Supplements for the Immune System, Graded

Quick answer

Seven nutrients and one multivitamin entry carry a graded claim for normal immune function: vitamins C, D, A and B6, zinc, selenium and copper. All are graded moderate, and each describes getting enough, not taking more. Adults need 75 to 90 mg of vitamin C and 8 to 11 mg of zinc a day.^1,2

Key facts

NIH notes that when people are not short of a nutrient, routine supplements probably add little.^3,4
Vitamin D is the least settled entry: a pooled analysis of 40 trials with 61,589 people found no statistically significant change in how often people fell ill.⁵
More is not better for zinc: 50 mg a day or more for weeks can block copper absorption and lower copper status.^2,6
The adult upper limits are 100 mcg of vitamin D, 40 mg of zinc, 400 mcg of selenium and 2,000 mg of vitamin C a day.^2,7,8,9
A multivitamin can supply several of these nutrients at once, so check the totals before adding single supplements.^10,11

Vitamins C, D, A and B6

Four vitamins have an entry for normal immune function. NIH describes a role for each in the immune system, and the European Union permits the same wording for foods that are a source of the vitamin. The vitamin D entry also reports a pooled trial result that is unsettled.

Contributes to the normal function of the immune system*^1,4,12,13

Moderate evidence

A well-established nutrient function. NIH describes roles for vitamin C in both the first-line and the learned parts of the immune system: it helps keep barrier tissues intact and helps white blood cells multiply and do their work, and these cells hold far more vitamin C than blood does. EU regulators permit this wording for foods that are at least a source of vitamin C. It is about getting enough. NIH notes that when people are not short of a nutrient, routine supplements probably add little, and most people in the United States get enough vitamin C from food.

Amount studied: Recommended intake: 75 mg a day for women and 90 mg for men, from food and supplements

Contributes to normal immune function*^5,14,15

Moderate evidence

NIH lists immune function among vitamin D's roles, and 'contributes to the normal function of the immune system' is a permitted nutrient-function statement in the EU. Whether supplements help people get through the year with fewer respiratory illnesses is unsettled: the latest pooled analysis, covering 40 trials and 61,589 people, found a small effect that was not statistically significant.

Amount studied: The recommended daily intake from food, sun and supplements

Contributes to the normal function of the immune system*^16,17

Moderate evidence

NIH describes vitamin A as involved in immune function, and the EU permits this wording, after EFSA review, for foods that are at least a source of vitamin A. The illness research NIH summarizes was done in young children in low-income countries who were short of vitamin A, so it does not show that extra vitamin A helps well-fed adults. The statement is about getting enough.

Amount studied: The recommended intake: 900 mcg RAE a day for men and 700 mcg RAE for women, from food and supplements together

Vitamin B6 contributes to the normal function of the immune system*^18,19,20

Moderate evidence

A well-established nutrient function. NIH lists immune function among vitamin B6's roles, including the production of lymphocytes, a type of white blood cell, and of interleukin 2, a signaling protein. EU regulators permit this wording for foods that are at least a source of the vitamin. The benefit is about getting enough, not about taking more.

Amount studied: Recommended intake: 1.3 mg a day for adults up to 50, then 1.5 mg for women and 1.7 mg for men, from food and supplements combined

Zinc, selenium and copper

Three minerals have an entry. Each is about what enough of the mineral does, and each entry says plainly that it is not an effect of taking more than you need.

Contributes to the normal function of the immune system*^2,3,21

Moderate evidence

A well-established nutrient function. NIH describes zinc as needed for lymphocytes, the immune cells that respond to specific germs, to form, mature and become active, and for the activity of other immune cells. EU regulators permit this wording for foods that are at least a source of zinc. It is about getting enough: NIH notes that when people are not short of a nutrient, routine supplements probably add little.

Amount studied: Recommended intake: 11 mg a day for men and 8 mg for women, from food and supplements

Contributes to normal immune function*^8,22,23

Moderate evidence

NIH lists helping the body resist germs among the jobs selenium is needed for, and the European Union's list of permitted nutrient statements, drawn up after review by the European Food Safety Authority, includes normal immune function for selenium. It describes what enough selenium does, not an effect of taking more than you need.

Amount studied: Recommended intake of 55 mcg a day for adults, from food and supplements

Contributes to normal immune function*^24,25,26

Moderate evidence

NIH says copper helps maintain the immune system, a review of human and animal studies lists host defense among the functions that require copper, and the European Union's list of permitted nutrient statements, drawn up after review by the European Food Safety Authority, includes normal immune function for copper. It describes what enough copper does, not an effect of taking more.

Amount studied: Recommended intake of 900 mcg a day for adults, from food and supplements

A multivitamin

One entry is about a multivitamin, which can supply several of these nutrients in a single daily serving.

