Essential Vitamins
Vitamins are organic compounds that your body needs in small amounts to function properly. They support everything from vision and immune health to energy production and blood clotting.
Vitamin A
Vitamin A is a fat-soluble vitamin crucial for vision (especially night vision), immune function, reproduction, and cellular communication. It also supports the health of skin, teeth, and mucous membranes.
Risks of Not Having Enough (Deficiency)
- Night blindness and vision problems
- Dry eyes (xerophthalmia)
- Increased susceptibility to infections
- Dry, rough skin
- Impaired growth in children
Risks of Having Too Much (Toxicity)
- Nausea, headache, dizziness
- Liver damage (chronic excess)
- Birth defects (during pregnancy)
- Bone thinning and joint pain
- Skin changes (peeling, dryness)
Food Sources
| Food | Serving Size | Vitamin A (mcg RAE) |
| Sweet potato (baked) | 1 medium (114 g) | 1,403 |
| Beef liver | 3 oz (85 g) | 6,582 |
| Carrots (raw) | 1/2 cup (61 g) | 459 |
| Spinach (cooked) | 1/2 cup (90 g) | 573 |
| Cantaloupe | 1/2 cup (78 g) | 135 |
| Red bell pepper | 1/2 cup (75 g) | 117 |
| Mango | 1 cup (165 g) | 89 |
*USRDA for adults: 900 mcg RAE (men), 700 mcg RAE (women)
Summary of Genetic Impact
Variants in the BCMO1 gene can significantly reduce the conversion of beta-carotene (from plant sources) into active vitamin A. People with certain BCMO1 variants may need preformed vitamin A from animal sources or supplements to meet their needs.
Vitamin B2 (Riboflavin)
Riboflavin is a water-soluble B vitamin essential for energy production, cellular function, and the metabolism of fats, drugs, and steroids. It also acts as an antioxidant and is important for maintaining healthy skin and eyes.
Risks of Not Having Enough (Deficiency)
- Cracked and sore lips (cheilosis)
- Sore throat and mouth
- Inflammation of the tongue (glossitis)
- Skin disorders
- Anemia
- Eye fatigue and sensitivity to light
Risks of Having Too Much (Toxicity)
- Toxicity is very rare (excess is excreted in urine)
- Bright yellow urine (harmless indicator of excess)
Food Sources
| Food | Serving Size | Vitamin B2 (mg) |
| Beef liver | 3 oz (85 g) | 2.9 |
| Fortified breakfast cereal | 1 serving | 1.3 |
| Yogurt (plain, fat-free) | 1 cup (245 g) | 0.6 |
| Milk | 1 cup (244 g) | 0.4 |
| Almonds | 1 oz (28 g) | 0.3 |
| Eggs | 1 large (50 g) | 0.2 |
| Spinach (cooked) | 1/2 cup (90 g) | 0.2 |
*USRDA for adults: 1.3 mg (men), 1.1 mg (women)
Summary of Genetic Impact
Variants in the MTHFR gene (especially C677T) can increase riboflavin requirements, as riboflavin is a cofactor for the MTHFR enzyme involved in folate metabolism. People with these variants may benefit from higher B2 intake.
Vitamin B6 (Pyridoxine)
Vitamin B6 is involved in over 100 enzyme reactions in the body, primarily related to protein metabolism. It also plays roles in cognitive development, immune function, and the production of neurotransmitters like serotonin and dopamine.
Risks of Not Having Enough (Deficiency)
- Anemia
- Skin rashes (dermatitis)
- Cracked corners of the mouth
- Depression and confusion
- Weakened immune function
- Swollen tongue
Risks of Having Too Much (Toxicity)
- Peripheral neuropathy (numbness, tingling in extremities)
- Loss of coordination
- Painful skin lesions
- Sensitivity to sunlight
- Nausea and heartburn
Food Sources
| Food | Serving Size | Vitamin B6 (mg) |
| Chickpeas (canned) | 1 cup (164 g) | 1.1 |
| Beef liver | 3 oz (85 g) | 0.9 |
| Yellowfin tuna | 3 oz (85 g) | 0.9 |
| Chicken breast | 3 oz (85 g) | 0.5 |
| Banana | 1 medium (118 g) | 0.4 |
| Potato (baked) | 1 medium (173 g) | 0.4 |
| Fortified breakfast cereal | 1 serving | 0.5 |
*USRDA for adults (19-50): 1.3 mg per day
Summary of Genetic Impact
Genetic variants in the ALPL gene (which encodes alkaline phosphatase, involved in B6 metabolism) and NBPF3 can affect circulating B6 levels. Some individuals may require higher dietary B6 intake based on their genetic profile.
