Vitamins

Vitamin A

Vitamin A is a fat-soluble and essential nutrient crucial for your child's overall health and growth. It is vital for vision, immune function, and cellular development. Vitamin A is a powerful micronutrient that supports many critical processes in the body. It belongs to a group of compounds called retinoids. Since the body cannot produce it on its own, children must obtain it through their diet. There are two main types of Vitamin A found in food. Preformed Vitamin A (Retinol) comes from animal sources (like liver, dairy, and eggs). This form is immediately ready-to-use by the body. The second type is Provitamin A (Beta-Carotene), which comes from plant sources (like carrots and sweet potatoes). This is a precursor that the body converts into Retinol only when needed, making it the safest form to consume in large quantities. For Preformed Vitamin A (Retinol), good sources include liver (in small amounts), eggs, milk, and cheese. For Provitamin A (Beta-Carotene), focus on brightly colored foods like carrots, sweet potatoes, spinach, squash, kale and fruits such as mango. These orange, yellow, and dark green foods are easily converted by the body.

Vision:
Vitamin A is famously essential for vision. It is crucial for visual perception, particularly in the rods of the eye, which allow us to see in low light or at night.
Barrier protection:
Vitamin A is the guardian of your body's surfaces. It maintains the functional and structural integrity of epithelial tissues, acting like a continuous maintenance crew for the linings of your skin, eyes, and the internal tracts of your respiratory and gastrointestinal systems. This also includes supporting the production of protective substances like mucins in the gut.
Immunity:
Vitamin A is a critical factor in the body's defense forces, particularly the adaptive immune system—the part that learns to fight specific threats. It is necessary for the proper proliferation and differentiation of regulatory T cells, which manage the immune response.
Metabolism:
Vitamin A plays a background but vital role in metabolism, influencing how the body handles fats and helping to maintain healthy insulin sensitivity.

The EFSA recommends different daily values depending on the children's age. However, in kids supplements many European countries do not allow more than 200 µg RE/day. Take into consideration that RE is defined as: 1 µg RE = 1 µg of retinol = 6 µg of β-carotene = 12 µg of other carotenoids with provitamin A activity.

Vitamin A deficiency is more prevalent worldwide than retinoid intoxication. The most characteristic consequence of vitamin A deficiency is impaired vision. Early sight impairment is significant, especially under conditions of reduced light. A sudden excessive consumption of vitamin A leads to acute poisoning. The main symptoms observed in acute toxicity are nausea, irritability, reduced appetite, vomiting, blurry vision, headaches, hair loss, muscle pain, papilledema, hemorrhage, weakness, drowsiness and altered mental status.

β-carotene

- Carazo, A., Macáková, K., Matoušová, K., Krčmová, L. K., Protti, M., & Mladěnka, P. (2021). Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity. Nutrients, 13(5), 1703. https://doi.org/10.3390/nu13051703

- von Lintig, J. Metabolism of carotenoids and retinoids related to vision. J. Biol. Chem. 2012, 287, 1627–1634.

- Zhong, M.; Kawaguchi, R.; Kassai, M.; Sun, H. Retina, retinol, retinal and the natural history of vitamin A as a light sensor. Nutrients 2012, 4, 2069–2096.

- Pino-Lagos K, Benson MJ, Noelle RJ. Retinoic acid in the immune system. Ann N Y Acad Sci. 2008 Nov;1143:170-87. doi: 10.1196/annals.1443.017. PMID: 19076350; PMCID: PMC3826166.

- Iwata, M.; Hirakiyama, A.; Eshima, Y.; Kagechika, H.; Kato, C.; Song, S.Y. Retinoic acid imprints gut-homing specificity on T cells. Immunity 2004, 21, 527–538.

Vitamin C

Vitamin C, or ascorbic acid, is an essential, water-soluble vitamin that, while popular for its antioxidant function, has a much wider physiological role in the body. Unlike most mammals, humans lack the enzyme needed to synthesize it, so we rely entirely on dietary intake. Vitamin C is found in cells in millimolar concentrations, much higher than in blood circulation.

