Zinc deficiency: here are the best sources of zinc

What do reproduction, wound healing, muscle building, great eyesight and hair growth have in common? They all need the mineral zinc to function properly! No mineral has such a more powerful influence on the immune system, skin and hair than zinc. However, up to 50 per cent of the world’s population does not consume enough of it. 

Without zinc, hours of exercise in the gym would be a total waste of time, sperm production would be negatively affected and you would not grow any hair. But fortunately, zinc is present in every cell of your body – even in cases of a zinc deficiency.

Find out about great sources of zinc, causes of zinc deficiency, zinc deficiency symptoms and how to treat a deficiency in this essential mineral. Excess zinc levels are also dangerous to the body – we explain why this is the case in our article. 

What does zinc do?

Zinc is indispensable for good health – it carries out tasks in every body cell. Since your body cannot produce the essential trace element itself, you have to consume it daily through food. The body contains a total of two to three grammes of zinc. At 1.5 milligrammes, your muscles store the largest proportion of it.^[1]

Did you know that, on average, a person loses three to four milligrammes of zinc daily via stool and urine? This is how the intestines and kidneys prevent a zinc surplus in your body.^{[1, 2]}

What is the function of zinc in the body?

As a coenzyme (auxiliary molecule) zinc is an all-rounder. Zinc allows hair to grow and wounds to heal. After eating, it helps the pancreas produce insulin, which lowers blood sugar. Zinc also stimulates the production of testosterone and activates certain proteins to build muscle. If body cells are damaged, zinc promotes cell division to create new cells. Zinc helps boost our immune system and is therefore especially important in the first few years of our life.^{[2, 3]}

Together with the mineral selenium, zinc binds heavy metals such as lead, which accumulate in your body. The mineral and heavy metal form an insoluble complex in which the heavy metals lose their toxic effect. This way, minerals protect your body, especially the nerve cells, from damage caused by heavy metals.^[3]

Did you know that if there were no zinc in your body, you would not be able to produce the enzyme alcohol dehydrogenase? This enzyme breaks down alcohol. Without alcohol dehydrogenase, every glass of wine consumed would lead to alcohol poisoning.^[4]

Is zinc good for your senses?

One of the zinc deficiency symptoms is a weakened sense of smell. Some researchers suspect that zinc plays a role in it. Our vision is also strongly dependent on zinc: the trace element supports the transportation of vitamin A from the liver to the retina of the eye. Without vitamin A, our eyes could not perceive light; in other words, we would not be able to see.^{[6, 7]}

How much zinc do I need?

According to the NHS, men should consume 9.5 milligrammes of zinc a day, while women should only consume seven milligrammes. During pregnancy, a woman’s daily requirement increases to ten milligrammes, as the mother needs to supply her unborn child with zinc and loses large quantities due to strong urges to urinate. Breastfeeding mothers have a higher requirement of eleven milligrammes, since they feed zinc to their child via breast milk.^[8]

The American National Institutes of Health recommends a similar, only slightly higher zinc intake – eight milligrammes per day for adult women and eleven milligrammes for men and pregnant women.^[9]

Foods with zinc: how can I get zinc naturally?

Both animal and plant-based foods are great sources of zinc. However, animal products contain significantly more zinc on average. At the same time, your body can absorb zinc from animal foods much better than from plant-based foods.^[10]

Foods with zinc	Amount of zinc in mg per 100 g
Oysters, wheat germ, wheat bran	10–25 mg
Edam, Swiss Emmental, eggs, pork liver, beef, sunflower seeds, linseed, soy flour, cocoa powder	5–10 mg
Gouda, Parmesan, rye, wheat, barley, millet, oats, quinoa, peas, lentils, beans, brazil nuts, peanuts, walnuts, chia seeds, dark chocolate	2.5–5 mg

Both sweet and regular potatoes contain approximately one milligramme of zinc, and other vegetables such as green beans and kale contain zinc too. Vegans can also opt for fortified vegan foods (such as cereal) or zinc-rich foods such as chickpeas, legumes, nuts and tofu.

Your small intestine cannot absorb 100 per cent of the zinc from foods. It absorbs 40 per cent from meat, milk and cheese, while the absorption rate for vegetables and the link is 20 per cent.^[11]

What are typical causes of zinc deficiency?

Zinc deficiency can be associated with various health problems and risks. Children especially need to be supplied with sufficient amounts of the mineral, as this particular mineral deficiency leads to diarrhoea and pneumonia – the most frequent causes of death among children under the age of five worldwide.^[12–15]

Interestingly, climate change could have a negative impact on our zinc levels. Due to high carbon dioxide emissions, the number of truly zinc-rich foods – that is, foods with a high zinc content – is said to have declined significantly. Plant-based and animal foods imported from South East Asia or South Africa also contain lower amounts of zinc because the soil there is lower in zinc.

