How do vitamins work? How much of each vitamin do you need?
What foods are rich in vitamins?
We’ve summarized the latest research to answer these questions.
Vitamin A
How vitamin A works:
- Involved in cell growth and development
- Necessary for fetal development
- Needed for vision and health of the cornea of the eye
- Supports immune function
- Essential for epithelial cell health (e.g., lines the esophagus, lungs, blood vessels)
How much vitamin A do you need each day?
| Group | Amount |
| 0 – 8 years | 300 – 500 micrograms, depending on age |
| 9 – 13 years | 600 micrograms |
| Males 14+ years | 900 micrograms (3000 IU) |
| Females 14+ years | 700 micrograms (~2,333 IU) |
| Pregnancy | 750 – 770 micrograms, depending on age |
| Breastfeeding | 1200 – 1300 micrograms, depending on age |
How much is too much vitamin A? More than 3 milligrams or 10,000 IU per day for adults
Foods rich in vitamin A:
- Sweet potatoes
- Dark leafy greens
- Carrots, pumpkin, and other orange fruits and veggies
- Liver, other animal organs, cod liver oil
- Egg yolks
- Fortified dairy
Notes:
- Beta-carotene and other orange/ yellow/ red carotenoid pigments found in plants can form vitamin A in the body.
- Beware, animal-sources of vitamin A (e.g., cod liver oil) and some supplements (retinyl compounds) can be toxic in high doses.
- Beta-carotene supplements at high doses may have negative health effects, especially for those at higher risk of lung cancer (e.g., smokers).
- Zinc deficiency may reduce the ability of vitamin A to be stored and transported in the body.
- Vitamin A deficiency may exacerbate iron deficiency anemia.
Vitamin B1 (Thiamin)
How vitamin B1 works:
- Essential for energy to be released from food to keep cells alive
- Part of numerous enzymes involved in glucose, amino acid, and lipid metabolism
- Involved in nervous system health
How much thiamin do you need each day?
| Group | Amount |
| 0 – 12 months | 0.2 – 0.3 mg, depending on age |
| 1 – 13 years | 0.5 – 0.9 mg, depending on age |
| 14+ years | 1 – 1.2 mg, depending on age and gender |
| Pregnancy and breastfeeding | 1.4 mg |
Foods rich in B1:
- Whole and fortified grain and cereal products (bread, pasta, rice)
- Pork, fish
- Beans, lentils
- OJ
Notes:
- Heating foods can reduce thiamin content.
- Thiamin can leach into water and is lost when cooking water is thrown out.
- Alcohol consumption may flush water-soluble nutrients, including thiamin, from the body.
Vitamin B2 (Riboflavin)
How vitamin B2 works:
- Involved in energy production
- Required for protein, fat, and carb metabolism
- Involved in red blood cell production
- Involved in growth and cell function
- Works with folate to create DNA
How much vitamin B2 do you need each day?
| Group | Amount |
| 0 – 12 months | 0.3 – 0.4 mg, depending on age |
| 1 – 13 years | 0.5 – 0.9 mg, depending on age |
| 14 years+ | 1.1 mg females, 1.3 mg males |
| Pregnancy | 1.4 mg |
| Breastfeeding | 1.6 mg |
Foods rich in vitamin B2:
- Whole grains, fortified grains, cereals
- Pork, dairy, organ meats, lamb
- Almonds, quinoa
Notes: Vitamin B2 is sensitive to UV light and can break down in sunlight.
Niacin (vitamin B3)
How niacin works:
- Required for energy production
- Needed for more than 400 enzymes in the body used for critical cell functions
- Involved in protein, carb, and fat metabolism
How much niacin do you need each day?
| Group | Amount |
| 0 – 12 months | 2 – 4 mg, depending on age |
| 1 – 8 years | 6 – 8 mg, depending on age |
| 9 – 13 years | 12 mg |
| 14+ years | 14 mg females, 16 mg males |
| Pregnancy | 18 mg |
| Breastfeeding | 17 mg |
How much is too much niacin? For adults, more than 35 mg a day from supplements may cause negative health effects.
Foods rich in niacin:
- Liver, poultry, fish, beef
- Cereals, legumes (peanuts, lentils)
- Fortified foods
- Yeast extract spread (vegemite)
Notes: The amino acid tryptophan can be converted to niacin in the body.
Folate
How folate works:
- Required for DNA production
- Participates with enzymes in the body required for the metabolism of many amino acids
- Low folate intake can reduce red blood cell formation, causing one type of anemia
- Folate is essential for fetal growth and development
How much folate do you need each day?
| Group | Amount |
| 0 – 12 months | 65 – 80 micrograms, depending on age |
| 1 – 13 years | 150 to 300 micrograms, depending on age |
| 14+ years | 400 micrograms |
| Pregnancy | 600 micrograms |
| Breastfeeding | 500 micrograms |
How much is too much folate?
For adults, folic acid supplements with greater than 1000 micrograms per day may cause negative effects.
