The Safe and Effective Use of Plant-Based Diets with Guidelines for Health Professionals

Overview

This review summarises the evidence on plant-based diets, defined here as vegan and lacto-ovo-vegetarian diets. It closes with practical guidance for health professionals. The authors conclude that well-planned plant-based diets are safe and effective at every stage of life.

Health and environment

Plant-based diets use fewer natural resources and produce lower greenhouse gas emissions than diets based on animal products. Diets rich in whole grains, legumes, vegetables, fruit, nuts and seeds are associated with lower body weight, blood lipids, blood pressure and blood glucose. They are also linked to a lower risk of heart disease, type 2 diabetes, obesity and, modestly, cancer overall. Findings for individual cancers are less consistent. For bone health the picture is mixed: some studies show lower bone density and more fractures in vegans, often linked to low intakes of calcium, vitamin D and protein. High fibre and polyphenol intake supports a diverse gut microbiota that produces anti-inflammatory metabolites. Plant-based eating does not in itself raise the risk of eating disorders, although some people may use it to restrict food.

Nutrients to watch

The review discusses calcium, iron, zinc, iodine, vitamin B12, vitamin D, omega-3 fats and protein, with food sources, fortified products and supplements for each. Vitamin B12 must come from fortified foods or supplements, and vegans should have their status checked regularly. Vegetarians eating a varied diet are not at greater risk of iron or zinc deficiency. Algae-based omega-3 supplements are suggested, especially in pregnancy and breastfeeding.

Life stages

Guidance covers pregnancy and breastfeeding, infants, children and teenagers, older adults and athletes. In these groups needs are higher or intake may be limited, so careful planning and attention to key nutrients are especially important.

Guidance for health professionals

Clinicians should respect clients' food choices, including religious and cultural traditions. They should stay familiar with current research and vegetarian food preparation, and refer to dietitians when they lack expertise. The authors stress that the adequacy of a diet depends on the foods actually eaten, not on what the diet is called.