Supplements for children: what is safe, what is worth giving, and what should absolutely be avoided

The market for children's supplements in Poland is growing year by year, and parents are bombarded with advertisements for dozens of "strengthening", "immune-boosting", and "concentration" products. The problem is that only a few ingredients have solid clinical evidence of safety and efficacy in children – the rest is often marketing. This article answers the questions every responsible parent asks: what is really worth giving, in what doses, and what to absolutely avoid to not harm the child's health. Safety is the absolute priority here.

KEY INFORMATION
• Vitamin D3 400–1000 IU daily from birth is the standard recommended by the Polish Pediatric Society – as many as 90% of children in Poland have a deficiency of D3 in winter (Płudowski et al., Nutrients 2021).
• DHA omega-3 is safe and important for brain development from infancy; the recommended dose for children aged 4–18 is 200–500 mg EPA+DHA daily.
• Melatonin below the age of 12 – only with a doctor's indication, without long-term use.
• Absolutely avoid: adaptogens (ashwagandha, ginseng), weight loss supplements, vitamin A retinol >2500 IU/day in children <9 lat.

Why are children not "little adults" when it comes to supplements?

A child's body differs from an adult's in several key aspects that have direct implications for the safety of supplementation. Liver metabolism: cytochrome P450 (CYP3A4) – the main enzyme metabolizing drugs and supplements – does not reach full maturity until 6–12 months of age. This means that infants metabolize substances more slowly and differently than adults, which increases the risk of accumulation. The blood-brain barrier in young children is more permeable, meaning that psychoactive substances (including herbs with alkaloids) more easily reach the central nervous system. Hormonal axis: children – especially during puberty – have active hormonal regulation processes that can be influenced by adaptogens and phytoestrogens.

Moreover, clinical studies conducted on adults are not automatically transferable to children – different pharmacokinetics, different reference points for "safe dose", different toxicity thresholds. The basic principle when supplementing children: less is more, every supplement requires consultation with a pediatrician, and unproven benefits do not justify even a small risk. The question "will it harm?" is more important than "will it help?"

Vitamin D3 – the only supplement recommended for all children from birth

Vitamin D3 is the only supplement whose administration from birth is the standard of evidence-based medicine and is recommended by the Polish Pediatric Society, ESPGHAN, and WHO. 90% of children in Poland have levels below 30 ng/ml 25(OH)D3 in winter (Płudowski et al., Nutrients, 2021) – a defined level of deficiency. D3 is essential for bone mineralization, proper functioning of the immune system, regulation of over 200 genes, and proper development of the nervous system. Rickets due to D3 deficiency in infants – still diagnosed in Poland – is a serious, fully preventable complication.

Recommended doses: newborns and infants 0–6 months – 400 IU/day from the first days of life, regardless of the feeding method (mother's milk does not meet the demand, even if the mother has a normal level of D3); infants 6–12 months – 400–600 IU/day; children 1–10 years – 600–1000 IU/day from September to April (or all year if the child has limited sun exposure); adolescents 11–18 years – 800–2000 IU/day. Form: D3 (cholecalciferol), not D2 (ergocalciferol) – D3 is 2–3 times more effective in raising blood levels of 25(OH)D3. Goal: level of 25(OH)D3 30–50 ng/ml in children.

Omega-3 DHA – important for brain development, safe from birth

DHA (docosahexaenoic acid) is an essential component of cell membranes in neurons and the retina. In the last trimester of pregnancy and the first 2 years of life, the brain is particularly sensitive to the availability of DHA – DHA accumulation in the frontal cortex and retina occurs precisely during this window. Observational studies (Innis, American Journal of Clinical Nutrition, 2007) show a correlation between higher DHA intake by breastfeeding mothers and better visual and cognitive development in infants. A meta-analysis by Jasani et al. (Cochrane, 2017, 19 RCT, n=1657 preterm infants): DHA supplementation in preterm infants improved visual test results.

Recommended doses: breastfed infants – DHA comes from mother's milk; mother supplements 200–300 mg DHA/day. Infants fed formula – check the label, most modern formulas contain DHA (aiming for 0.32–0.35% fatty acids from DHA). Children 1–3 years: 100–150 mg DHA/day; 4–18 years: 200–500 mg EPA+DHA daily. Safety: omega-3 DHA/EPA is well tolerated by children, with no documented serious adverse effects at recommended doses. Possible: fishy taste in feeding – forms for children (gummies, flavored drops) mitigate this issue. omega-3 details

Iron – only with confirmed deficiency, never prophylactically

Iron is one of the most commonly abused supplements in children. Iron deficiency anemia is a real problem – affecting about 20–25% of children in Poland in at-risk groups – but routine administration of iron without confirming deficiency is a medical error. Excess iron disrupts the absorption of zinc and copper, can damage the intestinal epithelium (Fenton mechanism – free iron generates reactive oxygen species) and disrupts the composition of the gut microbiota. Excessive iron intake from supplements in children without deficiency does not provide health benefits (Allen et al., Food and Nutrition Bulletin, 2009).