Causes of zinc deficiency: when does zinc deficiency happen?

If you sweat a lot – be it through exercise or in hot weather – you will lose a lot of zinc by sweating. You should compensate for these losses with a balanced diet filled with zinc-rich foods. A vegetarian or vegan diet can also turn into causes of a zinc deficiency, as the small intestine absorbs less zinc from plant-based foods. If you suffer from a chronic inflammatory bowel disease (ulcerative colitis, Crohn’s disease), the absorption of nutrients in your bowel is impaired. Chronic stress can also cause a zinc deficiency.^{[9, 16]}

Did you know that people with diabetes have a high risk of developing zinc deficiency? High blood sugar levels lead to frequent urination: poorly adjusted diabetics lose much more zinc in their urine.^{[9, 11]}

What causes poor zinc absorption?

Although cereals, nuts and pulses also contain zinc, they also contain anti-nutrients. These prevent the intestines from properly absorbing zinc. This group of substances includes:^[17]

• Phytate in wholegrain cereals (exception: sourdough bread)
• Phosphate in cola, meat, fish
• Histidine in dairy products
• Oxalate in spinach, rhubarb, beetroot
• Tannins in wine, black and green tea

Phytate forms insoluble complexes with zinc, so that zinc cannot carry out its function in the body. In order to reduce the phytate content, you can soak grain several hours before preparation.^[4]

Did you know that the zinc requirement for people who eat a purely plant-based diet is increased by 50 per cent. Plant-based foods contain anti-nutrients, which is why zinc is less easily absorbed.^[9]

What are typical zinc deficiency symptoms?

Zinc is needed all over the body, so a deficiency will cause significant discomfort. If you have a zinc deficiency, your hair may fall out and your nails may become brittle. Additional zinc deficiency symptoms are:^[4]

• Slow wound healing
• Impaired vision at nighttime, impaired sense of smell
• Fatigue, depressive moods
• Increased susceptibility to infections, diarrhoea
• Severe weight loss, muscle cramps
• Erectile dysfunction

How do you fix zinc deficiency?

An optimal supply of zinc is a question of eating the right things – that is, eating zinc-rich foods. You can ensure this if you know which foods contain zinc and which sources of zinc your body can absorb best. It gets more complicated when it comes to consuming dietary zinc supplements. There are big differences in the quality and consequently in how well your body absorbs supplements.

Please note: Do not use supplements until you have confirmed a zinc deficiency. Otherwise, you run the risk of developing a zinc surplus!^[4]

Animal proteins support the absorption of zinc. Together, they form a complex that the body can utilise very well. Other nutrients that promote zinc absorption are:^[17]

• Histidine in almonds, peanuts, beef and pork
• Methionine in quark, almonds, cod, mackerel, tuna 
• Cysteine in almonds, peanuts, beef and pork
• Citric acid in apples, pears, berries and citrus fruits

Sources of zinc: why take zinc supplements?

If you have a proven zinc deficiency, zinc supplements may help. Zinc supplements can be found in every form imaginable: effervescent tablets, powder, capsules, lozenges, drops or as ointments. What makes a good zinc supplement effective is not the type of supplement but the zinc compound it contains. Zinc only exists in combination with other substances, which are supposed to improve zinc absorption.^[7]

Please note: In addition to the usual supplements, you can also buy nasal sprays containing zinc. They are not recommended, however. These zinc nasal sprays can lead to a deterioration or in the worst case to a loss of your sense of smell.^[7]

Which zinc compound is the best one?

Several studies suggest that the following zinc compounds have an optimised bioavailability:^[18–25]

• Zinc histidine – only compound with no known side effects
• Zinc picolinate – used for better zinc absorption
• Zinc gluconate – used for creating cold remedies
• Zinc sulfate – only effective when taken on an empty stomach; used to boost zinc levels in the body
• Zinc orotate – used for treating some zinc deficiency symptoms in combination with orotic acid
• Zinc citrate – used for preventing zinc deficiency and treating diarrhoea^[31]

Bioavailability describes how well your body absorbs a nutrient and how well it can subsequently work in your body.^[4]

How does zinc react with other medications?

Minerals compete with each other and can prevent each other from entering the bloodstream through the small intestine. Zinc supplements can thus impair the effect of antibiotics, rheumatic drugs such as penicillamines and diuretics such as thiazide diuretics. Therefore, it is recommended to use zinc supplements a few hours before or after taking these medications.^[7]

How are zinc and biotin linked?