Antioxidant:
Vitamin C's primary function is to neutralize free radicals to combat oxidative stress and prevent cellular damage.
Mineral absorption:
As a consequence of its antioxidant properties, Vitamin C contributes to the reduction of iron, thereby facilitating its absorption. For example, consuming Vitamin C sources with ferric vegetable sources is a good strategy to prevent anemia.
Enzymatic Function and Synthesis:
Vitamin C is an essential cofactor for many enzymes. It is fundamental for the synthesis of hormones and carnitine, and crucial for the correct formation of connective tissue (e.g., collagen).
Cellular Regulation:
Vitamin C plays a critical role in epigenetic processes by acting as a cofactor for enzymes that regulate gene expression.

Daily intake recommendations vary substantially by age. In children the recommended dose varies from 30 to 100 mg/day.

Deficiency:
Vitamin C deficiency is rare. However, chronic deficiency of vitamin C is responsible for scurvy. Typical symptoms of scurvy include muscle weakness, swollen and bleeding gums, loss of teeth, petechial hemorrhaging, spontaneous ecchymoses, anemia, impaired wound healing, hyperkeratosis, weakness, myalgia, arthralgia, and weight loss (there can also be a paradoxical weight increase due to swelling), while early manifestations include lethargy, lassitude, and irritability.

Overdose:
Vitamin C is generally considered relatively safe. However, the administration of very high doses should be done with caution, as it can cause side effects in susceptible patients, such as the formation of kidney stones.

L-ascorbyl 6-palmitate

Doseděl, M., Jirkovský, E., Macáková, K., Krčmová, L. K., Javorská, L., Pourová, J., Mercolini, L., Remião, F., Nováková, L., Mladěnka, P., & on behalf of The OEMONOM. (2021). Vitamin C—Sources, physiological role, kinetics, deficiency, use, toxicity, and determination. Nutrients, 13(2), 615.

Carr, A. C., & Maggini, S. (2017). Vitamin C and immune function. Nutrients, 9(11), 1211.

Manning, J., Mitchell, B., Appadurai, D. A., Shakya, A., Pierce, L. J., Wang, H., & Spangrude, G. J. (2013). Vitamin C promotes maturation of T-cells. Antioxidants & Redox Signaling, 19(17), 2054–2067.

Vitamin D

Vitamin D, often called the “sunshine vitamin”, is an essential, fat-soluble nutrient crucial for numerous biological and physiological human processes. The body gets Vitamin D in two main ways. Vitamin D (Cholecalciferol) is produced in the skin from a precursor molecule under the influence of sunlight (UV). Both Vitamin D2 and D3 can be present in the diet. Once absorbed or produced, Vitamin D2 and D3 are first converted in the liver to 25-hydroxyvitamin D, which is the accepted biomarker of vitamin D status. The main source of Vitamin D for humans is non-enzymatic production in the skin via exposure to sunlight. Dietary sources include foods that contain: Vitamin D3 (Cholecalciferol), often found in animal products and fortified foods; and Vitamin D2 (Ergocalciferol), often found in plant sources.

Skeletal Health:
Vitamin D is essential for calcium homeostasis; deficiency reduces intestinal calcium absorption. Supplementation with Vitamin D and calcium together has been shown to decrease hip and other fractures in older adults.
Gene Regulation:
The active form acts as a hormone, regulating gene expression to support fundamental processes like cell growth and differentiation.
Immunity:
It is vital for the immune system, major trials suggesting benefits in reducing the incidence of autoimmune diseases. Deficiency increases the risks of both autoimmune and infectious diseases.
Cardiovascular and Metabolic Health:
Observational studies suggest potential benefits in reducing cardiovascular events and risks associated with the development of Type 2 Diabetes Mellitus (T2D).
Extra-Skeletal Development:
It is vital for numerous extra-renal tissues, including support for prenatal health, brain function, and positive effects on pregnancy and birth outcomes.

Vitamin D daily intake for kids triplicates the dose recommended for adults. The dose is 15 µg per day.

Deficiency:
Vitamin D deficiency remains a significant global public health issue, and it is estimated to affect about 42% of healthy children. Lack of Vitamin D results in impaired calcium absorption and increases susceptibility to and severity of infectious diseases.

Overdose:
Vitamin D overdose is rare, as deficiency is more prevalent than poisoning. It mainly causes hypercalcemia. Symptoms may include difficulty concentrating, confusion, apathy, drowsiness, depression, psychosis, and in extreme cases, stupor and coma. Additionally, vomiting, abdominal pain, polydipsia, anorexia, constipation, peptic ulcers, and pancreatitis may occur.

