During this cold and flu season, you might hear a recommendation that at the first sign of a cold, you should take a zinc lozenge to help ward off the common cold. But are you aware of all the other things that zinc is important for in the body? It’s a powerhouse!
The mineral Zinc
Zinc is the second most abundant trace mineral in the body (after iron). It is a mineral that we can’t store in the body. This means that we need to have some in our daily diet.
What does zinc do?
Zinc has many roles in the body and is vital to the functioning of more than 300 hormones and enzymes. This means that even a mild dietary deficiency can have far-reaching health implications. Some of the key ways in which zinc functions include:
- it is a key component of one of the body’s most important antioxidant enzymes, copper/zinc superoxide dismutase. This enzyme is associated with longevity and protection against oxidative stress.
- supports stomach health.
- can be considered a first line defense in reducing duration and severity of the common cold.
- crucial for supporting immune health and speeding recovery from infections. Zinc activates T-lymphocytes – the immune cells responsible for destroying cells that have been infected with viruses or bacteria.
- involved in the production of testosterone and important for male sexual maturation and reproduction.
- protects against DNA mutation and might play a role in cancer prevention via the T-lymphocytes, particularly cancers of the tongue and esophagus.
- critical for strong bones, healthy skin, and wound healing.
- necessary for insulin synthesis and storage and helps maintain healthy stable blood sugar levels.
- important for eyesight (particularly for night vision), hearing, taste, and sense of smell.
- reduces the risk of age-related macular degeneration.
- involved in acid-base balance.
- necessary for digestion and production of stomach acid.
- tumor suppressor – particularly for prostate cancer.
Why don’t we get enough zinc?
Our body doesn’t store zinc so we need a daily supply in our diet to have adequate levels. Although there are small amounts of zinc in many healthy foods, the only excellent food source for zinc is oysters – and even if you love oysters, you probably don’t eat them daily!! FYI – a typical oyster weighing approx. 1oz will contain about 8-9 mg of zinc. Thus two oysters would be more than the recommended daily amount (RDA). Aside from oysters, there are limited foods that are ‘very good’ or ‘good’ sources of zinc – so you need a combination of foods to get enough each day.
Who is at particular risk for zinc deficiency?
- Some situations mean we have an increased need for zinc, which can result in a relative deficiency. These include:
- medications that deplete zinc, including contraceptive pills, steroids, anticonvulsives, diuretics, tetracyclines, quinolones, bisphosphonates
- drinking more than 2 servings of alcohol a day
- pregnancy and breastfeeding women
- children and adolescents
- serious gastrointestinal problems can impair our absorption of zinc and thus lead to a deficiency. This includes inflammatory bowel diseases – Crohn’s disease and ulcerative colitis, and celiac disease.
- vegans and vegetarians – as the good sources of zinc are beef, grass-fed lamb, and pasture-raised turkey. Particularly if, as a vegan or vegetarian, you eat a lot of processed foods.
- people with
- sickle-cell anemia
- chronic diarrhea
- rheumatoid arthritis
- kidney disease
- liver disease
- people with high levels of phytic acid in their diets (e.g., from legumes) are at risk of zinc deficiency because phytic acid blocks absorption of zinc
- people with the genetic disorder acrodermatitis enteropathica – which involves impaired uptake and transport of zinc
- premature and low-birth-weight infants
- the elderly
Recommended daily allowance for zinc
The recommended daily allowance varies by age and gender:
- Men aged over 19 years – 11mg/day
- Women ages over 19 years – 8 mg/day
- Pregnant women – 11mg
- Lactating women – 12 mg
These recommended levels are the same in both the UK and US.
But these levels do not take into consideration those situations where there is an increased need for zinc, shown above, such as when you’re dealing with an infection.
The upper limit for zinc is 40mg. While for short periods of time it is OK to take zinc at this type of higher level, e.g., to fight off a cold, it is important that this should only be for a short period of time.
Signs of zinc deficiency
Some of the signs of zinc deficiency include:
- altered taste or smell
- impotence in men
- weight loss
- hair loss
- mental fatigue
- slow healing of wounds
- poor night vision
- delayed growth
- white spots on fingernails
However, many of these symptoms are very non-specific and could be caused by any number of conditions, not just zinc deficiency.
Deficiency in developing nations
While mild deficiency in zinc may be present all over the world, in developing countries this is a much more serious issue. In these populations, a deficiency can make people vulnerable to infections such as diarrheal disease, typhoid, cholera, skin infections, pneumonia, and malaria, which can be life threatening. Children are especially at higher risk. Low cost zinc supplementation in these situations is seen to reduce infant mortality.
