This article on zinc is part of an occasional series on vitamins and minerals from 2010
Zinc is sometimes called the “essential toxin”. Unlike other metals such as arsenic, cadmium and mercury, zinc is not only beneficial but also essential for the body to function properly.
Zinc is found in every cell in the body working behind the scenes to keep it functioning normally. In particular zinc helps enzymes to do their job.
What does zinc do in the body?
- Some of the functions include:
- Skin repair and preventing acne, mouth ulcers and stretch marks
- Creating healthy sperm
- Normal fetal development
- Preventing macular degeneration (an aging related vision disorder).Zinc also plays a vital role in:
- Appetite and taste
- Carbohydrate and protein metabolism
- Night vision
- Histamine formation (allergies)
- Preventing hair loss and premature graying
- T3 conversion (in hypothyroidism)
- Preventing PMS, depression, jiggling feet and tooth decay.
Zinc in food
Like another essential mineral iron, animal sources of zinc are better absorbed than the vegetarian ones. Good sources include red meat, shellfish (oysters being the most infamous) and herrings.
There is also zinc in leafy greens, nuts, mushrooms onions and wholegrains. Other than the bio-absorption issue, the actual zinc content in the soil the plant is grown in can influence the mineral level of the food. Conventional farming tends to deplete zinc and magnesium, among other essential nutrients. If your zinc is low, sourcing organic produce for some of your zinc-rich foods may help.
But that is only the beginning of the zinc status equation. Like other nutrients, how much zinc we absorb, require and are able to involves a complex web of co-factors.
To absorb zinc from food and supplements we also need adequate amounts of protein, B6 and vitamin D. Considering most Australians are low in vitamin D this could be a major co-factor in our zinc status. Further more, inadequate vitamin D absorption may be because of low magnesium in conventionally grown food.
Other factors impairing zinc levels
Other than the co-nutrient and soil deficiency issues, zinc uptake can be impaired by too much calcium (e.g. in dairy products), phosphate (high in meat and carbonated drinks), phytates (in some vegetables and wholegrains) or sugar in our diet. How we prepare our zinc rich food can also be a problem, refining grains such as turning them into flour or freezing vegetables reduces the mineral levels.
We sweat out and urinate zinc, so things that increase these actions such as drinking coffee, alcohol, taking diuretics or even exercise can deplete us. Digestive issues that may result in malabsorption problems such as diarrhoea, Crohns or uncontrolled celiac disease will result in zinc loss.
Common medications including the contraceptive pill, oestrogen replacement, ACE inhibitors (for high blood pressure, antibiotics and steroids can reduce our levels, so can stress or surgery.
How do you know if you are low in zinc?
While simple signs like having rough skin, white spots on your nails or thinking food doesn’t taste right may indicate you need more zinc, sometimes the symptoms are not as obvious or more complex, such as feeling depressed or having food allergies.
Many naturopaths still use a special zinc liquid that may indicate your zinc status. However, research has proven the ‘zinc tally’ or taste test, to be unreliable.
Other than increasing zinc through food and supplements, it is important to work out why you are low in this essential mineral in the first place. I tend to find if you are low in zinc you are likely to be low in other nutrients as well, so a full review of diet, lifestyle and medications might hold the key.
For example – a teenager with acne may be drinking lots of milk or is a vegetarian, which could impact on their zinc status. A common treatment for acne is long-term antibiotics and that may further reduce zinc levels and prolong the acne.
There are lots of different types of supplemental forms of zinc available. The better absorbed forms include zinc sulphate, gluconate, chelate or orotate.
Another confusing aspect of supplementation is the term “elemental zinc”. The packaging should supply the type of zinc, how many milligrams (mg) there are but also what that dosage is equivalent to in “elemental zinc”. Use the amount of elemental zinc to guide your dose.
Adults low in zinc should take between 20-30 mg/day of elemental zinc.
This is particularly important in preconception for men and women and during pregnancy if vegetarian.
Long-term zinc supplementation, if not in a balanced complex, may disrupt levels other nutrients (such as copper). It is more important to address the reasons why your levels are low and rule out factors that may be blocking zinc absorption and utilization.
If in doubt, see a naturopath for a holistic investigation into your diet, supplements and lifestyle, to remedy the cause rather than merely treat the symptoms.