Foods rich in folate:
- Vegemite (yeast extract spread)
- Whole and fortified grains and cereals
- Liver
- Legumes (beans, soy, lentils)
- Sunflower seeds
- Dark leafy greens
- Seaweed
Notes:
- It is essential for pregnant women or those trying to conceive to get enough folate since it may reduce the risk of birth defects.
- Alcohol interferes with folate absorption and increases losses.
- Some studies show folate and vitamin B6 may help protect against heart disease by lowering homocysteine levels in the blood (an amino acid believed to cause damage to the arteries when elevated).
- Folate requirements increase during pregnancy, recovery from burns, malabsorption, and increased water losses (e.g., Chron’s disease, alcoholism, and diarrhea).
Pantothenic Acid (B5)
How pantothenic acid works:
- Involved in energy production from food
- Makes and breaks down fats
- Part of Coenzyme-A used in essential biochemical reactions throughout the body
How much pantothenic acid do you need each day?
| Group | Amount |
| 0 – 12 months | 1.7 – 1.8 mg, depending on age |
| 1 – 13 years | 2 – 4 mg, depending on age |
| 14+ years | 5 mg |
| Pregnant | 6 mg |
| Breastfeeding | 7 mg |
Foods rich in pantothenic acid:
- Beef, chicken, fish, eggs, organ meats
- Whole grains
- Sunflower seeds
- Mushrooms
- Legumes (peanuts, peas, lentils)
- Avocados
- Chickpeas
Biotin
How biotin works:
- Essential for enzymes that produce and store energy for cells
- Supports the production of several amino acids
- Involved in regulating DNA expression
How much biotin do you need each day?
| Group | Amount |
| 0 – 12 months | 5 – 6 micrograms, depending on age |
| 1 – 8 years | 8 – 12 micrograms, depending on age |
| 9 – 18 years | 20 – 25 micrograms, depending on age |
| 19+ | 30 micrograms |
| Pregnancy | 30 micrograms |
| Breastfeeding | 35 micrograms |
Foods rich in biotin: Yeast, liver, eggs, meats, poultry, avocados
Notes: RAW egg white contains avidin, a compound that can trap biotin. However, avidin is broken down when eggs are cooked.
Vitamin B6
How vitamin B6 works:
- Involved in more than 100 enzymes throughout body
- Involved in protein, fat, and carbohydrate metabolism
- Supports immune system function (promotes lymphocyte and IL2 production)
- Involved in neurotransmitter formation
- Involved in hemoglobin formation
How much vitamin B6 do you need each day?
| Group | Amount |
| 0 – 12 months | 0.1– 0.3, depending on age |
| 1 – 13 years | 0.5 – 1 mg, depending on age |
| 14 – 50 years | 1.2 – 1.3 mg, depending on age and gender |
| 51+ years | 1.5 mg females, 1.7 mg males |
| Pregnant | 1.9mg |
| Breastfeeding | 2 mg |
How much B6 is too much? For adults, greater than 100 mg a day from supplements may cause negative health effects.
Foods rich in vitamin B6:
- Chickpeas
- Fish, beef poultry, organ meats
- Fortified cereals
- Mushrooms
- Sunflower seeds
- Potatoes
- Bananas
Vitamin B12
How vitamin B12 works:
- Supports DNA production
- Works with B vitamins to produce many amino acids and molecules that participate in energy pathways
- Supports myelin neurotransmitter production to maintain healthy nerves
- Supports folate re-utilization to help produce cells such as red blood cells
How much vitamin B12 do you need each day?
| Group | Amount |
| 0 – 12 months | 0.4– 0.5 micrograms, depending on age |
| 1 – 8 years | 0.9 – 1.2 micrograms, depending on age |
| 9 – 13 years | 1.8 micrograms |
| 14+ years | 2.4 micrograms |
| Pregnancy | 2.6 micrograms |
| Breastfeeding | 2.8 micrograms |
Foods rich in B12:
- Seafood, meats, poultry, liver
- Milk
- Eggs
- Some fermented beans and vegetables and edible algae and mushrooms
Notes:
- Older adults, those with chronic stomach inflammation, or heavy antacid users are at risk for B12 deficiency because foods with B12 need stomach acids, enzymes, and a protein secreted in the stomach to attach to it for absorption into the body.
- Plant foods typically do not contain sufficient B12. Thus, vegans and vegetarians are at higher risk for B12 deficiency. B12 deficiency can result in permanent nerve damage.
Vitamin C
How vitamin C works:
- Functions as an antioxidant
- Supports enzymes to regenerate vitamin E into its antioxidant form
- Needed for collagen formation for skin, bones, tissues, and cartilage
- Required for many proteins, many hormones and neurotransmitters (e.g., dopamine), and carnitine (used to burn fat)
- Supports the immune system and is thought to have an antihistamine effect
- May increase iron absorption from plant foods when eaten together
How much vitamin C do you need each day?
| Group | Amount |
| 0 – 12 months | 40 – 50 mg, depending on age |
| 1 – 8 years | 15 – 25 mg, depending on age |
| 9 – 13 years | 45 mg |
| 14 – 18 years | 65 mg females, 75mg males |
| 19+ years | 75 mg females, 90 mg males |
| Pregnancy | 80 – 85 mg, depending on age |
| Breastfeeding | 115 – 120 mg, depending on age |
| Smokers | Add 35mg to daily requirements |
How much is too much vitamin C? In adults, vitamin C intake of more than 2000 mg a day may have negative side effects.
