Zinc: how to get enough on a plant-based diet

By Lisa Simon and Isabelle Sadler

What is zinc?

Zinc is a mineral essential to cell division, playing a key role in growth during pregnancy and from birth through to adolescence. It is also important for the preconception period, as it plays a role in hormone balance and ovulation, and in men it is needed to regulate serum testosterone levels and make new sperm.

Zinc is also important for healthy immune function and is needed for wound healing, and the metabolism of proteins, fats and carbohydrates. Without zinc, we would not be able to taste, and it is critical for nerve development. Certain tissues and fluids in the body are dependent on good zinc intakes, as they contain relatively high concentrations. These include sperm and seminal fluid, the iris and retina of the eye, and the prostate.

Risks of deficiency

Symptoms of deficiency include poor growth, loss of appetite, impaired immune function, poor wound healing, taste changes, weight loss, and low testosterone levels in males. True zinc deficiency is rare, as the body increases absorption in the same way as it does with non-haem iron, when reserves are low. This means that body losses are reduced. However, it remains important to ensure adequate zinc intakes.

Recommended intake

In the UK, the recommended daily zinc intake for an adult woman is 7mg, and for adult men it’s 9.5mg.

Men’s requirements are higher because they lose zinc with each ejaculate and it is therefore important, particularly for men trying to conceive, to ensure adequate daily zinc intakes.

Dietary sources

There are many vegan zinc sources, including seeds (in particular poppy, sesame, chia and sunflower seeds), nuts (in particular almonds, cashew and pine nuts), beans, lentils, peanuts, soy foods such as tofu, tempeh and edamame beans, and the majority of grains. Dark chocolate also contains good amounts. In general, fruits and vegetables contain very little zinc.

Quorn™ (mycoprotein) is an excellent source of zinc, as a 100g serving provides 7.6mg zinc. The zinc content of some other foods are shown in the table below.

Food	Serving size	Zinc mg / serving
Quorn™ (mycoprotein)	100g	7.6
Cashew nuts	30g	1.7
Pecans	30g	1.6
All-bran type cereal	30g	1.5
Firm tofu, steamed or fried	75g	1.5
Wholemeal bread	80g (2 slices)	1.3
Tempeh	75g	1.4
Green/brown lentils, boiled	100g	1.4
Brazil nuts	30g	1.3
Peanut butter	40g	1.2
Red lentils	100g	1.0
Peanuts	30g	1.0
Tahini paste	19g	1.0
Chickpeas	100g	0.8

Note, this table is not an exhaustive list of food that contain zinc.

Top tips for getting enough zinc

• Include a variety of plant protein sources in your diet daily, such as different types of pulses (tofu, edamame, chickpeas, lentils etc.) and mycoprotein-based meat alternatives.
• Include a portion of nuts each day as a snack. A handful of cashew nuts (30g) provides 1.7mg zinc. The same size portion of almonds will give you 1mg, pecans 1.6mg, and peanuts 1.1mg. Make your own trail mix to provide some variety!
• Sprinkle seeds on whatever meals you can or blend them into soups and smoothies. One tbsp of hemp seeds gives you 1mg of zinc, and 1 tbsp of pumpkin seeds provides 0.7 mg. Use tahini paste in your salad dressings.

How to optimise zinc intake

While plant foods such as beans, nuts, and whole grains contain zinc, the bioavailability of zinc from these foods is relatively low compared to animal sourced foods. This is because these foods contain phytates, which bind with zinc making it harder to absorb the zinc from the food. Although refined grains contain less zinc overall, they also have lower levels of phytates, which can slightly improve zinc absorption.

There are several ways to reduce the phytate content of foods and enhance zinc bioavailability and absorption, mainly through food preparation methods. Common methods include:

• Fermentation: The fermentation process during the making of sourdough reduces phytates.
• Soaking grains and legumes overnight before cooking them can reduce phytate content. The cooking process can also reduce phytic acid content, cooking lentils for an hour can reduce phytic acid content by up to 80%.
• Sprouting seeds, grains, beans and legumes breaks down the phytates and makes zinc more available. Sprouting usually takes between 3-5 days, and no special equipment is needed, simply a jar and a lid with holes, or you can secure a cheesecloth around the top of the jar. There are many videos/blogs online showing how to sprout: don’t feel intimidated by sprouting, it really is very simple once you have the hang of it.

Another way of breaking down phytates is by adding foods containing acids, such as garlic. For example, by adding garlic to homemade hummus, the zinc absorption will be increased from the tahini and chickpeas.

Where possible, choose zinc fortified products such as fortified breakfast cereals.

Advice for zinc supplementation

It is always preferable to meet zinc needs through a varied plant-based diet, and to avoid supplements unless prescribed by a doctor to correct deficiency. However, low dose supplements are an option if you are struggling to meet your needs. The NHS advises that if you do take a supplement, this should be no more than 25mg a day unless advised to by a doctor.

Taking too much zinc can be harmful. This is because too much zinc reduces the amount of copper the body can absorb, which can contribute to anaemia and weakening of the bones.

Avoid taking iron and zinc supplements together. Studies have shown that iron has a negative effect on zinc absorption when taken together in the form of a supplement, whereas a meal containing both nutrients has not been shown to have the same effect.

 

Data on the nutrient content on food was taken from a BDA guide on alternative sources of zinc and the Food & Nutrition-NBRI database by the Quadram Institute.