Zinc: Benefits, Side Effects, Best Time to Take It & More

Zinc

(Zn)

Evidence: Very High
Potential Benefits: High
Safety: Very High

What is zinc?

Zinc is an essential mineral necessary for hundreds of functions in the body related to hormonal health, immune system function, brain health, and more. Zinc supplements are most helpful if you are deficient in this nutrient. If you already get enough from food, you should not need to take it as a supplement. However, it can still improve some aspects of your health beyond the baseline. This article is about the main benefits of zinc as a supplement, its potential side effects, the best time to take it, and more.

What does zinc do?

Just like magnesium, zinc has hundreds of functions in the body.

This mineral is crucial for growth and development in childhood. Particularly, it is necessary for sexual development and to go through puberty successfully.

Zinc is needed for the production of nitric oxide and all proteins. It activates enzymes involved in digestion, thyroid hormone production, and immune system functions.

It allows vitamins A and D, thyroid hormone, stress hormones, and sex hormones to carry out their functions. For example, this mineral is needed to carry vitamin A in the blood, activate it, and use it for vision and cellular communication.

Zinc also protects against infections, oxidative stress, heavy metal toxicity, psychological and emotional stress, and blood sugar problems.

The nutrient also protects the body from lead, mercury, arsenic, and other heavy metals to some extent.

Potential benefits

It is important to note that all of the potential benefits mentioned below are dose-dependent. Generally, the higher the dose, the more pronounced the effects are. However, they do reach a plateau at a certain point. We will discuss the best dosing protocol later in this article.

Many possible benefits fall under the umbrella of ‘correcting a deficiency’ and are therefore not mentioned in the article. If you are deficient, zinc supplements can affect your cognition, performance, and overall health in a remarkably positive way.

Major benefits

Correcting or preventing a deficiency – Zinc deficiency is one of the most common health problems in the world and can be terrible for health and overall quality of life. Fortunately, a severe deficit is relatively rare. A mild deficiency is much more common and can lead to many problems mentioned later in the article. In developed countries, about 1-13% of people are at risk of deficiency while in Asian, African, Middle Eastern, and Mediterranean regions, as much as 68-95% are deficient. If you are experiencing symptoms of deficiency or know that your zinc levels are too low, helping you get back to the optimum is the main benefit of zinc supplements.

Minor benefits

Reduced symptoms of common cold – Very high doses (75+ mg/d) of zinc acetate reduce both the duration and the severity of common colds. This effect almost certainly applies to other forms of Zn. Longdozens may be more effective than regular oral supplements in this regard.
Improved vision – In older adults, supplementing with 80 mg/d reduces the incidence of age-related macular degeneration and protects against vision loss.
Reduced acne – Zinc supplements may reduce acne even in people who already get enough of this mineral.
Increased testosterone – Supplementation with this mineral can help bring testosterone levels back to baseline in people who suffer from low testosterone. This is especially the case in men who ejaculate a lot.
Reduced symptoms of upper respiratory tract infection – Zinc supplements are relatively effective for reducing upper respiratory tract infection duration and severity even in people who already get a sufficient amount of this mineral from food.

Possible side effects

These side effects are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.

Copper deficiency – These two minerals have to be kept in balance as too much of one can deplete the other. The optimal copper:zinc ratio ranges anywhere from 1:2 to 1:15. Because of this, you do not want to go over 40 mg/d of Zn.
Depletion of other minerals – High doses of Zn may deplete other minerals than copper, albeit to a smaller extent.
Nausea – This side effect is not dangerous but can be unpleasant. It usually occurs at doses of 50 mg or more.
Abdominal pain – Pain in the abdomen can also occur when a person takes 50+ mg.
Zinc toxicity – While severe toxicity is rare, taking high amounts of zinc could lead to toxicity over time. Those suffering from toxicity may experience gastrointestinal upset, vomiting, nausea, and dizziness. This is why it’s best to avoid very high doses. Specifically, you want to stay below 20-40 mg a day unless you have a great reason to take more.
Contamination – Contaminated supplements are uncommon in the USA and other well-regulated countries. However, if you wish to buy products from China, India, or other countries without strict regulations, beware that the supplements may be contaminated. Either way, you need to choose the brand you order from wisely. It is highly recommended to check the certificates or read through some reviews for the specific product before you buy it. The FDA (Food and Drug Administration) has the power to regulate dietary supplements but can only do so after they have been on the market for a while. That’s because supplement companies are not obligated to announce to the FDA when releasing a new product on the market. The FDA has to discover the product and test it for potential impurities, which can take a lot of time. During that time, the supplement can be sold on the market even if it’s impure. Also, supplement companies can change their manufacturers without announcing it to the FDA.
Loss of smell – This effect is exclusive to intranasal zinc sprays.