Ergocalciferol

Cui, A., Zhang, T., Xiao, P., Fan, Z., Wang, H., & Zhuang, Y. (2023). Global and regional prevalence of vitamin D deficiency in population-based studies from 2000 to 2022: A pooled analysis of 7.9 million participants. Frontiers in Nutrition, 10, 1070808.

Wimalawansa, S. J. (2023). Physiological basis for using vitamin D to improve health. Biomedicines, 11(6), 1542.

Disphanurat, W., Viarasilpa, W., Chakkavittumrong, P., & Pongcharoen, P. (2019). The clinical effect of oral vitamin D2 supplementation on psoriasis: A double-blind, randomized, placebo-controlled study. Dermatology Research and Practice, 2019(1), 5237642.

Giustina, A., Bilezikian, J. P., Adler, R. A., Banfi, G., Bikle, D. D., Binkley, N. C., … Virtanen, J. K. (2024). Consensus statement on vitamin D status assessment and supplementation: Whys, whens, and hows. Endocrine Reviews, 45(5), 625–654.

Vitamin B1

Vitamin B1, or Thiamine, is an essential water-soluble B-complex vitamin necessary for proper cell function and actively participates in the metabolism of carbohydrates, fats, and proteins. Thiamine exists in the body in various forms (free thiamine, mono-, di-, or triphosphate), with thiamine pyrophosphate (TPP) being the major active coenzyme form. The need for thiamine increases when the diet contains a high proportion of carbohydrates, reflecting its critical role in glucose processing. Thiamine cannot be produced by the body and must be acquired through diet. It is found naturally in a wide variety of plant and animal foods. Since grain processing often removes much of the vitamin content, many flours, cereals, and infant formulas in developed countries are fortified with thiamine. Animal sources: pork (lean cuts and products), trout, salmon, mussels, and organ meats (such as liver). Plant sources: whole grains (brown rice, whole wheat bread), legumes (black beans, lentils, peas, soybeans), nuts (pecans, macadamia), seeds (especially sunflower seeds), and yeast (including nutritional yeast and yeast extract spreads).

Energy and Cellular Metabolism:
Thiamine is required for the proper functioning of enzymes involved in glucose metabolism, making it critical for providing energy to all cells. It participates in cellular respiration, the oxidation of fatty acids, and the overall process of energy production.
Nervous System Function:
It is vital for ensuring the proper functioning of both the central and peripheral nervous systems. It is involved in the synthesis of important neurotransmitters, and its absence directly affects nerve and brain health.
Cellular Integrity and DNA Repair:
Thiamine is a prerequisite for the functioning of key enzymes involved in the biosynthesis of pentose sugars, which are essential for the synthesis of nucleic acids (DNA/RNA). Additionally, Thiamine has antioxidant properties that help reduce oxidative stress, indirectly supporting the maintenance of DNA integrity and repair mechanisms.

The European Food Safety Authority (EFSA) recommends that children receive 0.1 mg of thiamin per Megajoule (MJ) of energy consumed. This value is used because thiamin's requirement is closely linked to the body's energy metabolism. To find your child's specific daily need in milligrams (mg/day), you must multiply the 0.1 mg/MJ value by their total daily energy intake in MJ. For example, a moderately active child aged 4–6 with an average energy need of about 6 MJ would require approximately 0.6 mg of thiamin per day.

Deficiency:
Thiamine deficiency, known as beriberi, remains a risk in populations with limited diets (e.g., those relying heavily on polished white rice) and in specific risk groups such as individuals with disease-related malnutrition and a predisposition to malabsorption.

Overdose:
Since Vitamin B1 is water-soluble, excess amounts are readily excreted in the urine. For this reason, oral thiamine intake is considered relatively safe, and no Tolerable Upper Intake Level has been established for Vitamin B1.

Thiamine pyrophosphate chloride

Mrowicka, M., Mrowicki, J., Dragan, G., & Majsterek, I. (2023). The importance of thiamine (vitamin B1) in humans. Bioscience Reports, 43(10), BSR20230374.

Kaźmierczak-Barańska, J., Halczuk, K., & Karwowski, B. T. (2025). Thiamine (vitamin B1)—An essential health regulator. Nutrients, 17(13), 2206.

Nga, N. T. T., & Quang, D. D. (2019). Unraveling the antioxidant potential of thiamine: Thermochemical and kinetics studies in aqueous phase using DFT. Vietnam Journal of Chemistry, 57(4), 485–490.