When iron is indicated: confirmed iron deficiency – ferritin <12 µg/l (signal of depletion) or anemia – hemoglobin <110 g/l (children 1–5 years) or <115 g/l (children 5–12 years). At-risk groups requiring monitoring: premature infants and newborns with low birth weight; infants exclusively fed cow's milk after 6 months (cow's milk contains little iron and inhibits its absorption); children on a vegan or vegetarian diet without proper meal planning; children with celiac disease, Crohn's disease, or other gastrointestinal disorders. Dosage in case of deficiency: 3–6 mg of elemental iron/kg of body weight/day for 3 months, then check morphology and ferritin. Only under pediatric supervision.

Probiotics – S. boulardii and LGG have evidence, the rest may be marketing

Probiotics are one of the supplements with the strongest clinical evidence in children – but only for specific strains and specific indications. Saccharomyces boulardii (a yeast, not a bacterium – not eliminated by antibiotics): meta-analysis by Szajewska et al. (Alimentary Pharmacology & Therapeutics, 2015, 21 RCT, n=4780): reduction of the risk of antibiotic-associated diarrhea by 52%; effective for rotavirus and travel-related diarrhea. Lactobacillus rhamnosus GG (LGG): meta-analysis by Szajewska et al. (Journal of Pediatrics, 2007, 9 RCT): reduction of the duration of infectious diarrhea in children by 1–1.5 days; reduction of the risk of antibiotic-associated diarrhea. Both strains are safe for children over 1 year of age.

Important limitations: probiotics are not equivalent – the strain matters. A product described as a "probiotic" without specifying a particular strain (e.g., L. acidophilus NCFM or B. longum R0175) has no documented clinical effects. In premature infants and children with severe immune deficiencies – probiotics only after consultation with a pediatrician (rare cases of fungal sepsis in premature infants with S. boulardii). Form: powder for infants, drops or capsules for older children. Dosage: L. rhamnosus GG 10^8–10^10 CFU/day; S. boulardii 250–500 mg/day (start with antibiotics, continue for 5–7 days after completion).

What to absolutely avoid in children – a forbidden list

The following supplements and preparations should not be given to children without a clear medical indication, and some of them are prohibited below a certain age due to documented risks or a complete lack of safety studies in the pediatric group.

Adaptogens (ashwagandha, ginseng, rhodiola, maca): absolutely no safety studies in children under 16 years old. Adaptogens modulate the HPA axis (hypothalamus-pituitary-adrenal) and potentially other hormonal axes that are critically important for maturation. Reported cases in teenagers: irregular menstruation with ashwagandha, hormonal disorders with ginseng. Even the most advanced clinical studies of these herbs do not include the pediatric population – a lack of safety evidence is the same as evidence of risk in this group.

Melatonin below the age of 12 without a doctor's indication: melatonin affects the circadian rhythm and the hypothalamus-pituitary-gonadal axis. In children under 12, the use of melatonin without indication (e.g., sleep disorders in ASD, ADHD) is not supported by long-term studies. Possible impact on sexual maturation when used for >4–8 weeks. If a child has sleep issues – the first line is sleep hygiene, daily schedule, screen time reduction, not melatonin.

Vitamin A retinol in doses >2500 IU/day in children under 9 years: retinol (preformed vitamin A from supplements, not beta-carotene from food) accumulates in the liver and is toxic in excess. Symptoms of chronic toxicity: headaches, skin peeling, bone pain, liver damage. Beta-carotene (provitamin A from carrots, spinach) is safe – the body regulates conversion to retinol. Avoid multivitamin supplements with high doses of retinol in young children. Weight loss supplements, stimulants, with caffeine and guarana: obviously – no pediatrician recommends this. probiotics details

Zinc and magnesium – when is it worth considering in children?

Zinc is a cofactor for over 300 enzymes and plays a key role in the functioning of the immune system, wound healing, protein synthesis, and proper growth. Zinc deficiency in children – although rare with a varied diet – manifests as slowed growth, frequent infections, poorly healing skin, and appetite disorders. At-risk groups for zinc deficiency include children on a vegan or vegetarian diet (zinc from plant sources is less well absorbed due to phytates), children with celiac disease, and children with frequent diarrhea. Study by Aggarwal et al. (Journal of Pediatrics, 2007): zinc supplementation of 10 mg/day in children with diarrhea in developing countries shortened the duration of diarrhea and reduced mortality. In Poland and countries with good food availability – the indication is different: only confirmed deficiency (zinc in serum <70 µg/dl) or acute illness episode in the at-risk group. Doses for children: 5–8 mg/day (children 1–8 years), 9–11 mg/day (9–13 years). Exceeding 25 mg/day long-term disrupts copper absorption.

