Vitamin A is a fat-soluble vitamin that directly affects muscle growth. The process on hypertrophy, muscle protein synthesis, the multiplication of new cells, requires vitamin A.

Vitamin A deficiency affects iron mobilization and impairs red blood cell synthesis, leading to a low red blood cell count. This negatively affects your endurance as well as recovery ability between sets. In short, a vitamin A deficiency promotes fatigue.

Vitamin A from animal sources is directly absorbed, utilized and stored, whereas vitamin A from plants (beta-carotene), first needs to be converted to retinol by the liver. Our bodies aren’t very good with this conversion and the ratio is about 6:1 or even worse. Under conditions of stress and disease, that ratio is further increased or even completely hindered.

Retinoic acid (the active form of vitamin A) binds to RAR (retinoic acid receptor) and RXR (retinoic x receptor), which are receptors that belong to the super-family of thyroid and steroid receptors. Vitamin A has a direct impact on thyroid and steroid production. It also works in synergy with steroid hormone – vitamin D – to be fully enabled to exert powerful actions. As vitamin D levels increase, so does vitamin A requirements. Elevated vitamin D can deplete vitamin A, if inadequate vitamin A is consumed through the diet.

Vitamin A for fat loss and muscle growth

1) Retinol is found in adipose tissue, where it is shown to inhibit adipogenesis (the formation of fat cells).

2) Vitamin A, as all-trans retinol, has been found to activate and multiply the UCP1 gene in adipose tissue (which increases thermogenesis and energy expenditure).

3) Vitamin A also lowers cortisol (by inhibiting the enzyme reduces 11β-HSD1 activity which converts cortisol into its active form), which significantly lowers bodyweight and visceral fat, because cortisol promotes the storage of fat around the midsection (R). Cortisol is also catabolic and is best kept low.

3) A deficiency in vitamin A leads to lower immunity, slows wound healing as well as hindered muscle protein synthesis (R). Adequate levels will ensure that muscle protein synthesis signaling is optimal and that you recover faster after injuries and training.

4) Retinoic acid activates the retinoic acid receptor (RAR) which induces activates phosphoinositide 3-kinase (PI3K) which is involved in muscle protein synthesis and ultimately – muscle growth.

5) A vitamin A deficiency leads to significantly low testosterone and growth hormones, as if in a state of castration (R). Retinoids also play a role in the maintenance and regulation of Leydig cell function and are able to stimulate testosterone synthesis and also increase LH receptor density and sensitivity (R).

6) Adequate amounts of retinoic acid increases testosterone levels, IGFbinding protein 4 (IGF transporter) and steroidogenic acute regulatory protein (StAR – which transports cholesterol into the gonads to be converted to testosterone).

7) Vitamin A increases nocturnal growth hormone in vitamin A deficient boys via the cyclic AMP pathway, and the greatest spike was seen after a 100nM (10 000IU) retinoic acid dose (R). The fastest growth occurs during sleep and that’s where nocturnal growth hormone is so important (R).

8) Vitamin A deficiency interfered with the pituitary-thyroid axis by: 1) increasing the synthesis and secretion of thyroid-stimulating hormone (TSH) by the pituitary gland, 2) increasing the size of the thyroid gland, 3) reducing iodine uptake by the thyroid gland and 4) impairing the synthesis and iodination of thyroglobulin (precursor to thyroid hormones), thus leading to hypothyroidism.

Vitamin A is positively associated with triiodothyronine (T3) and free T3 index (FT3I), which indicates better conversion from thyroxine (T4) to T3 (R). Thyroid hormones are essential for building muscle and staying lean. Read more here on thyroid and building muscle.

Vitamin A’s demands in the body increase when:

  1. Exercising intensely
  2. Eating more protein
  3. You want to increase testosterone production
  4. You want to improve certain health aspects, such as dandruff, vision, skin, etc…
  5. Vitamin D levels increase

Zinc, molybdenum, vitamin B2 and taurine is necessary for the proper handling of vitamin A in the body.

Excellent sources of retinol include livercod liver oil, and animal fat including dairy and eggs.

Get your vitamin A extract from a natural source for maximal benefits.

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Published by Hans Amato

Hi, I'm Hans and I'm a physique, strength and nutrition specialist/coach. My passion is building the best physique naturally (both functional and super strong) and enabling others to achieve their dream physique and health goals as well. Nothing is impossible if you set your mind and heart to it - not even you're "genetic limit" will be able to stop you then.

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  1. Hiya, I am really glad I have found this information. Today bloggers publish just about gossips and web and this is actually annoying. A good website with interesting content, this is what I need. Thank you for keeping this site, I will be visiting it. Do you do newsletters? Cant find it.


    1. Hey man. Thank you for your positive feedback. Sorry I don’t do newsletters at the present time, although you can always follow this blog and receive my new blogs via email.


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