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Supplements and hair loss
On chronometer.com I noticed that the food I normally eat contains lot of beta carotene. That is why I was looking for supplements that block the conversion of beta carotene to vitamin A. Only found some medicine with such effect. But I did find an article about use of supplements in relation to hair loss. As there are already some topics that describe that low VA is quite beneficial for hair I checked if this article (Diet and hair loss: effects of nutrient deficiency and supplement use) had similar findings.
The article states about vitamin A:
"Vitamin A is a group of compounds including retinol, retinal, retinoic acid, and provitamin A carotenoids. In murine studies, dietary vitamin A has been shown to activate hair follicle stem cells [55], although its role is recognized as complex and “precise levels of retinoic acid are needed for optimal function of the hair follicle” [56].
While deficiency has not been linked to hair loss, high levels of vitamin A have. In fact, one study found that in a mouse AA model, reduction of vitamin A in the diet actually delayed hair loss onset [56].
In humans, hypervitaminosis A may result from over-supplementation and has a strong known link to hair loss with other effects such as skin, vision, and bone changes [4,8]."
That confirms what we already suspected. The interesting thing is that also other common supplements are mentioned like vitamin E that in excess (just 600ie for 28 days) is likely to have adverse effect on hair growth. The group of vit. E volunteers had also significant decreases in thyroid hormone levels. Which is particularly bad (including hair loss & increase of body weight). Supplementation of iron and zinc can be beneficial for hair growth when one is deficient. Some other factors as fatty acids and protein intake are mentioned as well. Excess selenium can cause hair loss too.
As zinc, taurine and vitamin E are used in some studies as kind of antidote against vitamin A be aware of the side effects and better not overdo supplements. In fact I more and more get convinced that we better completely refrain from any supplementation as the food in developed countries already contains an abundance of everything we need to stay healthy. Just eat varied and in moderation.
I think it's futile to attempt to block the conversion. Carotenoids themselves have some of the adverse effects that vitamin A can have and are potentially worse depending on individual responses.