Vitamin B9 (Folate)
Folate is essential for DNA synthesis, cell division, and amino acid metabolism. It is especially critical during periods of rapid growth, such as pregnancy and fetal development, where it helps prevent neural tube defects.
Risks of Not Having Enough (Deficiency)
- Megaloblastic anemia (large, abnormal red blood cells)
- Neural tube defects in developing fetuses
- Fatigue and weakness
- Elevated homocysteine (cardiovascular risk)
- Mouth sores and tongue swelling
- Mood changes (irritability, difficulty concentrating)
Risks of Having Too Much (Toxicity)
- Can mask vitamin B12 deficiency symptoms
- May promote growth of existing cancerous cells (high supplemental folic acid)
- Possible interference with certain medications
Food Sources
| Food | Serving Size | Folate (mcg DFE) |
| Beef liver | 3 oz (85 g) | 215 |
| Spinach (cooked) | 1/2 cup (90 g) | 131 |
| Black-eyed peas (cooked) | 1/2 cup (86 g) | 105 |
| Asparagus | 4 spears (60 g) | 89 |
| Brussels sprouts (cooked) | 1/2 cup (78 g) | 78 |
| Fortified breakfast cereal | 1 serving | 100-400 |
| Avocado | 1/2 fruit (68 g) | 59 |
*USRDA for adults: 400 mcg DFE per day (600 mcg during pregnancy)
Summary of Genetic Impact
The MTHFR C677T and A1298C variants are well-known genetic factors that reduce the enzyme's ability to convert folate into its active form (5-MTHF). Individuals with these variants may benefit from methylfolate supplements rather than standard folic acid.
Vitamin B12 (Cobalamin)
Vitamin B12 is essential for red blood cell formation, neurological function, and DNA synthesis. It is naturally found only in animal-derived foods, making supplementation important for those following plant-based diets.
Risks of Not Having Enough (Deficiency)
- Megaloblastic anemia
- Peripheral neuropathy (tingling, numbness)
- Fatigue and weakness
- Cognitive difficulties (memory loss, confusion)
- Balance problems
- Depression
- Glossitis (sore, swollen tongue)
Risks of Having Too Much (Toxicity)
- Toxicity from food sources is extremely rare
- No established upper limit (excess is excreted)
- Very high supplemental doses may rarely cause acne or rosacea
Food Sources
| Food | Serving Size | Vitamin B12 (mcg) |
| Clams | 3 oz (85 g) | 84.1 |
| Beef liver | 3 oz (85 g) | 70.7 |
| Nutritional yeast (fortified) | 1 tbsp (5 g) | 2.4 |
| Trout | 3 oz (85 g) | 3.5 |
| Salmon | 3 oz (85 g) | 4.8 |
| Milk | 1 cup (244 g) | 1.2 |
| Eggs | 1 large (50 g) | 0.6 |
*USRDA for adults: 2.4 mcg per day
Summary of Genetic Impact
Variants in FUT2 (which affects B12 absorption in the gut) and TCN2 (which affects B12 transport in the blood) can influence B12 status. People with certain variants may have lower B12 levels despite adequate dietary intake and may need higher supplementation.
Vitamin C (Ascorbic Acid)
Vitamin C is a powerful antioxidant essential for the growth, development, and repair of all body tissues. It is involved in collagen formation, iron absorption, immune function, wound healing, and maintenance of cartilage, bones, and teeth.
Risks of Not Having Enough (Deficiency)
- Scurvy (fatigue, swollen gums, joint pain)
- Slow wound healing
- Dry, splitting hair and rough skin
- Weakened immune system
- Easy bruising
- Iron-deficiency anemia (reduced iron absorption)
Risks of Having Too Much (Toxicity)
- Diarrhea, nausea, abdominal cramps
- Kidney stones (in susceptible individuals)
- Excess iron absorption (problematic for those with hemochromatosis)
Food Sources
| Food | Serving Size | Vitamin C (mg) |
| Red bell pepper | 1/2 cup (75 g) | 95 |
| Orange | 1 medium (131 g) | 70 |
| Kiwi | 1 medium (75 g) | 64 |
| Broccoli (cooked) | 1/2 cup (78 g) | 51 |
| Strawberries | 1/2 cup (76 g) | 49 |
| Brussels sprouts (cooked) | 1/2 cup (78 g) | 48 |
| Grapefruit | 1/2 fruit (128 g) | 39 |
*USRDA for adults: 90 mg (men), 75 mg (women)
Summary of Genetic Impact
Variants in the SLC23A1 gene (a vitamin C transporter) can affect how efficiently your body absorbs and maintains vitamin C levels. Some individuals with certain genetic profiles may need higher dietary intake to achieve optimal blood levels of vitamin C.
