What is the recommended dosage for Vitamin A?

General: 700-900 mcg RAE/day (RDA for adults); Gut Barrier Support: 900 mcg RAE/day from mixed sources; Deficiency Correction: 200,000 IU single dose (WHO protocol for severe deficiency, medical supervision)

What are the side effects of Vitamin A?

Potential side effects include: Hepatotoxicity at chronic high doses of preformed vitamin A, Birth defects (teratogenic at high doses during pregnancy — avoid >3,000 mcg RAE/day), Nausea, headache, and dizziness, Bone density reduction with long-term excess.

What is vitamin A and how does it work for gut health?

Vitamin A is a fat-soluble vitamin essential for maintaining the integrity of mucosal surfaces throughout the body, including the intestinal lining. It supports the differentiation and function of epithelial cells that form the gut barrier, and plays a critical role in mucosal immune responses, including the production of secretory IgA. Vitamin A deficiency is associated with increased intestinal permeability and susceptibility to gastrointestinal infections.

What is the recommended dosage of vitamin A for gut health?

The recommended daily allowance is 900 mcg RAE (3,000 IU) for adult men and 700 mcg RAE (2,333 IU) for adult women. For gut health support, supplemental doses used in studies range from 5,000-10,000 IU per day. Beta-carotene (provitamin A) is a safer alternative at 15-30 mg per day, as the body converts it to vitamin A as needed, reducing toxicity risk.

Are there side effects or interactions with vitamin A?

Preformed vitamin A (retinol) can be toxic at high doses, causing nausea, headache, liver damage, and birth defects in pregnancy. The tolerable upper intake level is 3,000 mcg RAE (10,000 IU) per day for adults. Vitamin A may interact with retinoid medications (isotretinoin, tretinoin), warfarin, and hepatotoxic drugs. Pregnant women should not exceed the RDA without medical supervision.

Vitamin A

vitamin

Also known as: Retinol, Retinyl Palmitate, Beta-Carotene (provitamin A), Retinoic Acid

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About

Vitamin A plays a critical role in maintaining intestinal epithelial cell differentiation and turnover through retinoic acid signaling. It supports goblet cell mucus production, which forms a key component of the intestinal barrier, and is required for secretory IgA transport across mucosal surfaces. Research suggests vitamin A supplementation may help support intestinal barrier integrity and immune defense, particularly in deficient populations.

How It Works

Maintains intestinal epithelial cell differentiation and turnover via retinoic acid signaling through RAR/RXR nuclear receptors; supports goblet cell mucus production forming the protective mucus layer; required for secretory IgA transport across mucosal surfaces; modulates Th17/Treg balance in gut-associated lymphoid tissue (GALT).

Evidence For Conditions

Condition	Grade	Studies	Participants
Increased Intestinal Permeability (Leaky Gut)	C	3	250	View →
Acute Diarrhea	D	3	500	View →

Side Effects

Hepatotoxicity at chronic high doses of preformed vitamin A
Birth defects (teratogenic at high doses during pregnancy — avoid >3,000 mcg RAE/day)
Nausea, headache, and dizziness
Bone density reduction with long-term excess

Drug & Supplement Interactions

Retinoid medications (isotretinoin, tretinoin — additive toxicity risk)
Orlistat (reduces absorption of fat-soluble vitamins)
Alcohol (increases hepatotoxicity risk of vitamin A)
Tetracycline antibiotics (increased risk of intracranial pressure)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Vitamin D

Quick Facts

Dosage: General: 700-900 mcg RAE/day (RDA for adults); Gut_Barrier_Support: 900 mcg RAE/day from mixed sources; Deficiency_Correction: 200,000 IU single dose (WHO protocol for severe deficiency, medical supervision)
Forms: capsule softgel liquid cod liver oil
Natural Sources: Liver (highest preformed source), Sweet potatoes, Carrots, Spinach, Kale, Eggs, Cod liver oil
Upper Limit: 3,000 mcg RAE/day (preformed vitamin A; beta-carotene has no established UL)
Best Time: With meals containing fat for better absorption

Evidence Summary

Increased Intestinal Permeability (Leaky Gut) C

Acute Diarrhea D

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.