Important for immune health, zinc is a mineral making headlines these days. Learn why zinc is important for your immune system and so much more. Find out how your genes impact your need for zinc and discover ways of boosting your zinc status.
Zinc, genetics, and your health:
Zinc is an essential trace mineral that is vital to the way your cells function. Researchers estimate that over 2,500 different cellular functions rely on zinc.[ref]
This mineral is a component of many different types of biological molecules – impacting metabolism, immune function, skin barrier function, and more. Zinc is needed for the function of all cell types.
Dietary zinc insufficiency or deficiency:
We need to replenish our zinc stores daily (or nearly daily) from the foods that we eat. The body doesn’t have a long-term storage reservoir for zinc.[ref]
What happens when you don’t get enough zinc on a long-term basis? Signs of zinc deficiency can include:
- Decreased growth and development in children (a big problem in developing countries)
- Decreased immune function (getting more colds, respiratory or diarrheal illnesses than usual)
- Increased risk of type 2 diabetes (zinc is needed for beta-cell function in the pancreas)
- Impaired wound healing
Zinc supplementation has been shown to cut childhood mortality rates by 50% in developing countries. That is huge![ref]
What causes dietary zinc deficiency? The answer can be summed up as simply a diet that is high in phytates and low in animal foods.[ref][ref] Phytates bind to and reduce the intestinal absorption of zinc. Phytic acid, or phytate, is found in plant seeds, so a diet high in beans, grains, and nuts can be high in phytate, depending on how the food is cooked or processed. Animal protein both contains higher levels of zinc and also increases the absorption of zinc.
While most people in developed nations don’t have frank zinc deficiency, a high percentage still have insufficient zinc intake. This can be especially true for elderly people with a poor diet and reduced intestinal absorption. People who have celiac disease, Crohn’s disease, or alcohol addiction are more likely to have reduced intestinal absorption.
Dietary sources of zinc:
Zinc is found in abundance in oysters, crab, beef, elk, lamb, bison, certain types of mushrooms, and fortified cereals.[ref]
Studies show that people on a vegetarian or vegan diet have a lower daily intake of zinc and are at a greater risk for zinc deficiency.[ref] (See the Lifehacks section below for ways of tracking zinc intake and supplementing.)
Intestinal absorption and regulation:
First, you have to make sure the diet contains enough zinc, and then you also need to be able to absorb the zinc in the right amount. The body tightly regulates the amount of zinc absorbed — you don’t want too much or too little.
Zinc is absorbed in the intestines via zinc transport proteins. These zinc transporters are part of a feedback loop: when zinc levels are low in the intestinal cells, this triggers the formation of more zinc transporters. When the zinc levels increase to the right level, the expression of the zinc transport proteins decreases.[ref] The body is pretty awesome in the way that it can regulate micronutrient levels.
A dietary deficiency in zinc, especially longer-term, can lead to a decrease in mucin production in the intestines. Zinc is one of the micronutrients needed for mucin production. Mucin lines the intestines and keeps bacteria and viruses away from the intestinal epithelial cells. When mucin is decreased, the risk of intestinal diseases and pathogenic infections rises.[ref]
Additionally, zinc is vital in cells that turn over rapidly – like intestinal cells and skin cells. Thus, a deficiency in zinc can cause a problem in the intestinal barrier function relatively quickly.[ref]
The cellular level of zinc needs to be tightly regulated since too much available zinc could cause oxidative stress. Metallothionein (MT) is a protein that can bind to zinc if levels are too high in a cell.[ref]
Zinc and the immune system:
Zinc is vital to the immune system, and a lack of zinc can have detrimental effects including increased susceptibility to infectious diseases.
T-cells are part of our adaptive immune system’s defense against viruses and bacteria. T-cells are a type of white blood cell that is produced in the bone marrow and then travels to the thymus to mature into pathogen fighting cells. The thymus is a small lymph-system organ that is located in the upper chest, behind the breast bone. As we age, the thymus decreases in both size and function due to a process called thymus involution. The thymus is at its maximum size in adolescence.
Due to its significant role in the immune system, zinc deficiency is linked to decreased T-cell function, especially in aging. In animal studies, supplemental zinc increases the thickness of the thymic gland and increases T-cell function.[ref]
Both primary and secondary antibody response is decreased in zinc deficiency.[ref]
Clinical trials show that zinc supplementation (in populations that have dietary insufficiency) can decrease diarrheal illnesses by 18% and pneumonia by 41%.[ref] A 2019 study shows that diarrheal diseases in children still cause more than a half-million deaths each year, worldwide. But this is down considerably over the last couple of decades due to efforts to use oral rehydration along with zinc to combat diarrheal illnesses in kids.[ref]
Zinc has been in the news recently for the connection with COVID-19. Patients with more severe COVID-19 symptoms have lower zinc levels, on average, with more than half reaching the point of full zinc deficiency.[ref] While it is known that having sufficient zinc improves immune function for respiratory viruses, giving IV zinc to hospitalized, severe COVID-19 patients is probably not a magic cure. A retrospective study of NJ hospital patients found no mortality benefit from zinc sulfate.[ref] So if you are worried about your susceptibility to COVID-19, increase your consumption of zinc before getting sick.
