Biotin

What the science says (1990–2026): Biotin

These citations support correction of deficiency, specified forms, and elemental amounts — the same logic used in MD's Choice formulas. They are not claims that a supplement treats disease.

Zempleni 2009; FDA 2017–2022 lab-interference alerts; 2024 reviews. Biotin is essential. High-dose biotin can falsely skew thyroid and troponin lab tests — a safety fact, not a reason to avoid food-level biotin.

These products are not intended to diagnose, treat, cure, or prevent disease. Historic monograph text below is kept for the original library.

Biotin

I. Functions

Biotin is covalently bound to enzymes in cells

Pyruvate carboxylase
1. Catalyzes carboxylation of pyruvate to form oxaloacetate
2. Requires acetyl CoA, ATP, and Mg⁺²
3. If there is a surplus of ATP in the cell, the oxaloacetate is used for gluconeogenesis
4. If there is a deficiency of ATP, the oxaloacetate will enter the Krebs cycle on condensation with acetyl CoA
Acetyl CoA carboxylase
1. Converts acetyl CoA to malonyl CoA
2. This commits acetate units to fatty acid synthesis
3. ATP and Mg⁺² are required
Propionyl CoA carboxylase
1. Catabolism of isoleucine, threonine, and methionine, which each generate propionyl CoA
2. Catabolizes odd-number chain fatty acids which also generate propionyl CoA
3. Catalyzes carboxylation of propionyl CoA to methylmalonyl CoA. The reaction requires ATP and Mg⁺²
4. Methylmalonyl CoA is converted to succinyl CoA by racemase in a vitamin B12-dependent reaction
B-methylcrotonyl CoA carboxylase
1. B-methylcrotonyl CoA formed during leucine catabolism is carboxylated to form B-methylglutaconyl CoA
2. this is further catabolized to generated acetoacetate and acetyl CoA

II. Sources

Biotin is widely distributed in plants and animals

Yeast, liver, milk, cereals, tomatoes, and molasses are rich sources

III. Metabolism

Absorption

Protein bound biotin is catabolized by proteolytic enzymes to yield biocytin
Biocytin is degraded by biotinidase to yield free biotin, lycine and other amino acids
Biotin is absorbed primarilyy from the upper small intestine and in decreasing amounts further down
Absorption is carrier mediated and thought to require Na. - Absorption may or may not require energy
Both free and protein-bound biotin are found in plasma
Uptake of biotin by tissues is related to need
Distribution within cells corresponds to localization of carboxylases requiring biotin as the coenzyme

Excretion

Biotin enzymes are catabolized by proteases to yield biocytin
Biocytin is degraded by biotinidase to yield free biotin
1. Some is reused
2. Some is excreted
Biotin and biocytin are excreted in urine
Unabsorbed biotin is excreted in feces

IV. Requirements

Human - RDA has not been established

Uncertain contribution of intestinal synthesis
Incomplete knowledge about bioavailability of food biotin
Safe and adequate intake is estimated at 100-200 mg/day.

Poultry - 100-200 mg/kg BW

Rat - 300 mg/kg BW

V. Deficiency

Human

Factors increasing likelihood of deficiency
1. Excess consumption of raw eggs
2. Inflammatory bowel disease
3. Achlorhydria (lack of HCI in gastric juice)
4. Anticonvulsant drug therapy
5. Alcoholism
Deficiency symptoms
1. Depression, hallucinations
2. Muscle pain, paresthesia (burning, prickling sensation on the skin)
3. Anorexia, nausea
4. Alopecia, scaly dermatitis

Chicks

Dermatitis in feet and beak, perosis
Reduced hatchability

Pigs

Alopecia, seborrheic skin lesions, cracks in feet
Spasticity of hind legs

VI. Toxicity

Toxicity of biotin has not been reported

Oral doses over 60 pg/day for over 6 months have not produced side effects

Vitamin A	Vitamin B1 (Thiamin)	Vitamin B2 (Riboflavin)	Vitamin B3 (Niacin)
Vitamin B5 (Pantothenic Acid)	Vitamin B6	Vitamin B12	Vitamin C
Vitamin D	Vitamin E	Vitamin K	Biotin
Folic Acid

Calcium	Magnesium	Phosphorus	Sodium, Potassium, Chloride
Sulfur (Sulfer)

Boron	Chromium	Cobalt	Copper
Fluorine	Iodine	Iron	Manganese
Molybdenum	Nickel (Nickle)	Selenium	Silicon
Tin	Vanadium	Zinc	Ultra Trace

Aluminum	Arsenic	Cadmium	Lead
Mercury

What the science says (1990–2026): Biotin

Vitamins, Major Elements, Trace Elements, Toxic Elements

Vitamins

Major Elements

Trace Elements

Toxic Elements

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