Came across an interesting study about Vitamin A and energy metabolism in rats. I’ll admit I’ve never paid much attention to my Vitamin A intake…guess I should start.
Vitamin A Deficiency Increases Protein Catabolism and Induces Urea Cycle Enzymes in Rats.
" Chronic vitamin A deficiency induces a substantial delay in the rates of weight and height gain in both humans and experimental animals. This effect has been associated with an impaired nutrient metabolism and loss of body protein. Therefore, we analyzed the effect of vitamin A deficiency on endogenous proteolysis and nitrogen metabolism and its reversibility with all-trans retinoic acid (RA). Male weanling rats, housed in pairs, were pair-fed a vitamin A-deficient (VAD) or control diet until they were 60 d old. A group of deficient rats were further treated with daily intraperitoneal injections of all-trans RA for 10 d. Final body and tissue (i.e. liver and heart) weights were significantly lower and tissue:body weight ratios were similar in VAD rats and in controls. Conversely, the epididymal white fat:body weight ratio and the plasma concentrations of alanine aminotransferase and adiponectin were significantly higher in VAD rats, which also had hepatic macrovesicular lipid accumulations. Plasma and gastrocnemius muscle 3-methylhistidine, urine nitrogen, and plasma and urine urea concentrations were all significantly higher in the VAD group. The expression of the genes encoding urea cycle enzymes and their activities increased in VAD livers. These changes were partially reverted by all-trans RA. We propose that fuel partitioning in vitamin A deficiency may shift from fatty acids to protein catabolism as an energy source. Our results emphasize the importance of vitamin A on the energy balance control system and they provide an explanation for the role of vitamin A in protein turnover, development, and growth. "
Link
http://jn.nutrition.org/cgi/content/short/140/4/792?rss=1
I know my dog is a lot healthier when I feed her canned pumpkin mixed with her food (pumpkin has vit a through the roof). it was recommended by the vet for weight loss and it works. Not sure if it’s related whatsoever, but i thought i’d share that little tid bit.
[quote]Fulford wrote:
Came across an interesting study about Vitamin A and energy metabolism in rats. I’ll admit I’ve never paid much attention to my Vitamin A intake…guess I should start.[/quote]
If you include carrots in your diet then you should be fine… Also high levels of vitamin A are toxic so don’t get overzealous.
[quote]angus_beef wrote:
[quote]Fulford wrote:
Came across an interesting study about Vitamin A and energy metabolism in rats. I’ll admit I’ve never paid much attention to my Vitamin A intake…guess I should start.[/quote]
If you include carrots in your diet then you should be fine… Also high levels of vitamin A are toxic so don’t get overzealous. [/quote]
To clarify - Remember the difference between retinol (preformed vit A) and carotenoids (provitamin A from foods). You would be fine with carrots, pumpkin, spinach, etc, at nearly any dose, as you rbody regulates the conversion process but multi-vitamin pills or other supplements with retinol, you should limit your dose.
[quote]angus_beef wrote:
If you include carrots in your diet then you should be fine… Also high levels of vitamin A are toxic so don’t get overzealous. [/quote]
Not vitamin A in the form of beta-Carotene I think.
[quote]plateau wrote:
[quote]angus_beef wrote:
If you include carrots in your diet then you should be fine… Also high levels of vitamin A are toxic so don’t get overzealous. [/quote]
Not vitamin A in the form of beta-Carotene I think.[/quote]
Correct, i was referring to supplementation.
[quote]angus_beef wrote:
[quote]plateau wrote:
[quote]angus_beef wrote:
If you include carrots in your diet then you should be fine… Also high levels of vitamin A are toxic so don’t get overzealous. [/quote]
Not vitamin A in the form of beta-Carotene I think.[/quote]
Correct, i was referring to supplementation. [/quote]
Not to be a dick, I just want to clarify (if it was not already made clear) that many supplementation forms are actually beta-carotene (provitamin - your body will decide how much to convert), although many are retinol (preformed) as well. If you have a quality multi, caretenoids/betacarotene is something to check for. If it says anything like retinol, retinyl ester, and or retinyl acetate or palmitate, then you have a product that is of concern since you’ll have to ensure you don’t ingest too much preformed Vit A from the multi when combined with other sources.
If you’re unsure about whether the form is your multivitamin/mineral or whatever is preformed or provitamin, either google it or check here: Vitamin A - Wikipedia Retinol - Wikipedia
More info here: Vitamin A | Linus Pauling Institute | Oregon State University