Magnesium in children rarely requires supplementation with a proper diet rich in vegetables, nuts, and whole grains. Exceptions: children with ADHD (studies suggest lower magnesium levels in this group, Kozielec & Starobrat-Hermelin 1997), children with frequent muscle cramps, tension-related headaches, or children consuming a lot of processed food. Doses: magnesium glycinate or citrate – 100–200 mg of elemental Mg/day for children 6–12 years, 200–300 mg for teenagers. The glycinate form is gentle on the intestines – important because magnesium oxide and sulfate can cause diarrhea.

Vitamin B12 in children – when is it important, when is it essential?

Vitamin B12 is essential for DNA synthesis, nerve myelination, and red blood cell production. In children eating animal products (meat, fish, eggs, dairy), B12 deficiency is rare. However, in children on a vegan and strict vegetarian diet, B12 deficiency is a real risk – particularly dangerous, as neurological symptoms can develop slowly over months without clear clinical symptoms. Undiagnosed B12 deficiency in a child can lead to permanent neurological damage (demyelination) and developmental delays.

Children on a vegan diet should supplement B12 without exception. Doses: children 1–3 years – 10–50 µg/day of cyanocobalamin or 250 µg every 2–3 days; 4–10 years – 25–100 µg/day; 11–18 years – 50–250 µg/day. The methylcobalamin or hydroxocobalamin form is better tolerated by some children with methyl metabolism issues. Monitoring: serum B12 level (>300 pmol/l) and homocysteine every 6–12 months on a vegan diet.

Our observations: More and more families in Poland are transitioning to a vegan or vegetarian diet – which is their right and can be healthy with proper planning. However, we see that B12 and DHA are consistently underestimated in this group, while parents focus on iron and calcium. A vegan diet for a child requires a thoughtful supplementation plan approved by a pediatrician or a dietitian specializing in plant-based nutrition – just vegetables are not enough.

How to talk to a pediatrician about supplements for your child?

The pediatrician is the first and most important person to talk to about your child's supplementation. It is worth preparing for this conversation to make it effective. Questions to ask: What is the current level of vitamin D3 in the child? Do the blood test results indicate a deficiency of iron or B12? Does the child's diet meet the needs for DHA, zinc, and magnesium? What probiotic strains do you recommend for our child?

A pediatrician may order diagnostic tests (morphology, ferritin, 25(OH)D3), which provide an objective answer to the question of what the child actually needs. Supplementation without diagnostics is like shooting in the dark and often an unnecessary expense. The principle: one supplement justified by need is better than five "for safety" without indications. Children with a proper, varied diet, regular outdoor activity in summer, and without chronic diseases may not need any supplements other than vitamin D3 in winter.

Frequently Asked Questions

Below are answers to questions most frequently asked by parents regarding children's supplementation.

What dose of vitamin D3 should be given to a child?

The Polish Pediatric Society recommends: 0–6 months – 400 IU/day; 6–12 months – 400–600 IU/day; 1–10 years – 600–1000 IU/day (September–April or all year with no sun exposure); 11–18 years – 800–2000 IU/day. Goal: level of 25(OH)D3 30–50 ng/ml in the blood. As much as 90% of children in Poland have a deficiency in winter (Płudowski et al., 2021).

Is omega-3 safe for children?

DHA omega-3 is safe and recommended from infancy – essential for brain and retina development. Children 1–3 years: 100–150 mg DHA/day; 4–18 years: 200–500 mg EPA+DHA daily. No documented adverse effects at recommended doses. Form for children: flavored drops or omega-3 gummies.

Is melatonin safe for children?

Melatonin is not recommended for children under 12 without a doctor's indication. There is a lack of long-term safety studies, and there may be an impact on the hormonal axis during puberty. In children with sleep disorders – the first line is sleep hygiene and screen time reduction, not melatonin. With ASD and ADHD – only after consultation with a pediatrician.

When does a child need iron from a supplement?

Iron is supplemented only in confirmed deficiency: ferritin <12 µg/l or hemoglobin <110 g/l (children 1–5 years). Routine iron administration without deficiency disrupts zinc and copper absorption. At-risk groups: premature infants, vegan diet, Crohn's disease, celiac disease. Dosage only under pediatric supervision.

What supplements should be absolutely avoided in children?

Absolutely avoid: adaptogens (ashwagandha, ginseng, rhodiola, maca) – lack of safety data in children, impact on hormones; melatonin below 12 years of age without indication; vitamin A retinol >2500 IU/day in children under 9 years; supplements with caffeine, guarana, or taurine under 12 years; weight loss and stimulating supplements.

Are probiotics safe for children?

Lactobacillus rhamnosus GG and Saccharomyces boulardii are safe and well-studied in children over 1 year old. LGG shortens infectious diarrhea by 1–1.5 days; S. boulardii reduces antibiotic-associated diarrhea by 52% (Szajewska et al., 2015). In preterm infants and children with severe immune deficiencies – only after consultation with a pediatrician.

This article is for informational and educational purposes and does not constitute medical advice. Before starting to use cannabis or CBD for therapeutic purposes, consult a doctor, especially if you are taking other medications, are pregnant, or breastfeeding.

Author: Michał Waluk · Published: 2026-05-04 · Updated: 2026-05-04