Zinc: What It Does, How Much We Need, and What Research Says About Colds

In this article

1. What is zinc and what does it do in the body?
2. Why is zinc so popular during cold season?
3. Can zinc prevent or shorten a cold?
4. What happens when we don’t get enough zinc?
5. How much zinc do we need per day?
6. What foods are high in zinc?
7. What are the most common forms of zinc?
8. How do we choose a zinc supplement?
9. How should we take zinc?
10. Can you take too much zinc?
11. Frequently asked questions about zinc
12. Final thoughts

Zinc is an essential trace mineral that supports normal immune function and many other processes throughout the body. It is involved in cell division, DNA and protein synthesis, skin renewal, tissue repair, wound healing, and normal taste and smell.

The body cannot produce zinc and does not maintain large specialized stores for long periods, so we need a regular supply from food. Interest in zinc tends to increase during cold season because of its role in immunity and research into whether certain zinc products can shorten the duration of common-cold symptoms.

What is zinc and what does it do in the body?

Zinc is an essential trace mineral. The body needs it in relatively small amounts, but it plays an important role in many biological processes.

Zinc is required for the activity of nearly 100 enzymes and is involved in processes that take place continuously throughout the body.

We need zinc for:

• normal immune system function;
• cell growth and division;
• DNA synthesis;
• protein synthesis;
• skin cell renewal;
• tissue repair and wound healing;
• normal taste and smell;
• normal growth and development.

Zinc also participates in processes involved in reproduction and development. Adequate intake is important for both women and men, but taking additional zinc does not automatically increase fertility or testosterone levels.

Unlike nutrients the body can produce on its own, zinc must be obtained regularly from food. Meat and seafood are among the most concentrated sources, but zinc is also found in eggs, dairy products, legumes, nuts, and seeds.

Why is zinc so popular during cold season?

Interest in zinc increases during cold and respiratory infection season mainly because of its role in normal immune function.

Zinc is required for the development and activity of several types of immune cells. When zinc intake is inadequate, normal immune responses can be affected.

There is another reason zinc receives so much attention during cold season: researchers have studied for years whether taking zinc after cold symptoms begin can influence how long those symptoms last.

This is why zinc is commonly found in lozenges and other products marketed for cold season.

However, more zinc does not automatically provide better protection. The body needs an adequate amount, not unlimited amounts.

Can zinc prevent or shorten a cold?

These are two different questions.

A 2024 Cochrane review that included 34 studies found that zinc used to prevent colds may have little or no effect on the risk of developing a cold.

Once a cold has already started, however, zinc may shorten the duration of symptoms, although results vary between studies and the certainty of the evidence is limited.

An important detail is that many studies on colds tested zinc lozenges, not ordinary zinc capsules taken as daily supplements.

This means that the findings cannot automatically be applied to every zinc product.

Reported adverse effects included:

• unpleasant or metallic taste;
• nausea;
• digestive discomfort.

In short: zinc has not been shown to clearly prevent the common cold, but certain zinc products may reduce the duration of symptoms once a cold has already started.

What happens when we don’t get enough zinc?

Severe zinc deficiency is less common among healthy people who eat a varied diet, but deficiency can develop when zinc intake is too low or absorption is impaired.

Inadequate zinc may be associated with:

• loss of appetite;
• reduced taste and smell;
• slower wound healing;
• hair loss;
• diarrhea;
• impaired immune response;
• growth and developmental problems in children.

These symptoms are not specific to zinc deficiency and may have many other causes.

The risk may be higher in people with certain gastrointestinal conditions, absorption problems, or restrictive diets.

People who eat predominantly plant-based diets may need to pay particular attention to zinc-rich foods because phytates found in some plant foods can reduce zinc absorption.

How much zinc do we need per day?

Zinc requirements vary according to age, sex, pregnancy, and breastfeeding.

Age / group	Zinc per day
Children 1–3 years	3 mg
Children 4–8 years	5 mg
Children 9–13 years	8 mg
Girls 14–18 years	9 mg
Boys 14–18 years	11 mg
Women 19+ years	8 mg
Men 19+ years	11 mg
Pregnancy, 19+ years	11 mg
Breastfeeding, 19+ years	12 mg

These values represent total daily zinc intake, not the amount that a supplement must contain.

For example, a requirement of 11 mg per day does not automatically mean that a person needs an 11 mg zinc capsule if food already provides some or all of that amount.

For children and teenagers, the amounts in the table also represent total daily intake, not recommended supplement doses.

What foods are high in zinc?

Zinc is found in both animal and plant foods. Oysters are among the most concentrated natural sources.

