Vitamin B1 (Thiamine)

Overview

Vitamin B1, or thiamine, is a water-soluble vitamin that plays a crucial role in carbohydrate metabolism and energy production. It also supports nerve, muscle, and heart function.

Key Functions in the Body

• Converts carbohydrates into energy (ATP production)
• Supports nerve impulse transmission
• Maintains healthy muscle function
• Essential for brain function and mood regulation

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Pork chops – 0.81 mg per 3 oz (68% DV)
• Sunflower seeds – 0.54 mg per 1 oz (45% DV)
• Brown rice – 0.19 mg per 1 cup cooked (16% DV)
• Black beans – 0.21 mg per 1 cup cooked (18% DV)
• Fortified breakfast cereals – up to 1.5 mg per serving (125% DV)

Health Benefits (Evidence-Based)

• Energy metabolism – Helps break down sugars for energy
• Nervous system support – Prevents nerve damage and maintains reflexes
• Cardiac health – Supports proper heart muscle contraction
• Cognitive function – Linked to better memory and mood regulation

Deficiency Symptoms & Causes

Symptoms:

• Fatigue, irritability
• Poor memory
• Muscle weakness
• Tingling in extremities

Severe Deficiency Conditions:

• Beriberi – Affects cardiovascular and nervous systems
• Wernicke-Korsakoff syndrome – Neurological disorder linked to alcoholism

Toxicity & Safe Upper Limits

• No established UL (excess usually excreted in urine)
• Very high supplemental doses may cause mild skin reactions

Scientific References

• National Institutes of Health (NIH): Thiamin Fact Sheet
• Food and Agriculture Organization (FAO): Vitamin B1 Data

Vitamin B2 (Riboflavin)

Overview

Vitamin B2, or riboflavin, is a water-soluble vitamin that plays a vital role in energy production, cellular function, and metabolism of fats, drugs, and steroids. It also helps maintain healthy skin and eyes.

Key Functions in the Body

• Helps convert carbohydrates, fats, and proteins into energy
• Supports antioxidant defense by regenerating glutathione
• Promotes healthy vision and skin
• Plays a role in red blood cell production

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Beef liver – 3.5 mg per 3 oz (269% DV)
• Almonds – 0.3 mg per 1 oz (23% DV)
• Eggs – 0.3 mg per large egg (23% DV)
• Milk – 0.4 mg per cup (31% DV)
• Mushrooms – 0.4 mg per cup cooked (31% DV)

Health Benefits (Evidence-Based)

• Energy metabolism – Assists in ATP production
• Antioxidant protection – Regenerates antioxidant enzymes
• Eye health – Reduces risk of cataracts
• Skin maintenance – Helps repair tissue damage

Deficiency Symptoms & Causes

Symptoms:

• Cracks at the corners of the mouth (cheilitis)
• Swollen tongue (glossitis)
• Skin rash
• Light sensitivity

Causes:

• Poor diet, alcoholism
• Certain medications (antidepressants, antimalarials)
• Malabsorption disorders

Toxicity & Safe Upper Limits

• No UL established — excess is excreted in urine
• High-dose supplements may cause bright yellow urine (harmless)

Scientific References

• NIH: Riboflavin Fact Sheet
• FAO: Vitamin B2 Data

Vitamin B3 (Niacin)

Overview

Vitamin B3, or niacin, is a water-soluble vitamin that helps convert food into energy and plays a role in DNA repair and stress responses. It exists as nicotinic acid and nicotinamide, both found in food and supplements.

Key Functions in the Body

• Converts carbohydrates, fats, and proteins into usable energy
• Supports skin health and digestive function
• Helps maintain nervous system function
• Plays a role in DNA synthesis and repair

Daily Recommended Intake (NIH Guidelines)

NE = Niacin Equivalents

Best Food Sources

• Chicken breast – 10.3 mg per 3 oz (64% DV)
• Tuna – 8.6 mg per 3 oz (54% DV)
• Turkey – 10 mg per 3 oz (62% DV)
• Brown rice – 2.6 mg per cup cooked (16% DV)
• Mushrooms – 3.6 mg per cup cooked (23% DV)

Health Benefits (Evidence-Based)

• Cholesterol control – Helps raise HDL and lower LDL
• Energy production – Supports enzymes for ATP generation
• Skin protection – Maintains healthy skin barrier
• Brain function – May reduce age-related cognitive decline

