Zinc

Zinc is an essential trace element that has several important functions; it helps to make new cells and enzymes, helps us process carbohydrate, fat and protein in food, strengthens the immune system and can help with the healing of wounds. Zinc may inhibit the replication of the rhinovirus; the most frequent cause of common cold symptoms. A 2011 Cochrane review suggests that taking zinc supplements within a day of the symptoms starting can speed up recovery and lessen the severity of a cold (Singh and Das, 2011).

The RNI for zinc is 7mg per day for women and 9.5mg per day for men (Department of Health, 1991). Like iron, the bioavailability of zinc may be reduced if there is a high presence of absorption inhibitors such as phytate and polyphenols. However, you can limit the effect of these as described above; soaking and sprouting pulses, grains and seeds, and fermenting grain products (using bread rather than crackers). As stated for iron, although zinc may be absorbed at a lower rate from wholegrain bread than white bread (due to the phytates), but the higher amount of zinc in wholegrain bread more than compensates for the lower absorption. 

It has been suggested that vegans with high intakes of unrefined grains might need slightly more zinc than recommended (Gibson et al., 2014). However, you shouldn’t take more than 25mg of zinc supplements a day, unless advised to by a doctor. Taking high doses can lead to a copper deficiency, anaemia and weakening of the bones.

In a large EPIC study of meat-eaters, fish-eaters, vegetarians and vegans, average zinc intakes among women were above the RNI of 7mg in all dietary groups. Among the men, the average intake of all groups except the meat-eaters was slightly below the RNI of 9.5mg per day, but the meat-eaters’ intake was only just above it at 9.78mg day (Davey et al., 2003).

These results concur with those of the earlier NDNS from 2008/2009 and 2011/2012 which found that the average daily intake of zinc from food was close to or above the RNI for most people. Boys aged 11-18 years were slightly under at 90 per cent of the RNI and girls that age a bit lower still at 81 per cent of the RNI (Bates et al., 2014). A number of people (nine per cent of 4-10 year olds, 17 per cent of 11-17 year olds and 10 per cent of men over 65) had zinc intakes below the LRNI. 

Other studies from industrialised countries show that for vegetarians, up to the age of 11, zinc intakes are similar or even higher than those of meat-eaters. This may reflect plant-based foods being the major source for iron and zinc during childhood, irrespective of dietary practices (Gibson et al., 2014). 

Food (medium portions) Zinc (mg)
RNI: 7mg/day for women and 9.5mg/day for men
Pumpkin seeds (1 handful/35g) 2.7
Lamb chop, grilled (edible portion 70g) 2.5
Tofu, fried (100g) 2.0
Bacon, grilled (46g) 1.2
Brown rice, boiled (180g) 1.2
Red lentils, boiled (120g) 1.2
Cashew nuts (20 nuts ~ 20g) 1.1
Chicken breast, grilled (130g) 1.0
Bran flakes (30g) 0.8
Baked beans (135g) 0.7
Wholemeal Spaghetti, boiled (220g) 0.7
Wholemeal bread (36g) 0.6
Sesame seeds (1 tbsp/12g) 0.6
Kidney beans, canned (90g) 0.6
Spinach, boiled (90g) 0.5
Figs (three dried fruits 60g) 0.4
Broccoli, boiled (85g) 0.3
Prunes (six dried fruits 48g) 0.2
Curly kale, boiled (95g) 0.2

Table 6.0 The zinc content of selected foods.

Source: FSA, 2002.

Table 6.0 shows the shows the zinc content of medium-sized portions of selected foods including different types of meat, fruit, vegetables, pulses, nuts and wholegrain foods. The concentration of zinc in plants varies based on levels of the element in soil. When there is adequate zinc in the soil, the food plants that contain the most zinc are wheat (germ and bran) and various seeds (pumpkin, sunflower and sesame). 

While red meat undoubtedly provides a source of zinc, it also contains high levels of unhealthy saturated fat, cholesterol and growth hormones. Furthermore, animal protein (but generally not plant protein) raises levels of IGF-1, a growth hormone linked to several cancers. Red and processed meats are also linked to several cancers including bowel, prostate and pancreatic cancer (WHO/IARC, 2015). You are better off getting your zinc from plant-based sources such as wholegrain foods, nuts and seeds which contain healthy essential fatty acids and valuable fibre. 

A daily intake of 10mg could be achieved from wholegrain cereal and soya milk, beans or hummus on wholemeal toast, tofu or tempeh stir-fry with cashews, broccoli and pumpkin seeds and brown rice. Additional snacks of dried fruit, nuts and seeds would provide a substantial boost.