Who should not take zinc?

You should probably avoid taking the supplement if you:

experience a severe adverse reaction after taking the supplement
are deficient in copper (high doses of zinc can further deplete you of copper if you are already deficient)

Who will benefit the most?

You should consider taking the supplement if you:

experience symptoms of deficiency, or you know you are deficient based on blood tests
supplement with copper (these two minerals have to be kept in balance as too much of one can deplete the other; the optimal copper:zinc ratio ranges anywhere from 1:2 to 1:15)
don’t get enough from food (the easiest way to find out how much of this nutrient you are getting in your diet is to track your food intake for a while with Cronometer.com)
suffer from chronic diarrhea (this condition is often caused by zinc deficiency and can worsen the deficiency by further depleting you of this mineral)
vomit a lot (just like diarrhea, vomit depletes Zn)
experience heavy metal toxicity
often stress
have diabetes
drink alcohol
suffer from Crohn’s disease, celiac disease, or other digestive disorders (they tend to worsen zinc absorption)
suffer from sickle cell disease or glucose 6-phosphate dehydrogenase deficiency
take heavy metal chelators, such as bentonite clay, chlorella, spirulina, or DMSA (these often bind to zinc, iron, and other minerals and flush them out of the body)
are on a vegan or vegetarian diet (Plant foods rich in zinc almost always contain high amounts of phytic acid, a compound that decreases the absorption of Zn by about 50%. Therefore, if you only get this mineral from plants, you will need about 16.5 mg/d as a man as opposed to 11 mg/d. If you are a woman, you should try to get 12 mg/d instead of 8 mg/d. In some cases, zinc from foods high in phytates gets absorbed bout 10 times worse than zinc in animal foods.)
ejaculate frequently (one ejaculation costs about 3 mg of Zn)
have a lot of muscle mass and/or are going through a bulking phase (it costs about 9 mg of Zn to create 1 lb of muscle mass)
have a high budget for supplements (assuming that the supplement doesn’t contain impurities, it appears to be safe in most cases and rarely does more harm than good if you stick to regular doses)

Symptoms of zinc deficiency

Zinc deficiency is one of the most common health problems in the world. In developed countries, about 1-13% of people are at risk of deficiency. In Asian, African, Middle Eastern, and Mediterranean regions, as much as 68-95% are deficient.

The most common signs of deficiency include:

frequent infection
dry skin
acne
sore throat
poor appetite
loss of lean body mass
red blisters
pustules
poor growth and impaired sexual development in children
chronic diarrhea

Keep in mind that these signs are just indications of a deficiency. If you experience some or even most of them, it does not necessarily mean you need more zinc. On the other hand, some people may be deficient even though they are completely asymptomatic.

With that said, if you experience many or most of these symptoms, there is a high chance that you are not getting enough zinc. The more of these symptoms you have and the more severe they are, the more likely you are to have a deficiency.

Types of zinc supplements

The different types of zinc supplements include:

Zinc oxide – This is the most popular and cheapest type. The main concern with this form is that it doesn’t absorb as well as the other forms.
Zinc sulfate – Zinc sulfate is very effective at correcting a deficiency and there are many human studies to back it up.
Zinc acetate – This type is also effective but often more expensive.
Zinc gluconate – Zinc gluconate is just as safe as zinc sulfate and acetate and usually cheaper. However, it contains about 2 times less elemental zinc than the sulfate and acetate forms so you would likely need to take two times as much zinc gluconate.
Zinc orotate – This form is about as good as zinc gluconate but usually more expensive.
Zinc citrate – This type is also cheap and absorbs even better than Zn sulfate, gluconate, and acetate. It is the best choice for most people.
Zinc glycinate – This form, also known as chelated zinc, appears to be just as good as the forms above if not better. There aren’t many scientific studies looking at the absorption and efficacy of Zn glycinate but a lot of scientific evidence suggests it can be very effective at fixing a deficiency.
Zinc methionine – The same said about Zn glycinate also applies to the methionine form.
Zinc carnosine – This form is used primarily to support gastrointestinal health.
Zinc picolinate – While this form absorbs at a greater rate than other forms, picolinate binds to zinc very tightly and moves this mineral right into the hair or urine without allowing it to be used by the body. This type is not as reliable and does not seem to have any additional benefits compared to the other forms.