Vitamin B2

Vitamin B2, or Riboflavin (RF), is an essential water-soluble B-complex vitamin. It is a fundamental component of the human diet, necessary for key metabolic functions and cellular protection. The body cannot synthesize it and must obtain it from dietary sources. Riboflavin is relatively stable to heat but is highly photosensitive (easily destroyed by exposure to light, which is why milk is often sold in opaque containers). Riboflavin is widely available in both plant and animal foods. Animal sources: milk and dairy products (cheese). Plant sources: green leafy vegetables, mushrooms, almonds, nuts, rice, and legumes.

Energy and Cellular Metabolism:
Vitamin B2 is an essential cofactor for many metabolic reactions in the body. These reactions form the basis of carbohydrate, protein, and fat metabolism and are critical for cellular respiration and overall energy production.
Antioxidant and Protective Function:
Riboflavin protects the body against oxidative stress, particularly lipid peroxidation and reperfusion oxidative injury (damage caused by the restoration of blood flow after a period of ischemia).
Other clinical benefits:
Vitamin B2 also contributes to eye health and cognitive function.

Daily intake recommendations vary substantially by age. In children the recommended dose varies from 0.6 to 1.1 mg/day.

Deficiency:
Riboflavin deficiency is linked to an increased risk of anemia due to impaired iron absorption, metabolism of tryptophan, mitochondrial function, brain function, and the metabolism of other vitamins.

Overdose:
Riboflavin has no known toxicity, even at very high doses, because the body's absorption capacity is limited and excess amounts are rapidly excreted in the urine. For this reason, no Tolerable Upper Intake Level has been established.

Riboflavin 5’-phosphate, sodium

Suwannasom, N., Kao, I., Pruß, A., Georgieva, R., & Bäumler, H. (2020). Riboflavin: The health benefits of a forgotten natural vitamin. International Journal of Molecular Sciences, 21(3), 950.

Ashoori, M., & Saedisomeolia, A. (2014). Riboflavin (vitamin B2) and oxidative stress: A review. British Journal of Nutrition, 111(11), 1985–1991.

Cheung, I. M., McGhee, C. N., & Sherwin, T. (2014). Beneficial effect of the antioxidant riboflavin on gene expression of extracellular matrix elements, antioxidants and oxidases in keratoconic stromal cells. Clinical and Experimental Optometry, 97(4), 303–309.

Vitamin B3

Vitamin B3, or Niacin, is an essential water-soluble B-complex vitamin that encompasses two primary forms found in food and supplements: Nicotinic Acid and Nicotinamide (Niacinamide). Unlike most vitamins, niacin can be partially synthesized by the body from the amino acid tryptophan (found in protein-rich foods). Despite this, adequate dietary intake of niacin itself is essential to meet the body's needs. Animal sources: red meats, poultry and fish. Plant sources: brown rice, nuts, legumes (e.g., peanuts), and seeds.

Energy and Cellular Metabolism:
Niacin functions as a coenzyme in over 400 reactions, more than any other vitamin-derived coenzyme. Its primary role is as a precursor of two essential coenzymes: Nicotinamide Adenine Dinucleotide (NAD) and Nicotinamide Adenine Dinucleotide Phosphate (NADP). Both molecules are involved in the body’s metabolism and energy production.
DNA Repair and Cellular Integrity:
NAD is required for enzymes involved in critical cellular functions, including the maintenance of genome integrity and DNA repair mechanisms. A sufficient supply of niacin is essential for healthy cell function and regeneration.
Nervous and Digestive System Function:
Niacin is necessary to maintain a healthy nervous system, contributing to normal psychological function and the formation of neurotransmitters. It is also vital for the normal function of the digestive system and mucous membranes.

The recommended daily intake is expressed in Niacin Equivalents (NE)/ megajoule (MJ), where 1NE = 1 mg of Niacin or 60 mg of Tryptophan. a moderately active child aged 4-6 with an average energy need of about 6 MJ would require approximately 8 mg of niacin per day.

Deficiency:
Severe niacin and/or Trp deficiency leads to a variety of clinical symptoms, including diarrhea, dermatitis, and dementia, collectively known as “pellagra” or “the three D disease”. Niacin is present in many foods, making deficiency rare in developed countries.