Zinc for your skin and hair:
The epithelial cells that make up your skin require zinc, and since these cells turn over quickly, the skin is one of the first places where people notice zinc deficiency. Zinc deficiency can also cause hair loss.
Low zinc is linked to:[ref]
- dry, scaly skin
Epigenetic role of zinc:
Recent research shows that zinc is an important cofactor in several genes that are involved in the epigenetic regulation of gene expression. Essentially, this means zinc is important in certain genes that turn on or off a bunch of other genes.
For example, a zinc transporter (ZIP10) is important in the epigenetic regulation of genes important in skin homeostasis. Other research shows zinc is required for several epigenetic enzymes, including DNA methyltransferases (DNMTs).[ref]
Genetic variants that interact with zinc:
In addition to the amount of zinc in your diet and the absorption of zinc in your intestines, your genetic variants also play a role in how much zinc your body needs.
IL-6 is an inflammatory cytokine, important in the immune response to pathogens and in chronic inflammation. Genetic variants in IL-6 interact with zinc supplementation.
Check your genetic data for rs1800795 -174G/C (23andMe v4, v5; AncestryDNA):
- G/G: may benefit more from zinc supplementation in aging[ref]
- C/G: may benefit more from zinc supplementation in aging
- C/C: typical zinc need in aging
Members: Your genotype for rs1800795 is —.
SLC30A8 gene: Zinc Transport in Beta Cells
The SLC30A8 gene codes for the zinc transporter ZnT-8. This zinc transporter is found in pancreatic beta-cells and transports the zinc from the cytoplasm into insulin secretory vesicles where it stabilizes it and prevents degradation.[ref]
Check your genetic data for rs13266634 (23andMe v4, v5)
- C/C: (most common variant in most populations) increased risk of type 2 diabetes[ref]; zinc supplementation may help lower blood glucose levels if high
- C/T: somewhat increased risk of type-2 diabetes; zinc supplementation may help lower blood glucose levels
- T/T: less common genotype, lower risk for type-2 diabetes
Members: Your genotype for rs13266634 is —.
Check your genetic data for rs11558471 (23andMe v4, v5; AncestryDNA):
- G/G: typical
- A/G: zinc may help to lower blood glucose levels (if zinc insufficient)
- A/A: zinc may help to lower blood glucose levels (if zinc insufficient)[ref][ref]
Members: Your genotype for rs11558471 is —.
SLC30A2: Zinc transporter
This zinc transporter is important in the amount of zinc that is included in breastmilk. Zinc is vital for the growth and development of babies, so low zinc in a mother’s breast milk can cause zinc deficiency in the baby.
Check your genetic data for rs587776926 (AncestryDNA):
- T/T: typical
- C/T: carrier of a zinc transporter deficiency mutation (a problem if breastfeeding a baby)
- C/C: carrier of a zinc transporter deficiency mutation (a problem if breastfeeding a baby)[ref][ref]
Members: Your genotype for rs587776926 is —.
Check your genetic data for rs185398527 G87R (23andMe v5):
- C/C: typical
- C/T: carrier of a zinc transporter deficiency mutation (a problem if breastfeeding a baby)
- T/T: carrier of a zinc transporter deficiency mutation (a problem if breastfeeding a baby)[ref][ref]
Members: Your genotype for rs185398527 is —.
Check your genetic data for rs117153535 (23andMe v5):
- C/C: typical
- A/C: lower zinc in breastmilk
- A/A: lower zinc in breastmilk[ref]
Members: Your genotype for rs117153535 is —.
The SLC39A2 gene codes for zinc transporter ZIP2 controlling zinc influx into the cytoplasm.
Check your genetic data for rs2234632 (AncestryDNA only)
- G/G: typical
- G/T: higher inflammatory cytokines — zinc supplementation reduces
- T/T: higher inflammatory cytokines — zinc supplementation reduces[ref]
Members: Your genotype for rs2234632 is —.
SLC39A13: Zinc transporter ZiP-13
Check your genetic data for rs121434363 (AncestryDNA only):
- G/G: typical
- A/G: carrier of a rare mutation linked to Spondylocheirodysplastic Ehlers-Danlos
- A/A: rare mutation linked to Spondylocheirodysplastic Ehlers-Danlos[ref][ref]
Members: Your genotype for rs121434363 is —.