Provides vitamin C, vitamin D, zinc and selenium, which contribute to normal immune function*^27,28

Moderate evidence

Each of these nutrients, along with vitamin A, vitamin B6, vitamin B12, folate and copper, has an established role in the normal working of the immune system, and each carries that permitted wording in the EU list of nutrient-function statements. NIH describes zinc as having a role in immune function. This is about meeting needs. No trial shows that this formula makes people ill less often.

Amount studied: The recommended daily intake of each nutrient, from food and supplements together

How much adults need

Recommended daily amounts for adults, from food and supplements together^{1,2,8,14,16,18,24}
Nutrient	Recommended per day
Vitamin C	90 mg for men, 75 mg for women
Vitamin D	15 mcg (600 IU) from 19 to 70, 20 mcg (800 IU) from 71
Vitamin A	900 mcg RAE for men, 700 mcg RAE for women
Vitamin B6	1.3 mg from 19 to 50, then 1.7 mg for men and 1.5 mg for women
Zinc	11 mg for men, 8 mg for women
Selenium	55 mcg
Copper	900 mcg

Most of the immune entries are about reaching these amounts. They do not ask you to go past them.

Food first

All seven nutrients are in everyday foods. These are among the richest sources NIH lists.^1,2,22

Fruits and vegetables are the best sources, especially citrus fruits, red and green peppers, kiwifruit, broccoli, strawberries, Brussels sprouts and cantaloupe. Some breakfast cereals have vitamin C added.¹

Oysters have more zinc per serving than any other food. Meat, fish and other seafood are the richest sources, eggs and dairy products add some, and fortified breakfast cereals are a major source in the US diet.²

Seafood, meat and poultry are rich sources: 3 ounces of cooked yellowfin tuna has about 92 mcg, canned sardines 45 mcg, cooked shrimp 42 mcg, and a broiled pork chop or roasted beef steak 37 mcg.²²

Plant foods add useful amounts: an ounce of unsweetened baking chocolate has 938 mcg, a medium potato with its skin 675 mcg, half a cup of cooked shiitake mushrooms 650 mcg, an ounce of cashews 629 mcg and a quarter cup of sunflower seeds 615 mcg.²⁹

Fortified foods provide most of the vitamin D in American diets. Almost all US milk is fortified with about 3 mcg (120 IU) a cup, and many plant milks, breakfast cereals and some brands of orange juice, yogurt and margarine have vitamin D added. Cheese and ice cream are usually not fortified.^7,14

Upper limits and who should ask first

Adult upper limits per day^{1,2,7,8,16,18,24}
Nutrient	Upper limit	What it counts
Vitamin C	2,000 mg	Food and supplements together
Vitamin D	100 mcg (4,000 IU)	All sources
Vitamin A	3,000 mcg of preformed vitamin A	Food, drinks and supplements
Vitamin B6	100 mg (US limit)	Food and supplements together
Zinc	40 mg	All sources
Selenium	400 mcg	Food, drinks and supplements together
Copper	10 mg	Food, drinks and supplements together

Taking 50 mg of zinc a day or more for weeks can block copper absorption and lower copper status, reduce immune function and lower HDL cholesterol.^2,6

You take a quinolone or tetracycline antibiotic, penicillamine or a thiazide diuretic. Zinc can interact with them.
You are pregnant, could become pregnant or are breastfeeding. Too much preformed vitamin A in pregnancy can cause birth defects, so ask before taking any vitamin A supplement.
You have a thyroid condition or take thyroid medicine, or you eat Brazil nuts often. Ask before taking selenium.
You take penicillamine or trientine, or 50 mg of zinc a day or more. Ask before taking copper.^2,29
You take levodopa or an anti-seizure medicine such as phenytoin or phenobarbital. Ask before taking vitamin B6.
You have had kidney stones or have kidney disease. Ask before taking vitamin C in large amounts.
You smoke or used to smoke. NIH advises smokers to avoid multivitamins with large amounts of beta-carotene or vitamin A.

Questions people ask

Do I need an immune supplement if I eat a varied diet?

NIH notes that when people are not short of a nutrient, routine supplements probably add little. Most of the entries on this page are about getting enough.^3,4

Is taking more of these nutrients better?

The entries describe what enough of a nutrient does, not an effect of taking more. For vitamin C, white blood cells were saturated at about 100 mg a day, and above about 200 mg a day blood levels rise only a little.^1,13

Can I take zinc, selenium and copper together?

Each has its own upper limit, and zinc at 50 mg a day or more for weeks can block copper absorption. Add up every product you take, a multivitamin included, and ask a pharmacist or doctor first if you take medicines.^2,10

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.