Food	Serving	Approximate zinc
Cooked oysters	6 medium	27–50 mg
Beef	85 g	~5–9 mg
Crab	85 g	~4.7 mg
Dark turkey meat	85 g	~3 mg
Pork	85 g	~2.7 mg
Roasted soybeans	½ cup	~2.2 mg
Cashews	28 g	~1.6 mg
Sunflower seeds	28 g	~1.5 mg
Plain yogurt	~170 g	~1.5 mg
Cooked chickpeas	½ cup	~1.2 mg
Milk	1 cup	~1.1 mg
Cheddar cheese	28 g	~1 mg

Is zinc from plant foods absorbed as well?

Not always.

Legumes, whole grains, nuts, and seeds contain phytates, which can reduce zinc absorption.

Zinc from meat and seafood is generally more readily available for absorption.

A vegetarian diet can still provide enough zinc, but food choice and variety become more important.

What are the most common forms of zinc?

Zinc supplements are available in several forms. Common forms include zinc gluconate, acetate, citrate, picolinate, and sulfate.

The form can influence how a product is used and tolerated, but there is not enough evidence to say that one form is best for everyone.

Form	What to know	Commonly found in
Zinc gluconate	A common supplemental form and one frequently used in zinc lozenges.	Daily supplements; some cold lozenges
Zinc acetate	Used in supplements and in some lozenges studied for the common cold.	Supplements; cold lozenges
Zinc citrate	A commonly used supplemental form.	Daily zinc supplements
Zinc picolinate	Frequently promoted for absorption, but it has not been shown to be the best choice for everyone.	Daily supplements
Zinc sulfate	A traditional form used to provide supplemental zinc.	Zinc supplements

Studies on the common cold have used different zinc forms and doses, including lozenges containing zinc gluconate or zinc acetate.

Because the studies differ considerably, the evidence does not establish one universally ideal zinc form.

How do we choose a zinc supplement?

The form of zinc is only one part of choosing a supplement.

The first thing to check on the label is the amount of elemental zinc — the amount of actual zinc supplied by the product.

What to check	Why it matters
Elemental zinc per serving	Shows how much actual zinc the product provides
Form of zinc	May influence tolerability and how the product is used
Other vitamins and minerals	Helps identify overlapping nutrients in combination products
Zinc from other supplements	Total zinc intake matters, not only the amount in one product
Why you are taking it	A daily supplement and a zinc lozenge used in cold studies are not the same thing

A higher dose does not automatically make a supplement better.

If a product is being selected specifically for a cold, it is important to distinguish between an ordinary daily zinc supplement and the zinc lozenges studied in common-cold research.

How should we take zinc?

There is no single ideal schedule for everyone. Timing, digestive tolerance, and interactions with other supplements or medications are the main practical considerations.

Question	What to know
Morning or evening?	Zinc can be taken in the morning or evening. There is no evidence that one time of day is clearly more effective.
Before bed?	Some studies have explored possible effects on sleep quality, but the evidence is not strong enough to recommend taking zinc specifically at bedtime.
With or without food?	Zinc can cause nausea or stomach discomfort, particularly at higher doses. If this happens, taking it with food may improve tolerance.
Can zinc be taken with iron?	Doses of 25 mg or more of elemental iron taken at the same time may reduce zinc absorption, so they may be better taken at different times.
Can zinc interact with antibiotics?	Yes. With some tetracycline and quinolone antibiotics, the antibiotic is taken at least 2 hours before or 4–6 hours after zinc.
What about penicillamine?	Zinc can also interact with penicillamine, so administration needs to be separated.

Can you take too much zinc?

Yes. With zinc, dose matters.

Adults generally need around 8–11 mg per day, while the tolerable upper intake level for adults is 40 mg per day, based on total intake.

Too much zinc can cause:

• nausea;
• vomiting;
• abdominal cramps;
• diarrhea;
• headaches;
• loss of appetite.

Zinc and copper

Long-term use of high zinc doses can reduce copper absorption and may eventually contribute to copper deficiency.

This is why a supplement containing 25, 30, or 40 mg of zinc should not automatically be considered a “stronger” or better version of a lower-dose supplement.

More zinc does not automatically mean more benefits.

Written by Victoria, founder and editor of RoutineHealth. This article is for general education and is not medical advice. If you suspect a zinc deficiency, are pregnant, take medications, plan to give zinc supplements to a child, or use high doses for an extended period, speak with a qualified healthcare professional. How we research and correct articles is explained in our Editorial Policy; see also our Medical Disclaimer.

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