Help fight colds and flu with zinc

by Dr. Mercola

• Now that daylight is waning, cold and flu bugs are ready to jump on any warm body not armed with a strong immune system. With so many novel herbs and supplements on the market, it’s easy to lose sight of the basics for robust immune defences.

One of those is the trace element zinc. Your body needs zinc every day in just the right amount because too much can be as harmful as too little. Your body has no way to store zinc so it depends on a daily supply through diet. Zinc is important for a number of life-sustaining functions, including:

  1. Strong immunity.
  2. Important component of the enzymes involved in tissue remodelling and prevention of cancer.
  3. Maintenance of your mood, mental clarity and restorative sleep.
  4. Prostate and intestinal health.
  5. Senses of taste and smell.

Zinc is a constituent of at least 3,000 different proteins in your body and a component of more than 200 different enzymes. In fact, zinc is involved in more enzymatic reactions in your body than any other mineral. Zinc increases your production of white blood cells and helps them fight infection more effectively. It also increases killer cells that combat cancer, helps your immune system release more antibodies and supports wound healing.

Could you be deficient in zinc?

Mild zinc deficiency is relatively common, especially in infants and children, pregnant or breast-feeding women, the elderly, people with poor gastrointestinal absorption or bowel disease like Crohn’s disease and for those eating vegetarian or vegan diets. A number of factors contribute to the overall problem of zinc deficiency:

Years of commercial farming practices, such as monocropping (planting large expanses of land with the same crop year after year), have left our soils deficient in natural minerals like zinc.

Certain drugs deplete your body of zinc, such as ACE inhibitors, thiazide diuretics and acid-reducing drugs like Prliosec and Pepcid.

Certain diets, such as vegetarian/vegan diets and high-grain diets, are low in bioavailable zinc and high in phytic acids, which further impair zinc absorption.

Mild zinc deficiency can lead to frequent colds and flu, chronic fatigue and poor general health. In your child, when growth and development are vitally dependent on good nutrition, inadequate zinc can result in mood disturbances, poor memory, impaired learning and poor school performance. Zinc deficiency can also contribute to acne and poor eyesight. Chronic zinc deficiency can affect eyesight, taste, smell and memory. White spots on your fingernails can indicate you’re not getting enough zinc.

Zinc is a key mineral for your immune health

If your body has inadequate zinc stores, you will experience increased susceptibility to a variety of infectious agents. Your white blood cells simply can’t function without zinc. Zinc affects multiple aspects of your immune system, including neutrophils, natural killer cells, phagocytosis, cytokine production, antibody production and even gene regulation within your lymphocytes. Zinc is involved in many basic cellular functions, including DNA replication, RNA transcription, cell division and activation and stabilization of cell membranes.

The research on zinc’s effect on pathogens is a bit inconsistent, but many studies show a strong protective effect. Some studies show that zinc may reduce the duration of your cold by 50 percent. The Cochrane Review [] found that zinc reduced both the duration and severity of symptoms of the common cold. And using zinc helped prevent colds, leading to fewer school absences and less antibiotic use by children. Zinc is the hallmark molecule for thymic proteins, which are immune substances made by your thymus gland. Without zinc, you lack this immune defence. Zinc salts are deadly to many pathogens. Viral gastroenteritis is slowed down by the ingestion of zinc due to direct antimicrobial action of the zinc ions in your gastrointestinal tract.

If you’re pregnant, zinc is even more important

There is rarely a more nutritionally demanding time during a woman’s life than pregnancy (and later breastfeeding) when the intake of nutrients from foods and supplements are needed not only to keep her body running, but also to nourish and support her rapidly growing baby. Because zinc is required for proper cell division, it is vitally important to get adequate zinc during this time. Low zinc levels have been associated with the following:

  • Premature birth
  • Low birth weight babies
  • Growth retardation
  • Preeclampsia

One study found that zinc supplementation in pregnancy resulted in babies with significantly larger head circumference and higher birth weight. Zinc has many other important functions in your body.

