Study reviews evidence on potential health risks associated with vegan diets

A growing number of people are adopting fully plant-based diets, but nutrition researchers are highlighting several potential health risks that can arise when meals are not carefully planned. A recent review summarised in a major health outlet has drawn attention to issues ranging from persistent fatigue to reduced bone strength, prompting renewed discussion about how vegans can safeguard long-term wellbeing.

Nutrients most often flagged in plant-based eating

Researchers point to a handful of nutrients that are harder to obtain from plants alone. Vitamin B12 is produced almost exclusively by microorganisms, so vegans who skip fortified foods or supplements are at particular risk of deficiency. Low B12 status has been linked in clinical literature to symptoms described as "brain fog," including poor concentration and slowed recall. Iron, zinc, calcium, iodine and the long-chain omega-3 fatty acid DHA are also commonly mentioned as nutrients to watch.

• Vitamin B12 — present mainly in fortified foods and supplements
• Iron and zinc — better absorbed from animal sources, though careful pairing with vitamin C can help
• Calcium, vitamin D and iodine — often lower in standard vegan menus
• Omega-3 (DHA/EPA) — typically requires algae-derived supplements

Bone health and other long-term concerns

Brittle bones and reduced bone mineral density have been reported in some long-term vegans, especially where calcium and vitamin D intake remains low and sun exposure is limited. Studies have also noted differences in fracture risk, though findings vary by population and diet quality. Separate research underlines why overall dietary patterns and lifestyle factors matter alongside any single nutrient. Cognitive symptoms, meanwhile, overlap with broader questions about how diet shapes brain ageing, as explored in work evaluating the MIND diet and dementia risk.

What experts recommend

Dietitians generally emphasise that well-planned vegan diets can meet most nutritional needs, but they advise regular blood tests, fortified staples and targeted supplementation. For those adapting their routine at different life stages, including new parents, evidence on chrononutrition strategies for postpartum weight management shows the value of timing meals to support metabolic health. With awareness and simple safeguards, the experts argue, many of the highlighted risks can be managed effectively.