less so for blood type O, it turned out to be beneficial for people of all blood types, and there was no evidence that meat-based diets are good for anyone.

The scientists measured body weight, fat mass, visceral fat (fat tucked around the organs), blood cholesterol and triglycerides, fasting blood sugar and hemoglobin A1c, a test result reflects your average blood sugar level for the past two to three months.

The researchers compared participants with blood type A to all other participants (non-A), and individuals with blood type O to all other participants (non-O).

There were no significant differences in any measure between individuals of blood type A and non-A, or between individuals of blood type O and non-O. The findings showed that all blood types benefitted equally from a vegan diet when looking specifically at weight loss and cardiometabolic health in overweight adults.

Source: Journal of the Academy of Nutrition and Dietetic, December 4, 2020.

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