Deficiency Symptoms & Causes

Symptoms:

• Fatigue, headache
• Skin rash (pellagra)
• Digestive issues
• Mental confusion

Causes:

• Alcoholism
• Poor diet
• Hartnup disease (rare genetic condition)

Toxicity & Safe Upper Limits

UL: 35 mg/day (adults) from supplements
High doses may cause flushing, nausea, liver damage

Scientific References

• NIH: Niacin Fact Sheet

Vitamin B5 (Pantothenic Acid)

Overview

Vitamin B5 is a water-soluble vitamin essential for making coenzyme A (CoA), which is crucial in energy metabolism and synthesizing fatty acids, cholesterol, and steroid hormones.

Key Functions in the Body

• Produces CoA for energy metabolism
• Helps synthesize hormones and cholesterol
• Supports wound healing
• Aids red blood cell formation

Daily Recommended Intake (NIH Guidelines)

AI = Adequate Intake

Best Food Sources

• Beef liver – 8.3 mg per 3 oz (166% DV)
• Sunflower seeds – 2.4 mg per 1 oz (48% DV)
• Salmon – 1.9 mg per 3 oz (38% DV)
• Avocado – 2.0 mg per 1 fruit (40% DV)
• Mushrooms – 1.5 mg per cup cooked (30% DV)

Health Benefits (Evidence-Based)

• Energy support – Converts food into ATP
• Hormone production – Key in steroid and adrenal hormones
• Skin healing – Promotes tissue repair

Deficiency Symptoms & Causes

Rare, but may cause:

• Fatigue
• Irritability
• Numbness and muscle cramps

Toxicity & Safe Upper Limits

• No UL — excess excreted in urine
• Very high doses may cause diarrhea

Scientific References

• NIH: Pantothenic Acid Fact Sheet

Vitamin B6 (Pyridoxine)

Overview

Vitamin B6 is a water-soluble vitamin involved in more than 100 enzyme reactions, primarily in protein metabolism. It also supports brain development and immune function.

Key Functions in the Body

• Converts amino acids for protein metabolism
• Produces neurotransmitters (serotonin, dopamine)
• Supports hemoglobin production
• Regulates homocysteine levels

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Chickpeas – 1.1 mg per cup cooked (65% DV)
• Tuna – 0.9 mg per 3 oz (53% DV)
• Salmon – 0.6 mg per 3 oz (35% DV)
• Chicken breast – 0.5 mg per 3 oz (29% DV)
• Bananas – 0.4 mg per medium (24% DV)

Health Benefits (Evidence-Based)

• Brain health – Supports neurotransmitter synthesis
• Mood regulation – Linked to serotonin production
• Anemia prevention – Aids hemoglobin production

Deficiency Symptoms & Causes

Symptoms:

• Irritability, confusion
• Depression
• Anemia
• Nerve damage (in severe cases)

Causes:

• Alcoholism
• Kidney disease
• Certain medications (isoniazid, hydralazine)

Toxicity & Safe Upper Limits

UL: 100 mg/day (adults) from supplements
High doses may cause nerve damage

Scientific References

• NIH: Vitamin B6 Fact Sheet

Vitamin B7 (Biotin)

Overview

Vitamin B7, also known as biotin, is a water-soluble vitamin that plays an important role in the metabolism of carbohydrates, fats, and proteins. It’s often associated with healthy hair, skin, and nails.

Key Functions in the Body

• Supports the breakdown of macronutrients for energy
• Helps maintain healthy skin, hair, and nails
• Plays a role in gene regulation
• Supports nervous system function

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Egg yolk – 10 µg per large egg (33% DV)
• Salmon – 5 µg per 3 oz (17% DV)
• Sunflower seeds – 2.6 µg per 1 oz (9% DV)
• Sweet potato – 2.4 µg per 1 cup cooked (8% DV)
• Almonds – 1.5 µg per 1 oz (5% DV)

Health Benefits (Evidence-Based)

• Hair and nail health – May improve strength and thickness
• Skin health – Supports cell regeneration
• Metabolism support – Assists in energy production

Deficiency Symptoms & Causes

Symptoms:

• Thinning hair
• Skin rash (especially around eyes, nose, mouth)
• Fatigue
• Depression

Causes:

• Prolonged raw egg white consumption (contains avidin)
• Genetic disorders affecting biotin metabolism
• Long-term anticonvulsant use

Toxicity & Safe Upper Limits

• No UL established
• High doses generally considered safe, but may interfere with lab test results

Scientific References

• NIH: Biotin Fact Sheet

Vitamin B9 (Folate / Folic Acid)

Overview

Vitamin B9 is a water-soluble vitamin essential for DNA synthesis, cell division, and red blood cell formation. Folate is the natural form in food, while folic acid is the synthetic form used in supplements and fortified foods.

