Does a plant-based diet need to be very low in fat, or do nuts, seeds and avocados belong in it?

Brenda DavisRD · registered dietitian, plant-based nutrition

Whole-food fats belong, at about an ounce of nuts and an ounce of seeds a day, with total fat at 15 to 25 percent of calories and added oils minimised.

What it rests onNuts and seeds carry essential fats, vitamin E, folate and trace minerals, have the lowest glycaemic load of any whole plant food, and their consumption is associated with reduced heart disease, stroke, hypertension, type 2 diabetes, metabolic syndrome and dementia, with maximum benefit at about an ounce or two a day. She accepts the very-low-fat evidence for severe coronary artery disease and rejects its generalisation.

Dean Michael OrnishMD · internal medicine and cardiovascular disease; founder and president, Preventive Medicine Research Institute

Hold total fat to about 10 percent of calories on a whole-foods vegetarian diet.

What it rests onThe published reversal protocol: intensive lifestyle changes comprising a 10% fat whole foods vegetarian diet, aerobic exercise, stress management training, smoking cessation and group psychosocial support, in 48 patients with moderate to severe coronary heart disease, with more regression of coronary atherosclerosis at five years than at one.