How do you test your zinc levels?
Testing zinc levels is not straight forward like other minerals. But there are a couple of options.
Zinc taste tally
There is a quick and easy test for zinc sufficiency called a zinc taste test. This is not a definitive test – it just gives you a general indication of sufficiency. You use a specific product like this Zinc Tally or this one. Put 1 teaspoon of the liquid in your mouth and hold it there and swish it around for about 15 seconds.
Consider how it tastes and whether that taste changes with time. You can either swallow it or spit it out after 15 seconds.
If it has an immediate strong unpleasant taste, making you want to spit it out, this suggests that you are not deficient in zinc – so keep making sure you have the RDA.
If you don’t taste anything or it tastes dry or metallic, this suggests you might be deficient in zinc. Consider some extra supplementation and follow your levels by repeating this tally test.
Again, this is not a definitive test – just a rough guide, but it can be useful for monitoring your improving levels of zinc
Other zinc tests
Serum and hair zinc levels are not considered reliable. The most reliable way to test zinc levels is through the Spectracell miconutrient test. This looks at how micronutrients are functioning within your white blood cells.
Food sources of zinc
As mentioned previously, the only excellent food source of zinc is oysters. Very good sources include beef (4mg/4oz), spinach (1mg/cup), asparagus(1mg/cup) , shitake and crimini mushroom (1mg/cup). Good sources are lamb, sesame and pumpkin seeds, garbanzo beans, lentils, cashews, shrimp, scallops, green peas, etc. See more at World’s healthiest Foods.
Supplementing with zinc
There are very few concerns with taking zinc as a supplement as long as you don’t use high levels for long periods of time. Your multivitamin might well provide 100% of the RDA.
If you are deficient in zinc, often 30mg will be sufficient for a month or so, then you can lower the level to the RDA. Use the taste tally as a basic guide.
Zinc comes in different forms but seems to be more easily absorbed in the (bis)glycinate, gluconate or yeast bound forms. I also like the Optizinc which is zinc monomethionine and is well absorbed in the body.
Zinc carnosine as a supplement is great to support stomach health and it also inhibits stomach inflammation and helps eradicate H.pylori infection. If you have been using proton pump inhibitors (PPIs) or other antacid products, try slowly switching to zinc carnosine instead. It doesn’t have all the nasty side effects of long term use of PPIs (including cognitive decline, dementia and Alzheimer’s disease) and is very protective of gastric tissues.
Zinc lozenges are useful during cold and flu season and have been seen to reduce the duration and severity of colds, if taken at the first sign of a cold. Suck on the lozenge slowly – don’t chew it or chomp it down. Zinc acetate is the most tested form for colds. The lozenges might well leave an unpleasant taste in the mouth however. Be aware that some lozenges suggest taking them every 2 hours and they are really high doses (50mg) – so if you are taking them for colds, go for those with 5-10mg per lozenge so you can taken them more frequently for a couple of days.
There are some conflicting reports about zinc nasal sprays so I would avoid those.
Zinc works with lots of different partners or cofactors – and also can work against some things.
- Copper and zinc – too much zinc in the diet or from supplements can impair copper levels. The ratio of copper to zinc is very important in the body and may be more important than actual levels of each. Particularly if you are supplementing with high doses of zinc, make sure you also get some copper. There is more to say on the copper:zinc ratio, so maybe I’ll elaborate in a separate blog post. For now – just be aware that an ideal ratio is roughly 1:1 copper to zinc.
- Optimal levels of zinc are needed to convert beta-carotene into retinol (vitamin A). This is important if you are a vegetarian or vegan and not having vitamin A in your diet. This is involved in the loss of night vision with zinc deficiency, as it means your beta-carotene from, for example, orange colored foods, isn’t being converted into vitamin A.
- High supplemental zinc can inhibit the absorption of iron in the body, especially if taken on an empty stomach.
- High levels of calcium and magnesium might impair the absorption of zinc. If using supplemental calcium, take it at a different time than you take the zinc.
- Riboflavin (vitamin B2) improves zinc absorption.
Take home message about zinc
- Zinc is a very important trace mineral involved in many different reactions in the body including immunity, anti-oxidants, stomach health, and DNA repair and transcription.
- Many illnesses and medications can lead to zinc insufficiencies.
- Testing zinc levels reliably is difficult but as a general guide, the zinc taste test is a good starting point.
- Supplementing is often adequate through a multivitamin. Stick to the RDA unless you are deficient or are using zinc for an infection, in which case use higher levels for only short periods of time.
- Zinc combined with carnosine is a great solution to acid reflux/GERD problems and helps reduce gastric inflammation.