Key Functions in the Body

• Supports DNA and RNA synthesis
• Helps form healthy red blood cells
• Essential for fetal neural tube development
• Plays a role in amino acid metabolism

Daily Recommended Intake (NIH Guidelines)

DFE = Dietary Folate Equivalents

Best Food Sources

• Lentils – 358 µg per cup cooked (90% DV)
• Spinach – 263 µg per cup cooked (66% DV)
• Black-eyed peas – 358 µg per cup cooked (90% DV)
• Fortified cereals – 100–400 µg per serving (25–100% DV)
• Asparagus – 134 µg per cup cooked (34% DV)

Health Benefits (Evidence-Based)

• Prevents neural tube defects in pregnancy
• Supports blood health – prevents megaloblastic anemia
• May reduce stroke risk through homocysteine reduction

Deficiency Symptoms & Causes

Symptoms:

• Fatigue, weakness
• Irritability
• Shortness of breath
• Anemia

Causes:

• Poor diet, alcoholism
• Malabsorption disorders
• Certain medications (methotrexate, phenytoin)

Toxicity & Safe Upper Limits

UL: 1,000 µg/day from fortified foods/supplements
Excess may mask vitamin B12 deficiency

Scientific References

• NIH: Folate Fact Sheet

Vitamin B12 (Cobalamin)

Overview

Vitamin B12 is a water-soluble vitamin essential for nerve tissue health, brain function, and red blood cell production. It is found naturally only in animal products.

Key Functions in the Body

• Supports red blood cell formation
• Maintains nerve cell function
• Helps produce DNA
• Works with folate in cell division

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Clams – 84 µg per 3 oz (3,500% DV)
• Beef liver – 70 µg per 3 oz (2,900% DV)
• Salmon – 4.8 µg per 3 oz (200% DV)
• Fortified plant milk – 1–3 µg per cup (40–125% DV)
• Eggs – 0.6 µg per large egg (25% DV)

Health Benefits (Evidence-Based)

• Prevents megaloblastic anemia
• Supports brain health – may reduce dementia risk
• Boosts energy levels in deficiency cases

Deficiency Symptoms & Causes

Symptoms:

• Fatigue, weakness
• Numbness or tingling in hands/feet
• Memory problems
• Mood changes

Causes:

• Vegan/vegetarian diets without supplementation
• Pernicious anemia
• Gastrointestinal surgery or disorders

Toxicity & Safe Upper Limits

• No UL established
• High doses generally safe but unnecessary unless treating deficiency

Scientific References

• NIH: Vitamin B12 Fact Sheet

Vitamin C (Ascorbic Acid)

Overview

Vitamin C is a water-soluble vitamin and antioxidant that supports immune health, collagen production, and wound healing. It also enhances iron absorption from plant foods.

Key Functions in the Body

• Acts as an antioxidant
• Helps produce collagen for skin, cartilage, and bones
• Supports immune system
• Enhances non-heme iron absorption

Daily Recommended Intake (NIH Guidelines)

Best Food Sources

• Red bell pepper – 95 mg per ½ cup raw (106% DV)
• Orange – 70 mg per medium (78% DV)
• Kiwi – 64 mg per fruit (71% DV)
• Strawberry – 59 mg per cup (66% DV)
• Broccoli – 51 mg per cup cooked (57% DV)

Health Benefits (Evidence-Based)

• Boosts immune defense
• Supports skin health via collagen production
• Helps prevent scurvy
• May shorten cold duration (slightly)

Deficiency Symptoms & Causes

Symptoms:

• Fatigue
• Bleeding gums
• Slow wound healing
• Easy bruising

Causes:

• Poor diet lacking fruits/vegetables
• Smoking (increases vitamin C needs)

Toxicity & Safe Upper Limits

UL: 2,000 mg/day
Excess may cause diarrhea and stomach cramps

Scientific References

• NIH: Vitamin C Fact Sheet