Overdose:
Niacin overdose (around 3 grams per day) can cause serious hepatotoxicity that ranges from a mild elevation of liver enzymes to acute liver failure. Clinical manifestations include fatigue, nausea, and vomiting.

Inositol hexanicotinate

Hrubša, M., Siatka, T., Nejmanová, I., Vopršalová, M., Kujovská Krčmová, L., Matoušová, K.,Oemonom. (2022). Biological properties of vitamins of the B-complex, part 1: Vitamins B1, B2, B3, and B5. Nutrients, 14(3), 484.

Gasperi, V., Sibilano, M., Savini, I., & Catani, M. V. (2019). Niacin in the central nervous system: An update of biological aspects and clinical applications. International Journal of Molecular Sciences, 20(4), 974.

Vitamin B5

Vitamin B5, or Pantothenic Acid, is a water-soluble vitamin essential for metabolism. The name comes from the Greek word "panthos," meaning "everywhere," which reflects its ubiquitous presence in food. It is widespread in food, making deficiency rare. Rich sources include: Animal sources: meat, eggs, milk, cheese and royal jelly (one of the richest natural sources). Plant sources: whole grain cereals, legumes, nuts, yeast, mushrooms, avocado, potatoes, and cruciferous vegetables (broccoli, cauliflower). Note on Processing: Milling of cereals can reduce content by 50–88%. While pantothenic acid is stable to heat at optimal pH levels, significant losses (15–50% in meat/fish) can occur through leaching into cooking liquids, particularly during boiling.

Vitamin B5 actively participates in numerous catabolic (energy-releasing) and anabolic (biosynthesis) reactions. It is crucial in the synthesis of fatty acids, cholesterol, steroid hormones, acetylcholine (a key neurotransmitter), and bile acids.

In children the daily recommended dose is 4–5 mg.

Deficiency:
Vitamin B5 deficiency is generally rare and usually occurs alongside multiple nutrient deficiencies in cases of severe malnutrition. Common symptoms include fatigue, irritability, sleep disturbances, and gastrointestinal issues.

Overdose:
No Tolerable Upper Intake Level has been established for pantothenic acid because there are no reports of adverse effects from food or supplements at normal levels. Very high doses may cause mild gastrointestinal upset and diarrhea.

Pantethine

Yoshii, K., Hosomi, K., Sawane, K., & Kunisawa, J. (2019). Metabolism of dietary and microbial vitamin B family in the regulation of host immunity. Frontiers in Nutrition, 6, 434971.

Hrubša, M., Siatka, T., Nejmanová, I., Vopršalová, M., Kujovská Krčmová, L., Matoušová, K., Javorská, L., Macáková, K., Mercolini, L., Remião, F., Máťuš, M., Mladěnka, P., & on behalf of the OEMONOM. (2022). Biological properties of vitamins of the B-complex, part 1: Vitamins B1, B2, B3, and B5. Nutrients, 14(3), 484.

Vitamin B6

Vitamin B6 is a water-soluble B-vitamin, also known as Pyridoxine. As a water-soluble vitamin, the body does not store large amounts, so a regular dietary intake is necessary. Key sources of Vitamin B6 include: Animal Sources: beef liver, tuna, salmon, and poultry. Plant Sources: chickpeas, potatoes (and other starchy vegetables), fortified cereals, and bananas. Vitamin B6 is heat stable, and processing steps such as cooking or frying do not significantly affect its content.

Metabolism:
Vitamin B6 is essential for over 100 enzyme reactions, primarily involved in protein metabolism. It participates in the breakdown of proteins, as well as fats and carbohydrates, turning them into usable energy.
Brain and nerve function:
Pyridoxine is crucial for brain development and function, including the production of neurotransmitters like serotonin (which regulates mood) and norepinephrine (which helps the body respond to stress).
Red blood cell formation:
Vitamin B6 is necessary for the creation of red blood cells and for maintaining normal levels of the amino acid homocysteine, which, when elevated, is linked to an increased risk of heart disease.

For children, the EFSA recommended dose is between 0.6 mg and 0.9 mg per day.

Deficiency:
Vitamin B6 deficiency is uncommon but can occur alongside deficiencies in other B-vitamins. Symptoms may include microcytic anemia, seborrheic dermatitis, confusion, and weakened immune function.

Overdose:
Vitamin B6 overdose can affect the nervous system, causing burning and tingling sensations that may lead to peripheral neuropathy.

