Plant-based eating has been studied for several health conditions. Evidence varies by outcome and by the foods included; these are some of the better-studied areas.
Heart disease
Small trials of intensive lifestyle programmes, combining a low-fat vegetarian diet with exercise, stress management and smoking cessation, found some regression of coronary narrowing. Plant-rich diets can support heart health alongside medical care.
Type 2 diabetes
Vegetarian and vegan diets can improve blood sugar control in adults with type 2 diabetes. Trials support benefits for HbA1c and body weight; medication changes should be supervised by a clinician.
High blood pressure
Some plant-rich eating patterns lower blood pressure in clinical trials, though results vary and evidence for vegan diets alone is less certain. Limiting sodium and eating potassium-rich foods can help; treatment needs remain individual.
Certain cancers
The World Health Organization classifies processed meat as a Group 1 carcinogen (the same evidence category as tobacco, not the same size of risk). Wholegrains and dietary fibre have strong evidence for reducing colorectal cancer risk.
A well-planned plant-based diet can be nutritionally adequate. These five nutrients deserve attention, along with iodine, selenium and zinc. Use fortified foods and appropriate supplements where needed.
Vitamin B12
Use a reliable B12 supplement or sufficient fortified foods. B12 is made by microorganisms and occurs naturally in animal foods. Follow an appropriate dose schedule; weekly tablets need a different dose from daily ones.
Omega-3 (ALA → EPA/DHA)
Ground flax, chia and hemp provide ALA; the amount matters. Conversion to EPA and DHA is limited. An algae-based EPA/DHA supplement supplies these directly, without fish.
Iron
Lentils, beans, tofu, pumpkin seeds, dark greens and fortified grains all carry iron. Pair them with something containing vitamin C (citrus, peppers, tomatoes) and absorption jumps significantly.
Calcium
Fortified plant milks, tofu set with calcium, tahini, kale, bok choy, dried figs. Easy to hit daily targets once you know which foods carry it.
Vitamin D
Same advice as for everyone: if you don't get regular sunlight, supplement. This is a population-wide issue, not a vegan one.
Who actually says this
Professional guidance, in their own words.
These professional bodies provide guidance on planning vegetarian and vegan diets. Their statements differ in scope, including the ages and life stages covered.
"It is the position of the Academy of Nutrition and Dietetics that, in adults, appropriately planned vegetarian and vegan dietary patterns can be nutritionally adequate and can offer long-term health benefits such as improving several health outcomes associated with cardiometabolic diseases."
"Plant-based diets can support healthy living at every age and life stage. But as with any diet, you should plan your plant-based eating to meet your nutritional needs."
"With good planning, a vegetarian diet can be a healthy choice that meets your growing child’s nutritional needs."
食事が皮膚の健康に与える影響に関する研究は、心臓や代謝に関する証拠よりも初期段階ですが、その方向性は一貫しています。高GI食や乳製品に富んだ食事は、複数の観察研究においてニキビのリスク上昇と関連しているように見えます。これはおそらくホルモン経路を介したもので、乳製品には天然の成長ホルモンが含まれており、加工食品からのグリセミック指数スパイクはIGF-1を上昇させます。American Journal of Clinical Nutritionに2007年に発表されたランダム化比較試験では、低GI食を摂った参加者において著しいニキビの減少が確認されました。
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