Foods rich in vitamin C: Citrus (OJ, grapefruit), kale, kiwi, and cauliflower
Notes:
- Vitamin C may reduce the severity and duration of cold symptoms.
- Vitamin C intake may influence the amount of vitamin C in breastmilk.
Vitamin D
How vitamin D works:
- Involved in calcium balance in the body
- Promotes calcium absorption from the gut
- Supports bone health
- Supports immune function
- Involved in cell growth
How much vitamin D do you need each day?
| Group | Amount |
| 0 – 12 months | 10 micrograms (400 IU) |
| 1 – 70 years | 15 micrograms (600 IU) |
| 71+ years | 20 micrograms (800 IU) |
| Pregnancy and lactation | 15 micrograms (600 IU) |
How much is too much vitamin D? More than 100 micrograms (4000 IU) per day for adults may cause negative health effects.
Good sources of vitamin D:
- Sunlight
- Fortified milk
- Fatty fish (salmon, mackerel, sardines)
- Fortified OJ
- Mushrooms (UV light exposed)
Notes:
Although we can make vitamin D from sunlight, many people do not make enough vitamin D, especially if they live in higher latitudes (far north/south), spend much time indoors, or have darker skin.
Vitamin E
How vitamin E works:
- Provides antioxidant support
- Supports cell membranes
- Supports the immune system
How much vitamin E do you need each day?
| Group | Amount |
| 0 – 12 months | 4 – 5 mg, depending on age |
| 1 to 13 years | 6 – 11 mg, depending on age |
| 14+ years | 15 mg |
| Pregnancy | 15 mg |
| Breastfeeding | 19 mg |
How much is too much vitamin E? For adults, more than 1000 mg a day (1100-1500 IU depending on the form of vitamin E) may result in negative health effects.
Foods rich in vitamin E: Avocado, nuts, seeds, vegetable oils
Notes: The majority of Americans do not eat enough vitamin E.
Vitamin K
How vitamin K works:
- Involved in blood clotting
- Supports bone health
- Supports blood vessel health
How much vitamin K do you need each day?
| Group | Amount |
| 0 – 12 months | 2 – 2.5 micrograms, depending on age |
| 1 – 13 years | 30 – 60 micrograms, depending on age |
| 14 – 18 years | 75 micrograms |
| Men 19+ years | 120 micrograms |
| Women 19+ years | 90 micrograms |
| Pregnancy and breastfeeding | 75 – 90 micrograms, depending on age |
Foods rich in vitamin K: Dark leafy green vegetables (kale, chard, lettuce), vegetable oils
Notes:
- Bacteria in the gut can produce some vitamin K.
- Some medications may interact with vitamin K.
- Vitamin K transport across the placenta is low. Thus the American Academy of Pediatrics recommends newborns receive a vitamin K dose to prevent potential life-threatening vitamin K-deficiency bleeding in babies.
Choline
How choline works:
- Involved in the metabolism and transport of lipids
- Supports neurotransmitter production and nerve signaling
- Supports cell membrane structure
- Involved in cell-to-cell communication
- Supports numerous reactions in the body including those in homocysteine metabolism
How much choline do you need each day?
| Group | Amount |
| 0 – 12 months | 125 – 150 mg, depending on age |
| 1 – 13 years | 200 – 375 mg, depending on age |
| 14 – 18 years | 400 mg females, 550 mg males |
| 19+ years | 425mg females, 550 mg males |
| Pregnancy | 450 mg |
| Breastfeeding | 550 mg |
Good sources of choline:
- Eggs
- Dairy
- Poultry, meat, fish, liver
- Soybeans
- Cruciferous veggies (broccoli, cabbage, Brussels sprouts)
Note: Choline is a vitamin-like substance since the body is unable to make enough of it on its own.
Sources.
Content was curated using information from:
- The National Academy of Medicine’s Dietary Reference Intake manuals dated 2005 and newer
- The Dietary Guidelines for Americans 2015-2020
- The Office of Dietary Supplements Health Professional’s webpages (accessed Mar-April 2020)
- The Oregon State University’s Linus Pauling Institute’s Micronutrient Information Center (accessed Mar-Apr 2020)
- The USDA’s SR28 food database and FoodData Central database
- From peer-reviewed journal articles
- The American Academy of Pediatrics and American Pediatric Dental Association websites were referenced in Apr 2020 for their respective and current recommendations where noted
Content presented here, although created by US Registered Dietitians and PhD-level Nutritional Biologists, is for informational purposes only and is not intended to be medical advice. Consult your health care provider before using any supplements or making dietary changes.