Pyridoxal 5’-phosphate

Stach, K., Stach, W., & Augoff, K. (2021). Vitamin B6 in health and disease. Nutrients, 13(9), 3229.

Mooney, S., Leuendorf, J.-E., Hendrickson, C., & Hellmann, H. (2009). Vitamin B6: A long known compound of surprising complexity. Molecules, 14(1), 329–351.

Parra, M., Stahl, S., & Hellmann, H. (2018). Vitamin B₆ and its role in cell metabolism and physiology. Cells, 7(7), 84.

Vitamin B12

Vitamin B12, also known as Cobalamin, is a water-soluble vitamin essential for human health. A healthy gut normally absorbs about 50% of the total intake of vitamin B12. It is naturally found almost exclusively in animal-source foods; however, many foods are fortified with added vitamin B12 to reduce the risk of deficiency in vegan and vegetarian populations. Food processing techniques that can contribute to dietary B12 degradation include pasteurization, heating, canning, and irradiation.

Nervous System Health:
Vitamin B12 is a critical cofactor for synthesizing myelin (the protective sheath around nerve fibers) and neurotransmitters, ensuring the proper functioning of the central and peripheral nervous systems.

Metabolism:
It participates in cellular metabolism and is essential for regulating homocysteine levels. Low B12 levels are associated with elevated homocysteine, which is a risk factor for cognitive impairment and depression.

The EFSA recommendations for vitamin B12 daily intake for kids are 1.5–2.5 µg per day.

Deficiency:
Vitamin B12 deficiency can cause fatigue or weakness. These are symptoms of megaloblastic anemia, which is a hallmark of vitamin B12 deficiency.

Overdose:
A Tolerable Upper Intake Level has not been established for vitamin B12, as there is a low risk of adverse effects from food or supplements in healthy individuals. The body's absorption capacity is limited, and excess amounts are rapidly excreted in the urine.

5’-deoxyadenosylcobalamin

Abuyaman, O., Abdelfattah, A., Shehadeh-Tout, F., Deeb, A. A., & Hatmal, M. M. (2023). Vitamin B12 insufficiency and deficiency: A review of nondisease risk factors. Scandinavian Journal of Clinical and Laboratory Investigation, 83(8), 533–539.

Markun, S., Gravestock, I., Jäger, L., Rosemann, T., Pichierri, G., & Burgstaller, J. M. (2021). Effects of vitamin B12 supplementation on cognitive function, depressive symptoms, and fatigue: A systematic review, meta-analysis, and meta-regression. Nutrients, 13(3), 923.

Folic Acid

Folic acid is the synthetic (human-made) form of the naturally occurring vitamin, Folate (also known as Vitamin B9). It is a water-soluble B-vitamin that plays a fundamental role in cell division and growth. The body cannot produce folate on its own, so children and adults must obtain it through their diet. Folic acid, the synthetic form, is better absorbed by the body than the natural folate found in food (up to 85% absorption vs. approximately 50%, respectively). This high bioavailability is why many countries require folic acid fortification in staple grain products like enriched breads, flours, cereals, pastas, and rice. Folic acid is found in plant and animal sources. Plant sources: spinach, kale, and collard greens, citrus fruits, peas, lentils. Animal sources: liver.

Growth and cell division:
Folate is critical during periods of rapid growth and cell division, making it especially vital for infants and children. It functions as a coenzyme in single-carbon transfers, which are essential for the body's internal chemistry. One of its most crucial functions is the synthesis and repair of genetic material, necessary for all cell creation and replication.
DNA and RNA Synthesis:
Folate is indispensable for building DNA, the body's genetic blueprint. This makes it vital for the development of the fetus, infants, and children.
Red Blood Cell Formation:
Folate is necessary to produce healthy red blood cells, which carry oxygen throughout the body.
Protein Metabolism:
It works closely with Vitamin B12 to regulate the breakdown and use of proteins, playing a key role in converting the amino acid homocysteine into methionine. High homocysteine levels are linked to cardiovascular disease risk.
Brain and Nervous System Development:
Adequate folate intake is vital for brain growth and function, supporting the central nervous system and affecting mood and cognitive function in children.

The daily recommended dose of biotin for kids is between 110 and 160 µg per day.