The CA1 gene codes for a carbonic anhydrases enzyme that uses zinc and catalyzes the reversible hydration of carbon dioxide, important in cellular respiration.
Check your genetic data for rs1532423 (23andMe v4, v5; AncestryDNA):
- A/A: higher serum zinc levels[ref]
- A/G: higher serum zinc levels
- G/G: typical serum zinc
Members: Your genotype for rs1532423 is —.
How much zinc do you need?
The recommended dietary allowance (RDA)for zinc is 11 mg/day for men and 8 mg/day for women. The RDA is usually the minimum needed for an average person to avoid the symptoms of deficiency. We are all unique in our micronutrient needs, so you may need a little more or less than the RDA depending on genetics, diet, and intestinal absorption issues.
The upper daily limit (UL) for zinc is set at 40mg/day. Longer-term supplementation at levels higher than this could result in adverse events, for some people.[ref]
Illness, heavy physical activity, and pregnancy all increase the amount of zinc needed each day.[ref]
More is not always better: Supplementing with zinc, though, can be tricky for some people who get stomach aches from it. If you find that a zinc supplement causes stomach pain, try decreasing the amount, taking it with food, or splitting it into very small doses at a couple of meals. Just because a zinc supplement comes in a 30mg or 50 mg tablet doesn’t mean that you have to take the whole amount at once.
How much zinc are you getting each day from food?
If you don’t eat a lot of shellfish, beef, lamb, or fortified cereals, you may not be getting quite enough zinc in your diet. One way to know is to track what you eat for a week or so.
Cronometer.com is a free web app that breaks down the macro and micronutrients in your food for the day. And – it is free. If you see a pattern of being lower in zinc, then consider adding in supplemental zinc or increasing foods that are high in zinc.
Foods high in zinc include:[ref]
|Oysters, cooked, breaded, and fried, 3 ounces||74.0||673|
|Beef chuck roast, braised, 3 ounces||7.0||64|
|Crab, Alaska king, cooked, 3 ounces||6.5||59|
|Beef patty, broiled, 3 ounces||5.3||48|
|Lobster, cooked, 3 ounces||3.4||31|
|Porkchop, loin, cooked, 3 ounces||2.9||26|
|Baked beans, canned, plain or vegetarian, ½ cup||2.9||26|
|Breakfast cereal, fortified with 25% of the DV for zinc, 1 serving||2.8||25|
|Chicken, dark meat, cooked, 3 ounces||2.4||22|
|Pumpkin seeds, dried, 1 ounce||2.2||20|
|Yogurt, fruit, low fat, 8 ounces||1.7||15|
|Cashews, dry roasted, 1 ounce||1.6||15|
|Chickpeas, cooked, ½ cup||1.3||12|
Zinc interacts with other minerals:
Iron supplements taken at the same time as zinc can cause zinc to not be absorbed. They use the same transporter (DMT1) in the intestines.[ref]
Copper and zinc interact as well when consumed at the same time. The metallothioneins (MT) bind more tightly to copper than zinc, thus displacing the zinc.[ref] There is a balance needed between copper and zinc.
Can zinc be absorbed through the skin?
Anyone with kids knows the magic of zinc oxide cream for diaper rash, and zinc is often included in eczema creams also.
Research shows that zinc can be absorbed topically.[ref] Zinc pyrithione is a common ingredient in skincare products and dandruff shampoo. Research shows that topical application increases zinc in skin cells by 250-fold after 24-hours.[ref]
The formulation of zinc matters a little bit in absorption. For example, zinc 2-pyrrolidone 5-carboxylate is absorbed more readily than zinc oxide or zinc sulfate.[ref]
Will zinc prevent diabetes? Lifehacks for SLC30A1 variant carriers
Maybe. Studies are a bit contradictory on whether increasing zinc reduces the risk for those with the SLC30A1 risk alleles listed above. One study showed that increasing zinc levels by 10 ug/dl decreased the odds of type-2 diabetes for everyone by a little bit, but those with the T/T genotype had a greater decrease than those who carried the C allele (risk genotype). But the majority of studies show that carriers of the rs13266634 C allele are at an increased risk of diabetes. The differences in these studies may be due to the normal dietary intake of zinc in the populations that are studied.[ref][ref][ref]
Safety and side effects:
Stomach aches: As mentioned above, one side effect of zinc supplements can be stomach pain, especially at higher doses. More is not always better, and your body can only absorb a certain amount of zinc at one time. Research shows that 50-300mg/day can cause stomach upset[ref], but some people experience nausea or stomach pain from supplemental doses lower than 50mg/day.
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