Zinc supplements are often added to biotin. This vitamin is also used to promote hair growth, as biotin deficiency can lead to hair loss. Zinc also increases the activity of biotin, which is why it makes sense to take them together. Through your diet, you consume biotin in the form of wholegrain products, mushrooms and meat.^[3]

The body cannot ingest any number of minerals at once because they interfere with each other’s absorption. Therefore, you should not take the following iron, copper or calcium at the same time. Researchers have found that iron is not absorbed over a long period of time if large amounts of zinc are ingested at the same time.^[11]

How does zinc help your skin?

Zinc is becoming very popular in dermatology. Dermatological studies have shown that zinc helps in the treatment of skin diseases such as warts, acne, rosacea and basal cell carcinoma. Zinc is used externally (topically) – that is, in the form of ointments and creams, or orally – that is, as tablets.^[13]

Even the cosmetics industry uses zinc: sunscreens and anti-dandruff shampoos contain zinc as additional UV protection and to suppress dandruff. The mineral also reduces oil production in the skin. Oily skin is the ideal breeding ground for bacteria, which can lead to infections – especially if the immune system is weakened by a zinc deficiency.^[26]

Did you know that zinc ointments with zinc oxide can help with sunburn. Zinc oxide helps damaged skin regenerate! To find out more about summer skincare, head over to our dedicated Health Portal article.^[7]

What happens if you get too much zinc?

Not only zinc deficiency can become a risk to your health. Too much zinc can also harm you. A maximum intake of 25 milligrammes of zinc per day is considered safe. If you exceed this limit for several days, you may already experience initial symptoms. This usually happens because you have consumed too many dietary supplements – it is unlikely to absorb too much zinc through your diet – even with zinc-rich foods.^[4]

If an amount between 225 and 450 milligrammes is ingested at once, severe vomiting may occur. The possible consequences of excess zinc are gastrointestinal problems, kidney dysfunction, diarrhoea, hair loss and iron deficiency. Too much zinc hinders the absorption of iron, so that blood formation becomes impaired – leading to anaemia.

The trace element copper also loses its efficacy when zinc levels are too high. As a result of this copper deficiency, numbness and weakness may occur in the limbs. The same applies to calcium and magnesium, with which zinc competes in the body: calcium and magnesium deficiency can lead to bone loss and a significantly reduced performance.^{[1, 3, 8, 27]}

A zinc surplus can lead to a reduction of the HDL cholesterol. It is considered the healthy cholesterol. HDL cholesterol repairs damage to our cell membranes and removes the harmful LDL cholesterol that causes arteriosclerosis.^[9]

Zinc poisoning can occur in people who use dental glue on a daily basis. It usually contains zinc. You should not use more than 1.5 grammes of the paste per day!^[9]

Do zinc supplements help with the common cold?

Many companies advertise zinc as a miracle cure for colds. Promises made include that it reduces a runny nose, sore throat and constant sneezing. One thing is clear: your immune system cannot function without zinc. This is why it is assumed that the mineral can fight off your cold.

According to the German Nutrition Society (DGE), however, the studies on zinc and its effect on colds is far from clear. The DGE advises to resort to zinc supplements for colds only if you have a proven zinc deficiency. A study conducted by the Cochrane Collaboration in 2012 found that 75 milligrammes of zinc per day reduced the time taken to recover from a cold by one day. However, this only happened if the study participants took the drug within 24 hours of the onset of the first symptoms.^{[7, 28]}

How can I test my zinc levels at home?

Both a zinc deficiency and a zinc surplus will pose problems for your health. However, you can counteract both by testing your zinc levels. You can test your zinc levels with a blood test, for example.

How can I measure my zinc levels?

You can also test your zinc levels yourself – for example, with a mineral test. All you need is to extract a small amount of blood via finger prick. Your sample will then be analysed in a laboratory, which will then provide you with your results. These tests may also give you insights into your magnesium and selenium levels – as these are common mineral deficiencies.^[29]

Some suppliers measure zinc levels by means of a hair analysis. A three-year study has concluded that this method can also provide information about the current mineral supply. This is particularly the case in children who eat too little – this method has proved to be suitable for developing further treatment methods for them.^[30]

Zinc deficiency and foods with zinc – at a glance What is the function of zinc in the body? Zinc is an essential mineral that is found everywhere in your body, but especially in your muscles. This mineral is important for cell division, wound healing, hair growth, blood sugar regulation and immune defence. What are zinc-rich foods?  Oysters are particularly rich in zinc. Other animal sources of zinc, such as cheese, eggs and offal are better utilised by the human body than zinc from plant-based foods. Who is particularly at risk of a zinc deficiency? Athletes, pregnant and breastfeeding women, vegetarians and vegans as well as people with chronic inflammatory bowel diseases have an increased risk of low zinc levels. They either lose large amounts of zinc or their intestines cannot absorb it sufficiently. What are typical zinc deficiency symptoms?  Hair loss, skin problems, diarrhoea and slow wound healing are common zinc deficiency symptoms.

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