Other than zinc oxide and picolinate, all forms are safe, reliable, and easy to absorb. Of all types of zinc supplements, zinc citrate absorbs the best and is also very cheap.

How much zinc should you take?

The RDA (recommended daily allowance) for this nutrient is 11 mg/d for adult men and 8 mg/d for women. These amounts should be enough for most people to avoid symptoms of deficiency. The RDA for pregnant and lactating women is 11 mg/d and 12 mg/d, respectively.

For most people, 10-15 mg appears to be the best daily target. This amount should provide most of the benefits without meaningful side effects.

Beware that some things increase your need for zinc. For example, each male ejaculation depletes zinc stores by about 3 mg, and putting o lean muscle mass costs about 9 mg per pound of lean muscle (or about 20 mg per kilogram).

Another thing worth considering is phytic acid, a plant compound that decreases the absorption of zinc by about 50%. Therefore, if you only get this mineral from plants, you will need 16.5 mg/d as a man as opposed to 11 mg/d. If you are a woman, you should try to get 12 mg/d instead of 8 mg/d.

In some cases, zinc from foods high in phytates gets absorbed bout 10 times worse than zinc in animal foods. However, the RDA at least partially accounts for this.

Sprouting, fermenting, and soaking all decrease the phytic acid content in food and therefore improve the absorption of Zn. Sour acids in fermented foods and citrus fruits also enhance zinc absorption.

What you also want to keep an eye on is the copper:zinc ratio. These two nutrients have to be kept in balance and the sweet spot is somewhere between 1:2 and 1:15. What generally throws this ratio off is getting too much copper from supplements or certain types of liver. However, zinc supplements with 50+ mg could certainly deplete you of copper.

If you take any dose of copper or a high dose of zinc, consider supplementing with the other mineral as well.

The upper safety limit for zinc is 40 mg/d. Higher amounts may cause problems such as the imbalance between copper and zinc if you take the supplement for a prolonged period. Taking more than 20 mg daily should not be necessary and is not recommended unless you have a great reason to do so.

Food sources of zinc

What matters more than how much Zn you consume is how much you absorb. Zinc from nuts, seeds, legumes, and grains is about 50% harder to absorb because of phytic acid.

The richest food sources include oysters, red meat, organ meats, and wheat germ. These provide enough zinc in 100-200 grams.

Other types of meat, cheese, and most grains, nuts, and legumes generally provide enough in 200-500 grams.

While fruits and fermented foods generally don’t contain much zinc, they significantly increase the absorption of this mineral. Eating these along with zinc-rich foods can improve your zinc status, especially if you are on a vegan diet.

Another thing that can improve the absorption of zinc in plant foods is soaking, sprouting, or fermenting foods that contain a high amount of phytic acid. Doing so decreases the phytic acid content and thus makes the zinc more bioavailable.

The easiest way to find out how much zinc you are getting in your diet is with Cronometer.com. This free app allows you to track all vitamins, minerals, and more.

Best time to take zinc

The nutrient is water-soluble, which means you don’t have to take it with food to absorb it well. Taking the supplement on an empty stomach may be better as taking this mineral too close to when you eat food may worsen its absorption because of phytic acid and other antinutrients in food.

Taking the supplement with food is better if it causes stomach upset when you take it on an empty stomach.

The most important thing to take into consideration is that we can only absorb so much zinc at once. If you wish to take a high dose of the mineral (30 mg or more), you want to separate it into two or more smaller doses and take them about 5 hours apart.

Whether you take the supplement in the morning or the evening doesn’t matter. It does not interrupt your sleep in any way.

Interactions with other supplements

Copper
These two nutrients have to be kept in balance. The optimal copper:zinc ratio is somewhere between 1:2 and 1:15. What generally throws this ratio off is getting too much copper from supplements or some types of organ meats. However, taking 50+ mg of zinc can certainly deplete you of copper over time. If you take any dose of copper or a high dose of zinc, consider supplementing with the other mineral as well.
Folate, Vitamin B12, and Choline
These three nutrients play an essential part in the methylation process. Impaired methylation can hurt zinc absorption.
Heavy metal chelators
Heavy metal chelators, such as bentonite clay, chlorella, spirulina, or DMSA often bind to zinc, iron, and other minerals and flush them out of the body. If you are taking this or detoxifying from heavy metals in different ways, it is a good idea to include Zn supplements but taking this mineral at the same time as the chelators would significantly worsen its absorption.

