Absorption of Vitamin A

Original question: ‘I constantly have a problem with the palms of my hands appearing to be somewhat yellowish. No one has been able to tell me why this occurs as I do not drink excessive carrot juice or any other orange/yellow products. Why?’

I would suspect that the yellowish pigment is related to an excess beta-carotene. Beta-carotene is one of a class of compounds known as caroteniods, of which some act as precursors to vitamin A. Beta-carotene is converted to vitamin A in the upper intestinal tract by fat spitting enzymes and bile salts. This process is stimulated by thyroxine and some people who may be lacking in this hormone and have under active thyroid glands (hypothyroidism) may have trouble converting beta-carotene to vitamin A. If beta-carotene is unchanged, then some will be absorbed into fat tissues and may make the skin appear yellowish.

Diabetes is another factor that may interfere with beta-carotene conversion. If the situation continues to occur then I would suggest you have checks for both thyroid function and blood sugar metabolism. If converted correctly to Vitamin A, then this vitamin is normally stored in the liver.

Note that an excessive intake of beta-carotene containing foods (carrot juice, papaya) may cause a short-term yellowing of the skin, usually noticeable on the palms of the hands, simply because the intake is too much to be converted all at once, but this yellowing will disappear over a day or so and does not indicate a metabolic disturbance.