This archived forum used to be called 'Peatarian' (in reference to Ray Peat).

Study: The effect of vitamin A supplementation on thyroid function

Summary: Vitamin A (25000 IU/d) => lower TSH, T4, higher T3.

See RPF thread here:

I wonder how large the observed effects were? Has anyone access to the full study?

asked Mar 9, 2015 by nograde

2 Answers

I think Peat has made clear that Vitamin A is biphasic (too little is anti-thyroid, as is too much) and the amount you need depends on how many calories you are metabolizing in a day. No study is likely to be designed with this in mind.

For example, Peat recalls that when he was metabolizing 6,000 calories in a day he needed I think 50,000 IU of Vitamin A, but when he became more sedentary and metabolized 3,000 calories in a day, the amount he needed dropped to I think about 10,000 IU.

Since it seems most people here and the forum have relatively low metabolic rates, and can metabolize only 1,500 to 2,000 calories a day without gaining fat, there will likely be a smaller therapeutic window. For this reason, you should experiment cautiously, and try to increase your metabolic rate.

answered Mar 9, 2015 by visionofstrength
edited Mar 9, 2015 by visionofstrength

The obese subgroup probably had a high prevalence of hypothyroidism. Still 25000 IU, which is much more than you would suggest for those individuals, increased their T3 and decreased TSH.

True, but there are many factors unaccounted for. How many calories was the obese group metabolizing? Some obese people can eat 600 calories a day and remain obese, while others eat thousands of calories a day.

Assuming 25,000 IU to be right, and that Peat's experience were generalizable -- NB: which it is not -- then 25,000 IU might be about right for metabolizing 4,500 calories.

But each person is his or her own crucible and needs to experiment with these things carefully! As a guideline, start low and gradually increase, while looking for signs of orange skin in callouses or elsewhere, which signifies an excess of Vitamin A.

Another factor is Vitamin D status. I've slightly overdone Vit. D supplementation in the past months and need lots of Vit. A now to counteract that (esp. around noon where plasma levels peak).

Right. I've just started doing transcutaneous D3 to see if I can improve my levels within the therapeutic window. Oral delivery of D3 and other hormones seems to me less than optimal, working for a time and then reaching a saturation point, and not working as well.

CB pointed out to me that D3 in MCT can be absorbed through the skin. It's been said that Peat told someone in email he uses D3 on the skin only.

May I ask what symptoms have indicated that you've overdone Vitamin D supplementation in the absence of sufficient Vitamin A, nograde? Or are you basing your assessment on lab values?

mix of symptoms resembling those of hypercalcemia and sarcoidosis. mostly depression, polyuria, sudden onset of anxiety, brainfog, shortness of breath, completely stuffed nose, muscle tension and joint pain. Chief aggravation by anything containing larger amounts of calcium. Quick relief by drinking lots of cola and nutrisorb A.

Interesting! What doses of vitamin D did you take, and how much nutrisorb A to counteract it?

I started with labs that showed 25ng/ml 25(OH)D so I took 20000IU/d for 4 mo after which Vitamin D toxicity symptoms developed. I now need 30000IU/d Vit. A to keep symptoms in check.

Wow thats a hefty dose, why so high?

Jung und dumm, haha. No, seriously ... 20000IU is not that much from what I read. Keep in mind that nowadays Vit. D deficiency treatment is often started with 600000IU (!) "Stosstherapy" and commences with 10000IU/d for long time. Also It helped me tremendously with my IBS in the beginning and I felt no ill-effects. but ... suddenly tides turned, you better not fuck around with such doses for several months ...

Why does cola help, nograde?

I think it's the phosphoric acid ...

Ive never seen anyone receiving 600.000 IE or 10000 IE daily by medical doctors - guidelines recommend 60.000 IE orally once a week for 6-8 weeks if there is overt deficiency in high risk patients (<20 ng/ml), followed by maintenance of 1000-2000 IE. In medium deficiency (20-30 ng/ml), the recommendation is just to take between 800-2000 IE. Sometimes people give 300.000 IE as injection at once, but it is also written in the guidelines that such doses are not fully safe and not equal to a lower doses oral regimen.

I'm curious: Did you got labs to indicate what your levels were when you developed toxicity symptoms? How long do you expect to need so much Vitamin A?
Would blood donation be a way to lower it efficiently? (I'm thinking that it should lower it by about 10% each time, right?)

why in hell peat had to consume so many calories? thats a bodybuilder diet (6k cal)

Please keep in mind that the only larger randomized trial that gave only retinol (25.000 IE retinol per day or placebo for 3.8 years, in 2297 men and women with a mean age of 63 and a history of precancerous or skin cancer lesions), showed a non-signifcant trend of increased mortality risk of +15% in the retinol group (confidence interval 0.81-1.65).

I dont think the safety retinol supplements at such doses has been shown and it may cause more harm than good in the long run.

I also pointed out earlier that there is a potential adverse interaction between smoking and vitamin A, which have been observed in the beta-carotene and beta-carotene plus retinol trials.

answered Mar 10, 2015 by Bukowski
edited Mar 10, 2015 by Bukowski

Agree. I'm sorry I should have said in my answer that I think Peat suggests avoidance of carotene and retinol. He prefers to obtain nutrients from food, for Vitamin A perhaps liver or egg yolks, and not to supplement Vitamin A unless there is some specific need, and in that event, halibut liver oil-derived vitamin A, or retinyl palmitate.