Vitamin D
Vitamin D is a fat-soluble vitamin unique in that your body can produce it when skin is exposed to sunlight. It is essential for calcium absorption, bone health, immune function, and mood regulation.
Risks of Not Having Enough (Deficiency)
- Rickets in children (soft, weak bones)
- Osteomalacia in adults (bone pain, muscle weakness)
- Increased risk of osteoporosis
- Weakened immune function
- Increased risk of depression
- Fatigue
Risks of Having Too Much (Toxicity)
- Hypercalcemia (nausea, vomiting, weakness)
- Kidney damage and kidney stones
- Calcium deposits in soft tissues
- Confusion and disorientation
- Heart rhythm abnormalities
Food Sources
| Food | Serving Size | Vitamin D (mcg) |
| Cod liver oil | 1 tbsp (14 g) | 34.0 |
| Trout | 3 oz (85 g) | 16.2 |
| Salmon (sockeye) | 3 oz (85 g) | 14.2 |
| Fortified milk | 1 cup (244 g) | 2.9 |
| Sardines (canned) | 2 sardines (24 g) | 1.2 |
| Egg yolk | 1 large | 1.1 |
| Fortified orange juice | 1 cup (248 g) | 2.5 |
*USRDA for adults (19-70): 15 mcg (600 IU) per day
Summary of Genetic Impact
Variants in VDR (vitamin D receptor), GC (vitamin D binding protein), CYP2R1, and CYP27B1 genes can all affect vitamin D metabolism, transport, and activation. These genetic differences can significantly influence individual vitamin D requirements and optimal supplementation levels.
Vitamin E
Vitamin E is a fat-soluble antioxidant that protects cells from oxidative damage. It also plays roles in immune function, cell signaling, and widening blood vessels to prevent blood clotting.
Risks of Not Having Enough (Deficiency)
- Nerve and muscle damage
- Loss of body movement control (ataxia)
- Weakened immune function
- Vision problems (retinopathy)
- Muscle weakness
Risks of Having Too Much (Toxicity)
- Increased bleeding risk (interferes with blood clotting)
- Nausea, diarrhea, fatigue
- Possible increased risk of hemorrhagic stroke
- Interaction with blood-thinning medications
Food Sources
| Food | Serving Size | Vitamin E (mg) |
| Wheat germ oil | 1 tbsp (14 g) | 20.3 |
| Sunflower seeds | 1 oz (28 g) | 7.4 |
| Almonds | 1 oz (28 g) | 7.3 |
| Hazelnuts | 1 oz (28 g) | 4.3 |
| Peanut butter | 2 tbsp (32 g) | 2.9 |
| Spinach (cooked) | 1/2 cup (90 g) | 1.9 |
| Avocado | 1/2 fruit (68 g) | 2.1 |
*USRDA for adults: 15 mg per day
Summary of Genetic Impact
Variants in genes involved in lipid metabolism (such as APOA5, SCARB1, and CYP4F2) can influence vitamin E absorption, transport, and metabolism. These genetic factors may affect optimal vitamin E intake requirements for different individuals.
Vitamin K
Vitamin K is a fat-soluble vitamin essential for blood clotting (coagulation) and bone metabolism. It exists in two main forms: K1 (phylloquinone, from plants) and K2 (menaquinone, from animal foods and fermented products).
Risks of Not Having Enough (Deficiency)
- Excessive bleeding and easy bruising
- Weakened bones and increased fracture risk
- Calcification of blood vessels
- Hemorrhagic disease in newborns
Risks of Having Too Much (Toxicity)
- No known toxicity from food sources of K1 or K2
- Synthetic vitamin K3 (menadione) can cause toxicity
- Can interfere with blood-thinning medications (warfarin)
Food Sources
| Food | Serving Size | Vitamin K (mcg) |
| Kale (cooked) | 1 cup (130 g) | 1,062 |
| Spinach (raw) | 1 cup (30 g) | 145 |
| Broccoli (cooked) | 1/2 cup (78 g) | 110 |
| Brussels sprouts (cooked) | 1/2 cup (78 g) | 109 |
| Natto (fermented soybeans) | 1 oz (28 g) | 313 |
| Green peas | 1/2 cup (80 g) | 21 |
| Chicken breast | 3 oz (85 g) | 13 |
*Adequate Intake (AI) for adults: 120 mcg (men), 90 mcg (women)
Summary of Genetic Impact
Variants in VKORC1 (vitamin K epoxide reductase) significantly affect vitamin K recycling and are the primary genetic factor influencing warfarin dose requirements. Variants in CYP4F2 can also affect vitamin K metabolism and individual requirements.
References
References
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