Deficiency:
Folate deficiency can occur due to poor diet, malabsorption issues (like celiac disease), or certain medications. Because folate is essential for cell division, a deficiency primarily impacts rapidly dividing cells (blood cells and cells lining the gut). A lack of folate leads to megaloblastic anemia, diarrhea, loss of appetite, poor growth, and developmental delays.

Overdose:
A Tolerable Upper Intake Level (UL) has been established at 300–600 µg per day for folic acid (the synthetic form) from fortified foods and supplements. There is no UL set for folate that occurs naturally in food, as there is no evidence of adverse effects from consuming natural food sources. The concern with excessive folic acid intake is that it can mask a vitamin B12 deficiency. High-dose folic acid may correct the anemia caused by a B12 deficiency.

Pteroylmonoglutamic acid

Panda, P. K., Sharawat, I. K., Saha, S., Gupta, D., Palayullakandi, A., & Meena, K. (2024). Efficacy of oral folinic acid supplementation in children with autism spectrum disorder: A randomized double-blind, placebo-controlled trial. European Journal of Pediatrics, 183(11), 4827–4835.

Zhang, S., Yang, M., Hao, X., Zhang, F., Zhou, J., Tao, F., & Huang, K. (2023). Peri-conceptional folic acid supplementation and children's physical development: A birth cohort study. Nutrients, 15(6), 1423.

Williams, B. A., McCartney, H., Singer, J., Devlin, A. M., Vercauteren, S., Amid, A., Wu, J. K., & Karakochuk, C. D. (2025). Folic acid supplementation in children with sickle cell disease: A randomized double-blind noninferiority cross-over trial. American Journal of Clinical Nutrition, 121(4), 910–920.

Vitamin K1

Vitamin K1, chemically known as phylloquinone (or phytomenadione/phytonadione), is the natural plant form of Vitamin K. It is a fat-soluble vitamin essential for the human body. K1 is the predominant form of Vitamin K in the human diet, making up approximately 75–90% of total intake. However, its bioavailability is low. In addition, vitamin K1 is extremely sensitive to daylight and fluorescent light. The primary sources of vitamin K1 are green leafy vegetables including kale, spinach, chard, parsley, broccoli, and Brussels sprouts.

Blood coagulation:
Vitamin K is traditionally associated with its role in the blood coagulation cascade. It is required for the posttranslational modification of seven proteins involved in this cascade.
Tissue calcification:
Vitamin K1 participates in the calcification of connective tissue, which is physiologically necessary in bones. As a consequence of both functions, it is directly related to cardiovascular health.

Daily intake recommendations vary by age. In children the recommended dose varies from 20 to 30 µg/day.

Deficiency:
Deficiency is rare in healthy children and adults, as it is widely available in food. Newborns and children suffering from intestinal diseases are more likely to develop vitamin K1 deficiency due to absorption problems. The primary symptom is uncontrolled bleeding (hemorrhage) due to impaired blood clotting.

Toxicity:
For vitamin K1 derived from food or supplements, no Tolerable Upper Intake Level has been established. This means that, based on current evidence, high intakes of vitamin K1 are not known to cause adverse health effects.

Menaquinone

Tsugawa, N., & Shiraki, M. (2020). Vitamin K nutrition and bone health. Nutrients, 12(7), 1909.

Booth, L. S.(2012). Vitamin K: food composition and dietary intakes. Food & nutrition research, 56(1), 5505.

Mladěnka, P., Macáková, K., Kujovská Krčmová, L., Javorská, L., Mrštná, K., Carazo, A., Protti, M., Remião, F., Nováková, L., & OEMONOM researchers and collaborators. (2022). Vitamin K—Sources, physiological role, kinetics, deficiency, detection, therapeutic use, and toxicity. Nutrition Reviews, 80(4), 677–698.

Vitamin E

Vitamin E is a lipid-soluble vitamin and a widely popular dietary supplement for overall health. It is one of the major components of the cell's antioxidant defense system and is exclusively obtained from the diet. Vitamin E is a general term that encompasses eight different fat-soluble compounds of plant origin. These compounds are divided into two groups, each with four variations: tocopherols and tocotrienols. The primary and most active form of Vitamin E in the human body is α-tocopherol. Vitamin E is commonly found in plant sources such as leafy vegetables, whole grains, nuts, seeds, vegetable oils (like olive oil), and avocados.

