Vitamin A

Overview

Vitamin A is used by the body to make every steroid hormone from cholesterol, including pregnenolone, progesterone, DHEA, and the testosterone and cortisol pathways. It travels through the blood on the same carrier protein as thyroid hormone, and the two work so closely together that without enough vitamin A you cannot make use of cholesterol, and without enough thyroid you cannot make use of vitamin A. The skin, eyes, mucus membranes, and immune system all depend on it. The reputation it has for being uniquely toxic is largely a fabrication promoted by drug companies trying to sell synthetic patentable retinoids. The healthier and more metabolically active a person is, the more vitamin A they need.

Key Points

• Vitamin A is required for the steroid synthesis enzymes that build progesterone and DHEA from pregnenolone. The two key enzymes, 3-beta-hydroxysteroid dehydrogenase and 17-alpha-hydroxylase, will not function properly without sufficient vitamin A. If you are deficient, none of your downstream steroids will be optimal: progesterone, DHEA, testosterone, and DHT will all run low while cholesterol accumulates upstream. This is why high cholesterol on a blood test can point to a vitamin A deficiency rather than a dietary cholesterol problem.

• Vitamin A and thyroid hormone travel on a single protein called transthyretin. This shared transport explains why their effects are so tightly coupled. When a hypothyroid person can't use vitamin A properly, carotene accumulates in the steroid-forming tissues. In the 1930s, one way of confirming death from hypothyroidism was the red colour of tissue from accumulated carotene. Yellow calluses on the palms and soles were a classic clinical sign of low thyroid for the same reason.

• Carotene is not vitamin A and behaves like a polyunsaturated fat. Carotene is highly unsaturated and blocks both the cellular sites that would use vitamin A and thyroid in the same way that vegetable oils do. Some studies that confused researchers showed cancer increased with carotene supplementation, even though real vitamin A is protective. Vitamin B12 is required to break carotene into two molecules of vitamin A, so a B12 deficiency causes carotene to pile up and vitamin A to drop.

• Healthy, metabolically active people need much more vitamin A than the FDA acknowledges. The dentist and nutrition researcher Emanuel Cheraskin surveyed people at his conventions and published a chart showing a straight-line inverse relationship between symptoms and vitamin A intake, all the way up to 100,000 IU per day. In Ray's twenties he needed around 50,000 IU per day. When thyroid function is high, cholesterol gets converted to progesterone faster, which uses vitamin A faster.

• Sunlight, X-rays, and intense light exposure consume vitamin A. The retina uses a lot of vitamin A to make visual pigment, and bright light entering the eye also activates the hormonal system, which consumes more vitamin A. Ray noticed acne flared in proportion to his sun exposure (or even artificial light shining on his closed eyes overnight). Increasing vitamin A in proportion to light exposure prevented the acne. Vitamin A is also destroyed by ultraviolet light and X-rays, so dental X-rays and sunburn raise the requirement.

• Vitamin A can clear precancerous lesions like leukoplakia. Ray cured leukoplakia in his cheek overnight with a big dose of vitamin A, and he repeated the result several times when dentists diagnosed him with the condition over the years. Cervical leukoplakia ("carcinoma in situ" on a Pap smear) is biologically almost identical to the mouth version, and three dozen women he advised to apply vitamin A topically returned to their doctors with normal Pap smears.

• The "vitamin A is toxic" narrative is largely manufactured. The classic 80-year-old story of Arctic explorers getting sick from polar bear liver almost certainly involved algae toxins from contaminated fish stored briefly in the bear's liver, not vitamin A itself. Around the time drug companies were launching synthetic retinoids like Retin-A, sudden news releases appeared from medical schools claiming people had gone blind from vitamin A. When Ray phoned the relevant University of Oregon department to verify one of the stories, no one could confirm it. A naturopath's book claiming chronic vitamin A toxicity is the cause of most autoimmune diseases contained no facts on examination.

• Deficiency presents as soft muscles, poor sleep, low androgens, and dandruff. Without adequate vitamin A, men become deficient in testosterone and progesterone - their muscles feel soft, sleep is poor, and metabolism doesn't work properly. Ray Peat identified dandruff as a common sign of deficiency. Most people are deficient because they no longer eat the organ meats that traditionally supplied vitamin A.

