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Vitamin A

Vitamin A refers to a group of compounds that serve important roles in modulating skin health, vision, gene transcription, and immune system functioning. Deficiencies, which are common in developing countries, can lead to impaired vision, dry skin and poor immunity.

Our evidence-based analysis on vitamin a features 18 unique references to scientific papers.

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Summary of Vitamin A

Primary information, health benefits, side effects, usage, and other important details

Vitamin A is not a single compound but a group of chemical compounds that are structurally similar. These compounds include retinol, retinaldehyde, retinoic acid, and provitamin A caretenoids which include beta-carotene, alpha-carotene, gamma-carotene and cryptoxanthin. Retinol and beta-carotene are some of the most common forms of vitamin A found in food and supplements, with the former being found in animals and the latter in plants.

Vitamin A is involved in the modulation of skin health, vision, the immune system, and gene transcription. Different forms of vitamin A will serve different functions. For example, it is retinoic acid that is involved in gene transcription and the maintenance of skin health; it is retinaldehyde that binds certain proteins to the cones and rods of the eye, allowing the eye to function in low-light environments.

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How to Take

Recommended dosage, active amounts, other details

For topical application, the form of all-trans retinoic acid (Tretinoin) should be used in a facial cream/lotion containing it in the range of 0.01-0.10%, with the lowest concentration having low side-effects but less efficacy and 0.025-0.05% being the sweet spot. Topical application is once nightly.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects Vitamin A has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-b Notable Very High See all 3 studies
The appearance of fine (small) wrinkles appears to be reliably reduced with topical application of a nightly vitamin A cream, with efficacy in all ages assuming fine wrinkles are present.
grade-b Minor Very High See all 3 studies
Skin dryness is a side-effect of topical application in some persons, increasing in frequency with higher doses; it is mild in severity and, while it may be associated with flaking, rarely causes dropouts.
grade-b - - See all 3 studies
grade-b - - See all 3 studies
grade-c - - See study
grade-c - - See study
grade-c - - See 2 studies

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Things to Note

Also Known As

retinol, retinal, retinoic acid, tretinoin, beta-carotene

Caution Notice

Supplements or foods high in retinol should be consumed carefully due to its fat-soluble nature. It is more difficult to clear fat-soluble compounds from the body than water-soluble compounds. A medical practitioner should be consulted before ingesting high amounts of retinol.

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Click here to see all 18 references.