Zinc

Zinc is an essential trace mineral involved in the activity of hundreds of enzymes. It is needed for immune function, wound healing, protein and DNA synthesis, growth and development, and the senses of taste and smell. The body has no specialised zinc store, so a regular dietary supply is required. Zinc is commonly discussed alongside iron as a mineral to pay attention to on a vegan diet.

Recommended intakes

EFSA sets zinc reference values that rise with dietary phytate intake, reflecting the fact that phytate reduces zinc absorption.

Zinc and plant-based diets

Many plant foods are good sources of zinc, but zinc from plants is generally absorbed less efficiently than zinc from meat. The main reason is phytate (phytic acid), a compound found in whole grains, legumes, nuts and seeds that binds zinc in the gut. The NIH Office of Dietary Supplements notes that vegetarians may need as much as 50% more zinc than the RDA because of lower absorption, and the US Institute of Medicine made a similar observation when setting reference values.

Studies have found that vegetarians and vegans tend to have somewhat lower zinc intakes and blood zinc levels than non-vegetarians, although these are often within the normal range and clinical deficiency appears uncommon. The body can also adapt to lower intakes by absorbing a greater proportion of dietary zinc.

Vegan sources

Good plant sources of zinc include:

• Legumes – lentils, chickpeas, beans and peas;
• Soya foods – tofu, tempeh and edamame;
• Seeds – pumpkin seeds, hemp seeds, sesame seeds and tahini, chia seeds;
• Nuts – cashews, pine nuts, almonds and peanuts;
• Whole grains – oats, quinoa, wholemeal bread, brown rice;
• Fortified foods – some breakfast cereals;
• Others – nutritional yeast, mushrooms and wheat germ.

Improving absorption

Several food preparation methods reduce phytate levels and can increase the proportion of zinc absorbed:

1. Soaking dried beans, grains and seeds before cooking, and discarding the soaking water.
2. Sprouting (germinating) legumes, grains and seeds.
3. Fermenting, as in tempeh, miso and sourdough bread.
4. Leavening bread with yeast, which breaks down some phytate; leavened breads generally provide more absorbable zinc than unleavened breads or crackers.

Including protein-rich foods in a meal may also help zinc absorption. Organic acids, such as citric acid from fruit, may have a modest beneficial effect.

Signs of deficiency

Zinc deficiency can cause:

• poor growth in children;
• reduced appetite and changes in taste and smell;
• impaired immune function and slower wound healing;
• hair loss and skin problems;
• diarrhoea.

Groups at higher risk of low zinc status regardless of diet include pregnant and breastfeeding women, older adults, people with digestive disorders that affect absorption, and people who drink alcohol heavily.

Supplements

Most people on a varied vegan diet that includes legumes, whole grains, nuts and seeds can meet their zinc needs from food. Some vegan multivitamins include zinc. Long-term high-dose zinc supplementation can interfere with copper absorption and cause copper deficiency. The US tolerable upper intake level for adults is 40 mg per day from all sources, and the NHS advises not taking more than 25 mg a day of zinc supplements unless advised by a doctor.

Practical examples

Meals that combine several zinc-rich foods include:

• porridge made with oats, topped with pumpkin seeds and hemp seeds;
• hummus (chickpeas and tahini) with sourdough bread;
• a tofu and cashew stir-fry with brown rice;
• lentil and bean chilli served with quinoa.

This article is for general information. Individuals should consult a doctor or registered dietitian for personal advice.

See also

• iron
• protein
• meal planning
• vegan diet and health