High grain diets directly linked to zinc deficiency

High grain diets can lead to a number of health problems, including severe zinc deficiency, which, in turn, can lead to rickets and dwarfism. According to nutrition expert Dr. Loren Cordain: “It is thought that the high levels of phytate in unleavened whole grain breads cause a zinc deficiency, which, in turn, is responsible for hypogonadal dwarfism, along with other health problems associated with zinc deficiencies. In Europe, where immigrant Pakistanis consume high levels of unleavened whole grain breads, rickets among their children remains a problem.”

Why is this? Grains are high in phytic acids (as are legumes, seeds, and soy) and phytic acids are known to impair your absorption of minerals such as calcium, iron, magnesium and zinc. People in Western populations most at risk are those with diets high in unrefined grains, legumes, soy protein and calcium and low in animal protein.

Protein assists with zinc absorption. Animal proteins increase zinc absorption in general. Vegetarian and vegan diets, often high in grains and legumes, contain more phytic acid and may increase your risk for zinc deficiency. This is just one of many reasons I don’t recommend eating a lot of grains.

How to optimize your zinc levels

As always, it’s best to optimize your nutrition by implementing a diet rich in whole foods to receive your zinc requirements. Animal products are by far the richest in dietary zinc… Oysters tip the scales at up to 182mg per serving!

If, for whatever reason, you are not getting enough zinc, or are a vegetarian… you may want to add a zinc supplement. But what kind of supplement should you take?

Chelated forms of zinc are better absorbed

There are a number of forms of zinc available on the market, some better than others. Your body does not easily absorb zinc unless the zinc is first attached to another substance. Chelation is a process sometimes used to attach zinc to other substances to make it more absorbable and bioavailable. In chelation, the organic molecules have been electrically charged, which allows them to attract the zinc. One advantage of chelated forms is you won’t get antagonism with calcium, which can be an issue for zinc salts, such as zinc sulfate.

Zinc sulfate is one of the inorganic forms of zinc, or zinc salts. These are not as biologically effective as chelated forms. Zinc sulfate can cause stomach irritation. Another inorganic variety is zinc oxide, which is the form of zinc used in many sunscreens.

Other good forms of zinc include zinc gluconate, which is made essentially by fermenting glucose, zinc acetate, made by combining the zinc with acetic acid and zinc citrate, made by combining the zinc with citric acid. It’s advantageous to take a supplement with a variety of forms, if possible. The current RDAs for zinc are listed in the following table:


Age Male Female Pregnancy Lactation
6 mo 2 mg 2 mg
7 mo-3yrs 3 mg 3 mg
4-8 yrs 5 mg 5 mg
9-13 yrs 8 mg 8 mg
14-18 yrs 11 mg 9 mg 12 mg 13mg
19+ yrs 11mg 8mg 11mg 12mg

These recommended doses are for elemental zinc and each form of zinc (zinc sulfate, zinc citrate, zinc gluconate, etc.) contains a different amount of elemental zinc. The amount of elemental zinc a supplement contains will be listed in the Supplemental Facts panel on the supplement container.

For example, approximately 23 percent of zinc sulfate consists of elemental zinc. Therefore, 220 mg of zinc sulfate would give you about 50 mg of elemental zinc. You must take this into consideration if you’re going to use a supplement, as well as the fact that the average person gets about 10 to 15 mg of zinc per day from the foods you consume. You will have to use your best judgment in determining if you are at the upper or lower end of that range, based on your dietary habits and supplement accordingly.

Too much of a good thing

Foods and medications can interfere with absorption so the timing of your supplement is important. For example, caffeine can interfere with zinc absorption of zinc by as much as 50 percent so you will want to avoid chasing down your supplement with a cup of coffee. By contrast, the amino acids cysteine and methionine improve zinc absorption, which means taking your zinc supplement with a high-quality whey protein would be a dynamite immune-boosting duo.
Although it is important to get adequate zinc, balance is key. Taking too much can also cause problems, although it generally takes fairly high doses over time to reach toxic levels. Chronically excessive zinc intake can suppress copper and iron absorption leading to deficiencies in those minerals.


In conclusion, zinc is an often forgotten nutritional staple to add to your flu-busting arsenal. It’s inexpensive insurance that can stop those viruses dead in their tracks. In addition to making sure you’re getting enough zinc, don’t forget how important your vitamin D levels are for keeping you healthy this winter.

© Dr. Mercola. For more research information, visit

photo of zince tablets © Jovani Carlo Gorospe

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