Immune-Support Formulas: Vitamin C, Zinc, Elderberry and Mushrooms - Evidence by Ingredient
Immune-support blends checked ingredient by ingredient: what research covers for vitamin C, zinc, elderberry, echinacea and mushrooms, and where the evidence is missing.
Content last updated . This page has not been medically reviewed.
If a child has swallowed a blend
Some blends contain iron, and NCCIH says iron supplements are a leading cause of poisoning in young children. [3] In the US, call Poison Help at 1-800-222-1222, or 911 if the child is unwell. Do not make the child vomit.Ingredient by ingredient
| Ingredient | What the research covers | Label | Where covered on this site |
|---|---|---|---|
| Vitamin C | A Cochrane review of placebo-controlled trials (2013) found regular supplements did not lower the risk of catching a cold in the general community (pooled risk ratio 0.97, 95% CI 0.94 to 1.00). [4] Colds were somewhat shorter in adults (8%) and children (14%) taking it regularly. [4] Taking it only after symptoms began showed no consistent effect. [4] | Mixed (regular use shortened colds slightly; no prevention in the general population) | More about Vitamin C → |
| Zinc | A 2024 Cochrane review (34 studies, 8,526 people) found zinc may have little or no effect on preventing colds but may shorten colds that have started, with more non-serious side effects. [5] It excluded products that combined zinc with other vitamins, minerals or herbs. [5] | Mixed; low-certainty evidence | Zinc and zinc forms |
| Elderberry | A systematic review found five randomized trials; elderberry may shorten colds, but the evidence is uncertain. [6] NCCIH says some preliminary research suggests symptom relief, and there is no good evidence for COVID-19. [7] | Promising but limited | More about Elderberry → |
| Echinacea | NCCIH says it may slightly reduce the chance of catching a cold, and it is unclear whether it shortens one. [8] | Mixed | Same page as above |
| Reishi and other mushroom extracts | NCI says mushrooms are being studied for effects on the immune system. [9] One 84-day placebo-controlled trial in healthy adults aged 18 to 55 used a reishi beta-glucan product and measured blood immune markers. [10] A review of mushroom supplements in cancer care called the evidence inconclusive for routine use. [11] | Preclinical and biomarker evidence; infection outcomes: insufficient evidence | More about Reishi and other mushroom extracts → |
Changes in blood immune markers are not the same as fewer or milder infections. Proper evidence not found for a vitamin C, zinc, elderberry and mushroom combination preventing infections in healthy adults: we searched PubMed for multi-ingredient immune supplements and for combined vitamin C and zinc trials, and found no usable controlled trials of blends. The searches returned nothing relevant, which is not proof that none exist.
Official amounts to compare with a label
These are UK figures from the NHS (pages reviewed August 2020), for adults aged 19 to 64. US figures from the NIH Office of Dietary Supplements could not be verified, because the site blocked our download, so none are quoted.| Nutrient | Amount the NHS says adults need | Supplement level the NHS says is unlikely to cause harm |
|---|---|---|
| Vitamin C | 40 mg a day [12] | Less than 1,000 mg a day; larger amounts can cause stomach pain, diarrhoea and wind [12] |
| Zinc | About 9.5 mg a day for men and 7 mg for women [13] | Do not take more than 25 mg a day unless a doctor advises [13] |
| Selenium | Not quoted here | 350 micrograms a day or less [13] |
High zinc lowers the amount of copper the body can absorb, which can lead to anaemia and weaker bones. [13] Many people reach these limits by stacking a blend, a multivitamin and fortified foods; NCCIH advises keeping total intake under the safe upper limits. [3] See amounts and duplicate ingredients.
Related
Vitamin C, vitamin D and zinc for immunity · Supporting immune health · Immune wellness safetyFrequently asked questions
Do immune-support supplements work?
For some single ingredients the evidence is limited or mixed. A 2022 review cited by NCCIH found rigorous human studies for only eight of 27 common "immune" ingredients. [1]
Does vitamin C prevent colds?
A Cochrane review found regular vitamin C did not reduce the risk of catching a cold in the general community, though colds were slightly shorter. [4]
Does zinc shorten a cold?
The 2024 Cochrane review says zinc may shorten colds that have started, with low-certainty evidence and more non-serious side effects. [5]
Is elderberry safe?
NCCIH says raw or unripe elderberry is poisonous and little is known about pregnancy or breastfeeding. [7] Ask a clinician or pharmacist, especially if you take medicine.
Can children take immune blends?
Many supplements have not been tested in children. [1] Ask a pediatric clinician, and keep every product out of reach.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: established nutritional role / deficiency treatment, evidence in adequately nourished people, promising but limited, mixed, insufficient evidence, no good evidence of benefit, preclinical, marketing claim.
Safety, medicines and life stages
- Medicines: NCCIH says there are theoretical reasons echinacea might interact with immunosuppressants or caffeine. [8] Anyone taking immune-suppressing medicine should ask a pharmacist before any "immune" product. See medication interactions.
- Allergy: some people have allergic reactions to echinacea, which may be severe. [8]
- Elderberry: raw or unripe elderberries and other parts of the plant contain cyanide-producing substances that can cause vomiting and severe diarrhea. [7]
- Pregnancy and breastfeeding: little is known about elderberry in pregnancy or breastfeeding. [7] NCCIH says many supplements have not been tested in pregnant women, nursing mothers or children. [1]
- Surgery: some supplements may raise bleeding risk or affect anesthesia; tell your care team well beforehand. [1] See supplements before surgery.
- Kidney and liver conditions: this page found no source on these ingredients for those conditions, so ask a clinician or pharmacist.
- Product quality: what is on the label may not be what is in the product. [1] See quality testing and certifications.