Antioxidant Defense:
As a well-known antioxidant, α-tocopherol protects cells from oxidative stress and damage caused by free radicals.
Cellular Integrity and Immunity:
It is essential for maintaining cellular integrity and supporting immune function.
Blood Health:
Vitamin E may prevent platelet hyperaggregation, which is linked to atherosclerosis. It does this by helping to reduce the production of prostaglandins like thromboxane, which cause platelets to clump.
Regulation:
α-tocopherols are also involved in other processes such as cell signaling and gene expression.

In children the recommended daily dose is 9 mg/day.

Deficiency:
Symptomatic deficiency is rare but can occur. It can result from an acquired or inherited condition that impairs its absorption. The classic clinical sign of deficiency is neurological dysfunction and vision alterations.

Overdose:
Vitamin E has a relatively low level of toxicity, but high doses of supplements pose potential risks. Toxicity can manifest as interference with other fat-soluble vitamins, specifically Vitamin K's action, which can lead to severe bleeding issues. High-dose Vitamin E can also act as a pro-oxidant under certain conditions, particularly when the body does not sufficiently recycle it using other antioxidants like Vitamin C.

Tocotrienol tocopherol

Xiong, Z., Liu, L., Jian, Z., Ma, Y., Li, H., Jin, X., Liao, B., & Wang, K. (2023). Vitamin E and multiple health outcomes: An umbrella review of meta-analyses. Nutrients, 15(15), 3301.

Shahidi, F., Pinaffi-Langley, A. C. C., Fuentes, J., Speisky, H., & de Camargo, A. C. (2021). Vitamin E as an essential micronutrient for human health: Common, novel, and unexplored dietary sources. Free Radical Biology and Medicine, 176, 312–321.

Kaye, A. D., Thomassen, A. S., Mashaw, S. A., MacDonald, E. M., Waguespack, A., Hickey, L., & Hickey, L. C. (2025). Vitamin E (α-tocopherol): Emerging clinical role and adverse risks of supplementation in adults. Cureus, 17(2), e78679.

Biotin

Biotin, also known as Vitamin B7 (or sometimes Vitamin H), is a water-soluble B-vitamin essential for human health and a powerful micronutrient that supports numerous fundamental metabolic processes. Since the body cannot synthesize it on its own, it must be obtained through the diet. Biotin is found in a wide variety of foods, though generally at low concentrations. It is readily available in both animal and plant-based sources. Key foods include: Animal sources: liver, egg yolk, and milk. Plant sources: whole-grain cereals, soy, nuts, avocados, and seeds.

Gluconeogenesis and fatty acid synthesis:
One of its most crucial functions is its role as a coenzyme for carboxylase enzymes. These enzymes are key metabolic switch points and help convert non-carbohydrate sources (like amino acids) into glucose, the primary fuel for the body and brain. Biotin also contributes to the synthesis of fatty acids needed by the body.
Amino acid catabolism:
Biotin assists in the breakdown of branched-chain amino acids, which are fundamental building blocks of proteins.
Hair, skin and nails:
Biotin supports the structure of keratin, a fundamental protein that makes up hair, skin and nail tissues.
Nervous system:
It is required for the proper functioning of the central and peripheral nervous systems. High-dose biotin is being studied for its potential role in some progressive neurological diseases.

The daily recommended dose of biotin for kids is 25 µg per day.

Deficiency:
Biotin deficiency is rare in healthy individuals consuming a mixed diet. However, it can occur in individuals receiving long-term parenteral nutrition without supplementation, in those with the genetic disorder biotinidase deficiency, or due to prolonged consumption of raw egg whites (which contain avidin, a protein that binds biotin). The common symptoms of biotin deficiency are hair loss, conjunctivitis, and dermatitis.

Overdose:
A tolerable upper intake level has not been established for biotin due to a lack of evidence of adverse health effects from high doses in humans. Biotin is generally considered safe, even at high amounts.

D-biotin

Stokke Solvik, B., & Strand, T. A. (2024). Biotin: A scoping review for Nordic Nutrition Recommendations 2023. Food & Nutrition Research, 68.

Mock, D. M. (2017). Biotin: From nutrition to therapeutics. Journal of Nutrition, 147(8), 1487–1492.

Sakurai-Yageta, M., & Suzuki, Y. (2024). Molecular mechanisms of biotin in modulating inflammatory diseases. Nutrients, 16(15), 2444.