Where to buy zinc

Amazon seems to be the best option for ordering zinc supplements in most countries. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the internet.

Beware some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.

FAQ

You can take the supplement daily and do not need to cycle it. However, it is certainly not a problem if you don’t take it daily. Not taking the supplement every once in a while could lead to better absorption.

All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes some time that can add up over months or years. The disadvantage of capsules is that they often contain bovine gelatine, which rarely comes from an ethical source.

Yes. The nutrient doesn’t impact your sleep in any negative way in the short term.

The supplements should not become harmful once they exceed the expiration date, but they can lose potency over time.

Keep the supplements in a cold, dark, and dry place, and they should remain just as potent for many months or even years.

Zinc supplements can certainly help with acne and many other skin problems, including dry skin, red blisters, and pustules. This is especially the case if you suffer from a deficiency.

While toxicity is rare, too much zinc in the system can cause some health problems, such as diarrhea, nausea, abdominal pain, and the depletion of copper and possibly other minerals. It is best to stay below 40mg/d a day to prevent these side effects.

Other than zinc oxide and picolinate, all forms are safe, reliable, and easy to absorb. Of all types of zinc supplements, zinc citrate absorbs the best and is also very cheap.

The most common reason people become deficient is that they don’t get enough of this nutrient from their diet. However, many things can hurt your zinc status and increase your need for this nutrient. For example, each male ejaculation depletes zinc stores by about 3 mg, and putting o lean muscle mass costs about 9 mg per pound of lean muscle (or about 20 mg per kilogram). You can also become deficient by getting too much copper. These two nutrients have to be kept in balance.

You may need more of the nutrient if you:
– experience signs of deficiency, or know that you are deficient from blood tests
– are on a vegan or vegetarian diet (Plant foods rich in zinc almost always contain high amounts of phytic acid, a compound that decreases the absorption of Zn by about 50%. Therefore, if you only get this mineral from plants, you will need about 16.5 mg/d as a man as opposed to 11 mg/d. If you are a woman, you should try to get 12 mg/d instead of 8 mg/d. In some cases, zinc from foods high in phytates gets absorbed bout 10 times worse than zinc in animal foods.)
– don’t get enough from food (the easiest way to find out how much of this nutrient you are getting in your diet is to track your food intake for a while with Cronometer.com)
– ejaculate frequently (one ejaculation costs about 3 mg of Zn)
– suffer from chronic diarrhea (this condition is often caused by zinc deficiency and can worsen the deficiency by further depleting you of this mineral)
– vomit a lot (just like diarrhea, vomit depletes Zn)
– experience heavy metal toxicity
– often stress
– have diabetes
– supplement with copper (these two minerals have to be kept in balance as too much of one can deplete the other; the optimal copper:zinc ratio ranges anywhere from 1:2 to 1:15)
– drink alcohol
– suffer from Crohn’s disease, celiac disease, or other digestive disorders (they tend to worsen zinc absorption)
– suffer from sickle cell disease or glucose 6-phosphate dehydrogenase deficiency
– have a lot of muscle mass and/or are going through a bulking phase (it costs about 9 mg of Zn to create 1 lb of muscle mass)
– have a high budget for supplements (assuming that the supplement doesn’t contain impurities, it appears to be safe in most cases and rarely does more harm than good if you stick to regular doses)
– take heavy metal chelators, such as bentonite clay, chlorella, spirulina, or DMSA (these often bind to zinc, iron, and other minerals and flush them out of the body)

The nutrient stays in your system for about 24-48 hours after you consume it.

If you are taking zinc to cure a common cold or a respiratory tract infection, you should see a benefit within a day or two. In the long term, it typically takes about a month of taking the supplement to begin noticing the benefits related to fixing a deficiency.

Most zinc supplements on the market are vegan-friendly but always check the label to be sure. If you buy the mineral in a capsulated form, beware that the capsules often contain animal-based gelatine. Instead, find a brand that puts its products into cellulose capsules.

The nutrient is water-soluble, which means you don’t have to take it with food to absorb it well.

No, it doesn’t. The supplement does not interfere with fasting in any significant way.

References

Most of the information provided in this guide is supported by scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything said in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.

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