Why is zinc necessary?
Zinc is required in large amounts in the diet because it cannot be stored in the body. Zinc has a whole range of essential functions in the body, essentially breaking down and metabolising foodstuffs, repairing tissues and the correct use of energy. Because so many enzymes depend on zinc for their correct functioning, even a mild dietary deficiency of zinc can have far-reaching health implications. It is estimated that 11mg of zinc are required daily.
Zinc is necessary for many metabolic processes, including:
- the utilisation of carbohydrates, fats and certain vitamins,
- the formation of blood and other connective tissues (see below).
- the formation of hormones
- the correct functioning of the respiratory system – more below.
- In the developing foetus, zinc has a vital role in the correct development of RNA and DNA and is essential for the correct development of the foetus, especially its immune system and brain, as well as the development of the sexual characteristics.
- Later, zinc plays a vital role in the production of sperm and many of the male and female reproductive processes.
- Zinc allows the acuity of the senses of taste and smell.
- Sufficient intake and absorption of zinc are needed to maintain the proper concentration of vitamin E in the blood.
- Zinc also increases the absorption and metabolism of vitamin A.
- In tiny amounts, zinc is necessary for the lungs to do their jobs properly, as Rudolph Ballentine states in Diet & Nutrition (Himalayan Institute Press):
“During the one second that the blood is racing through the tiny capillaries of the lung, the single atom of zinc that is set into the centre of the enzyme carbonic anhydrase is brought into contact with 600,000 of its target molecules (carbonic acid). The result is that each is broken into one water and one carbon dioxide molecule. Only because of the rapidity of the enzyme’s action can the carbon dioxide be freed fast enough from its compounds to leave the blood during that moment on the alveolus when it is separated from the air by only the thinnest of membranes. Our ability to rid ourselves of CO2 through the exhaled air is then utterly dependent on the presence of these critically located atoms of zinc. Yet the total amount of this mineral in the body is so little that it was, up until a few years ago, considered to be of no significance!”
Other therapeutic uses:
- It may help prevent acne and regulate the activity of the oil glands.
- It is required for protein synthesis, collagen formation, and bone formation, so is helpful in cases of broken bones and skin problems,
- Zinc monomethoinine (bound with the amino acid methionine) is a powerful antioxidant and in general zinc assists in a healthy immune system.
- Zinc protects the liver from chemical damage, and is a constituent of insulin.
- Hair loss
- Wound healing
- Rheumatoid arthritis and other inflammatory conditions
- Impaired sense of vision and taste
- The Linus Pauling Institute in Oregon State University reports that diabetics who took extra zinc showed signs of improvement in their symptoms.
What hinders the proper absorption of Zinc?
- Calcium, phosphorus, as well as iron, oppose the action of zinc. This is of importance to women who are pregnant and taking iron supplements. A way around this would be to have a snack of mixed seeds and nuts by themselves every day, as these are high in zinc.
- Copper, another essential mineral, acts like a see-saw with Zinc, the two minerals compete with each other for absorption in the intestines. So, if too much Copper is present in the diet or in the environment (copper cooking pots or water pipes, for example) there might be a risk of Zinc deficiency.
- Toxic metals, such as cadmium and lead, inhibit the absorption of zinc. People who live in polluted areas, near paint or solvent factories, are at a higher risk of environmental contamination, as are people who live near busy roads.
- High fibre foods, such as soy and bran, contain phytates which inhibit the absorption of zinc from the intestine, especially if they are eaten with calcium-rich foods such as cow’s milk and yoghurt. Confusingly, though, whole grains are especially high in zinc.
- Phosphates, present in junk and processed food, also inhibit the absorption of zinc, as do tea and coffee.
What promotes the proper absorption of Zinc?
Zinc is essential for the metabolism of vitamin A, and its absorption is promoted by vitamin D, and citrates in some citrus fruits such as oranges.
Signs of deficiency include:
loss of the senses of taste and smell, impaired night vision
impotence, low sperm count
increased susceptibility to infection and disease
acne, skin lesions and slow wound healing, hair loss and thin, peeling and white-spotted fingernails
in children, delayed sexual maturation, growth impairment
fatigue, the inability to concentrate, behavioural disturbances and memory loss
propensity to diabetes,
Those at risk from zinc deficiency:
Smokers, as cigarette smoke contains cadmium
Alcoholics, as their zinc uptake is impaired, and alcohol increases the excretion of zinc in urine
Pregnant women and breastfeeding women, as the baby leaches zinc from its mother
People with recurrent diarrhea and people who take a lot of laxatives, people on extreme slimming diets,
Those living in an area of high lead pollution. A high absorption of lead leads to zinc deficiency, which might be a cause of hyperactivity in children.
People who live in an area where there is hard water
People with kidney disease, cirrhosis of the liver, diabetes,
People who sweat a lot, including people who do a lot of strenuous exercise as zinc is lost through sweat
People on raw food diets and people who eat a lot of whole grains, as fibre inhibits the absorption of zinc
Vegetarians and vegans. Vegetable sources of zinc often contain phytates, which stop zinc from being bioavailable, which is the same issue as people on raw food diets.
Animal foods high in zinc:
Seafood, especially shellfilsh: Oysters, whelks, winkles, crab, shrimps, anchovies, sardines, lobster, mussels, pilchards, cockles, squid
Liver, heart and kidneys of livestock animals, and their meat.
Dairy: cheddar cheese, parmesan, camembert, eggs.
Vegetable foods high in zinc:
Grains: quinoa, wheat and oats, barley, rye, brown rice,
Seeds and nuts: sesame, pumpkin, cashews, dill, anise, almonds, walnuts, peanuts, hazels
Spices: Indian chai tea and curry powder
Pulses: chickpeas, dried peas, adzuki beans, lentils, butter beans, red kidney beans
Other: shiitake and crimini mushrooms, alfalfa, cocoa powder, tomato paste, figs, pasta, corn on the cob (not GMO).
For this podcast, I used the following sources:
David Ballantine Diet and Nutrition Himalayan Institute Press
Alison Forbes Healthy Eating Penguin
The Linus Pauling Institute at Oregon State University
World’s Healthiest Foods website
And many more.