*Not all products in this category have an EFSA-approved health claim. Products with an EFSA claim are described as such in the text. The other products are grouped under this theme on the basis of traditional use or product formula. For specific health questions, we recommend consulting a doctor or orthomolecular therapist.
Written by the Plenthera team (orthomolecularly trained). Scientifically reviewed in October 2026. Last updated: 7 October 2026.
The immune system works best when you support it, not when you push it. In the Netherlands and much of Northern Europe, low vitamin D status is widespread from October to March. The basis is therefore vitamin D3, supplemented with vitamin C and zinc, all three of which contribute to the normal function of the immune system. In this category you will also find colostrum, cod liver oil, black seed oil and live cultures — foods and supplements that fit into a winter routine.
Which immune stack suits you?
| Situation | Stack | Timing |
|---|---|---|
| Winter basis (October–March) | Vitamin D3 + vitamin C + zinc | Daily with breakfast |
| Little time outdoors, 50+ or darker skin | Vitamin D3 all year round + vitamin C | Daily |
| Athlete in winter | Vitamin C 200 mg extra + D3 + zinc | Daily |
| Gut and resistance | Live cultures + colostrum + vitamin D3 | Daily |
| Traditional winter routine | Cod liver oil + black seed oil + vitamin C | Daily with a meal |
What is immunity & resistance?
The immune system consists of two parts: innate immunity (fast and non-specific) and acquired immunity (slower and specific, via antibodies and T cells). Both need nutrients. Vitamin D, vitamin C, zinc, copper, selenium, iron, vitamin A, B6, B12 and folate contribute to the normal function of the immune system; a deficiency in any of these substances weakens your defences.
Vitamin D is the most important link in the Netherlands and much of Northern Europe. From October to March, the sun is too low for the skin to produce vitamin D, so a large part of the population has a low 25(OH)D level in winter. The Health Council of the Netherlands therefore advises 10 µg per day for women aged 50 and over, men aged 70 and over (20 µg), people with darker skin and those who rarely go outside; for others, supplementation in winter is a sensible choice. Recommendations may differ in your country. Vitamin D contributes to the normal function of the immune system.
The classic winter stack is D3 + C + zinc: all three with an authorised claim for the immune system. Vitamin C also contributes to the protection of cells from oxidative stress and, at 200 mg extra per day, to maintaining the normal function of the immune system during and after intense physical exercise. Zinc and copper work together: those who take zinc for a long time should keep an eye on their copper intake.
Around 70% of immune cells are located in the gut wall. That is why live cultures and colostrum belong to this theme: there is no authorised claim, but both are being researched in relation to the gut and resistance. The same applies to mushroom extracts (reishi, chaga, AHCC) with beta-glucans, which you will find among the superfoods.
Immunity & Resistance and EFSA — what is scientifically recognised?
EFSA has not authorised an overarching resistance claim. However, there are components with relevant authorised claims under Regulation (EU) 432/2012:
'Vitamin D contributes to the normal function of the immune system.'
'Vitamin C contributes to the normal function of the immune system.'
'Vitamin C contributes to maintain the normal function of the immune system during and after intense physical exercise.' (at 200 mg per day in addition to the recommended daily intake)
'Zinc contributes to the normal function of the immune system.'
'Copper contributes to the normal function of the immune system.'
'Vitamin A contributes to the normal function of the immune system.'
'Vitamin B12 contributes to the normal function of the immune system.'
'Vitamin E contributes to the protection of cells from oxidative stress.'
The claims apply at a daily dose that provides at least 15% of the reference intake (vitamin D 0.75 µg, vitamin C 12 mg, zinc 1.5 mg, copper 0.15 mg, vitamin A 120 µg, B12 0.375 µg, vitamin E 1.8 mg). There is no authorised claim for colostrum, live cultures, black seed oil as such, astaxanthin and mushroom extracts; we describe them in terms of research context and traditional use.
The immune stack at Plenthera
Vitamin D3
Vitals Vitamine D3 3000 IE (75 µg, vegan softgels) and D3 drops (20 ml), the combinations Plent D3 + K2 (50 µg + 75 µg MK-7), Vitals Vitamine K2 + D3, Arthur Andrew KD Ultra® and Trace Minerals Ionic D3 + K2 (liquid; 125 µg per label serving is above the upper limit of 100 µg derived by EFSA — stick to a lower dose or choose another product), plus Vitals Bot- en Tandformule Pro. Add up the vitamin D from several products.
Vitamin C
Plantforce Vegan Vitamine C-Complex (acerola and lemon; 500 mg of vitamin C per 2.5 g, 100 or 200 g) from the Danish brand Plantforce and Vitals Ester-C 1000 mg (90 tablets). Vitamin C contributes to the normal function of the immune system and to the reduction of tiredness and fatigue.
Zinc and copper
KiKi Health Ionic Zinc (10 mg per 30 drops) and Trace Minerals Ionic Copper (3 mg per ¼ teaspoon). Zinc and copper contribute to the normal function of the immune system; the upper limits derived by EFSA are 25 mg of zinc and 5 mg of copper per day.
Colostrum
Big Food Whole Colostrum (250 g, full-fat, from Dutch cows) and Real Roots Colostrum defatted (150 g). Colostrum (beestings) is the first milk after calving, rich in protein and immunoglobulins; it is being researched in relation to the gut and resistance.