• Eggs, liver, milk, cheese, and halibut liver oil are the practical sources. Liver of any kind, fish or chicken or beef, is the densest source (although fish liver is usually high in PUFA). Halibut liver oil delivers a lot of vitamin A and some D with very little PUFA, so it is one of the few fish-derived oils that is reasonable to use. Eggs and dairy round out a normal diet.

Notable Quotes

"The brain is probably the most powerful steroid-forming organ when it's working right, and vitamin A is essential for making those (steroids)."

[Ray Peat — KMUD: Memory, Cognition and Nutrition]

"Someone sent me these books by a recent author claiming that there is vitamin A toxicity rampant. I looked through it and couldn't find any facts at all."

[Ray Peat — KMUD: Postpartum Depression]

"I took a big dose of vitamin A and it immediately, overnight, cleared up the leukoplakia."

[Ray Peat — Safe Supplements with Ray Peat, Generative Energy #31]

"And then since I knew that leukoplakia of the cervix is biologically almost indistinguishable from leukoplakia inside the cheek, I told women who had abnormal pap smears and biopsies showing so-called carcinoma in situ and they tried applying vitamin A topically. And I kept track of three dozen women who had that experience... They went back two or three months later with no evidence of abnormality"

[Ray Peat — KMUD: Cancer Treatment]

"The main issue with vitamin A toxicity that I've seen is due to the fact that the vitamin A molecule is very structurally similar in terms of saturation to the polyunsaturated paths. So it very easily peroxidizes."

[Georgi Dinkov — Georgi Dinkov and I Discuss Weight Problems]

"There are human studies using up to 500,000, even a million units a day for treating things like leukemia, because vitamin A is one of the treatments for acute lymphoblastic leukemia, several of the leukemias, and basically people tolerate it... up to a million units a day taken with vitamin E in human studies did not show any noticeable toxicity."

[Georgi Dinkov — Georgi Dinkov and I Discuss Weight Problems]

"Vitamin A and progesterone are so close in terms of activity in the tissues that in the early 1930s up until the mid 1940s, vitamin A was used as a progesterone surrogate."

[Georgi Dinkov — Nitric Oxide and Methylene Blue]

Important Things To Consider

Several hundred thousand units a day will eventually suppress thyroid. This is the genuine upper-bound concern. In a person with borderline thyroid function, even a single 100,000 IU dose can produce a noticeable dip in thyroid activity, because vitamin A and thyroid travel on the same transport protein and one can displace the other. This effect shows up only at extreme doses and is reversible.

Vitamin A "toxicity" is mostly vitamin E deficiency. Animal studies that found excess vitamin A caused brain malformation in developing chicks also found that adding vitamin E stopped the effect. The toxic species is the auto-oxidized product of vitamin A, not vitamin A itself. Adequate vitamin E prevents the toxic oxidation.

Carotene supplements and high-carotene foods can cause functional vitamin A deficiency. Cooked carrots, cooked pumpkin, and concentrated carrot juice deliver large amounts of carotene. Without enough thyroid and B12 to convert it, carotene piles up, blocks the vitamin A receptors, and creates the same anti-thyroid problems as PUFA. Orange tints on the palms and soles are a warning sign.

Supplement quality has been unreliable since manufacturing moved to China. Ray took 50,000 to 100,000 IU per day with no issue for years when vitamin A was made in the US, but after production shifted to China around the 2010s he developed extreme sensitivity, eventually getting migraines from a touch of it on his lips. The vitamin A molecule is the same; the problem is contaminants and excipients. Vitamin A supplements should be used very carefully.

Without B12, carotene cannot be converted into vitamin A. A vegetarian Ray knew had extremely high blood carotene and undetectable vitamin A; within a week of taking B12 his vitamin A normalized, his carotene levels dropped and his symptoms cleared. Anyone with high carotene and low retinol should look at B12 first.

Synthetic retinoic acid derivatives are not the same as natural vitamin A. Drugs like Accutane (isotretinoin) and tretinoin accumulate because the liver cannot fully metabolise them, and they cause severe birth defects. Anyone reading about "vitamin A toxicity" needs to check whether the source is talking about natural retinol or one of these synthetic derivatives, because the safety profiles are completely different.

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