Cod liver oil and black seed oil
Nordic Naturals Arctic Cod Liver Oil (natural, lemon, orange; EPA and DHA contribute to the normal function of the heart) and Arctic-D with extra vitamin D. Big Food Zwarte Komijnolie (cold-pressed, 90 softgels) provides vitamin E, which contributes to the protection of cells from oxidative stress; black seed is traditionally used in winter.
Live cultures
Arthur Andrew Syntol AMD® (360 capsules) combines live cultures with enzymes. No authorised claim; being researched in relation to the gut flora.
Additional
Vitals Vitamine B12 1000 µg (B12 contributes to the normal function of the immune system), Big Food Runderlever capsules (vitamin A, B12, folate and iron from food), Vitals Elke Dag Platinum and Vrouwenformule Pro 45+ as multivitamins, Vitals Astamax (astaxanthin) and Real Roots Beef Thyroid & Liver and Adrenal & Liver (freeze-dried organ capsules based on traditional use, without a claim).
Other forms on the market
We do not stock echinacea, elderberry, propolis or stand-alone beta-glucans in this category. For echinacea and elderberry, the evidence is mixed and there is no authorised claim.
How do you use supplements for resistance?
A simple basic approach:
- Start in October with vitamin D3 according to the label and continue until the end of March; if you belong to a risk group, all year round.
- Add vitamin C and zinc at breakfast; if you take zinc long term, add copper too.
- Take fat-soluble vitamins (D, A, E, cod liver oil) with a meal containing fat.
- Gut and resistance: live cultures and colostrum daily, according to the label.
- Do not exceed the recommended daily dose; add up the vitamin D and zinc from several products.
- Combine with sleep, exercise outdoors, hand washing and — from the age of 60 or for risk groups — the flu jab.
- Do you take immunosuppressive medication or blood thinners (vitamin K in D3+K2 combinations), or are you pregnant? Consult your doctor first.
- With recurring or long-lasting infections: seek medical care, not self-medication.
Myths and misconceptions about immunity & resistance
Myth 1: 'You can boost your immune system.'
A 'boosted' immune system does not exist; you can prevent deficiencies so that it works normally. That is what the claims are about.
Myth 2: 'The more vitamin C, the better.'
Above about 1 g per day, absorption drops sharply and it can cause gastrointestinal complaints. A normal daily dose works better than megadoses once you are already ill.
Myth 3: 'Supplements prevent colds.'
No supplement prevents infections. Vitamin D and zinc help prevent a deficiency; hand washing and sleep do the rest.
Myth 4: 'Supplements work instantly.'
Vitamin D status rises over 4–8 weeks. Start in good time.
Combining Immunity & Resistance with other supplements
Resistance does not stand on its own. Combinations that make sense:
- Sleep & Relaxation: lack of sleep measurably weakens your defences.
- Digestion & Gut: live cultures, enzymes and psyllium for the gut.
- Energy & Tiredness: iron and B vitamins also contribute to the normal function of the immune system.
- Vitality mushrooms: reishi, chaga and AHCC with beta-glucans.
- Omega 3: EPA and DHA contribute to the normal function of the heart.
Frequently asked questions
Which supplements fit the immune system?
Vitamin D, vitamin C, zinc, copper, vitamin A, B6, B12, folate, iron and selenium all contribute to the normal function of the immune system. The basis in winter is vitamin D3, vitamin C and zinc.
How much vitamin D in winter?
The Health Council of the Netherlands advises 10 µg per day for groups including women aged 50 and over, people with darker skin and those who rarely go outside, and 20 µg for everyone aged 70 and over; recommendations may differ in your country. The upper limit derived by EFSA is 100 µg per day.
Does a high dose of vitamin C help with a cold?
In meta-analyses, daily intake of vitamin C slightly shortens the duration of a cold; only starting at the first symptoms has little effect. Vitamin C contributes to the normal function of the immune system; stick to the label.
How much zinc per day?
The reference intake is 10 mg; the upper limit derived by EFSA is 25 mg per day. KiKi Ionic Zinc provides 10 mg per serving.
What is colostrum?
Colostrum (beestings) is the cow's first milk after calving, rich in protein and immunoglobulins. There is no authorised health claim; it is being researched in relation to the gut and resistance.
Are live cultures useful for resistance?
They are being researched in relation to the gut flora, where a large part of the immune system is located. There is no authorised claim.
When should you take these supplements?
With breakfast or another meal containing some fat, for the absorption of vitamins D, A and E.
How long before I notice anything?
Vitamin D status rises over 4 to 8 weeks. So start in October, not once you already have a cold.
Sources
- Regulation (EU) 432/2012 — claims for vitamins D, C, A, E, B12, zinc and copper.
- Health Council of the Netherlands (2012). Evaluation of the dietary reference values for vitamin D.
- EFSA (2023). Scientific opinion on the tolerable upper intake level for vitamin D; EFSA (2014/2024). Tolerable upper intake levels for zinc and copper.
- Hemilä H. & Chalker E. (2013). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews.
- Martineau A.R. et al. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ.
- Calder P.C. et al. (2020). Optimal nutritional status for a well-functioning immune system is an important factor to protect against viral infections. Nutrients.
Disclaimer: This text is for information purposes only and does not replace medical advice. Supplements are food supplements, not medicines. If in doubt or if you take medication, we recommend consulting a doctor or orthomolecular therapist first. With serious or persistent complaints, medical care remains the basis.