Vitamin A Toxicity

How Vitamin A Works

Vitamin A provides a host of benefits for young and old alike. These benefits include, but are not limited to, vital bodily functions like cardiovascular health, bone metabolism, embryonic development in pregnant women and maintaining genetic integrity. It is also a key vitamin for maintaining healthy eyesight and good skin, and it works as an overall immune system enhancer.

It comes in two forms; preformed vitamin A, and provitamin A, a precursor that becomes vitamin A in the body once ingested. This is where you find substances like beta-carotene, the primary source of vitamin A in carrots. For the former, meats and meat products like liver pack quite a vitamin A punch, as do fish, eggs and most dairy products.

Vitamin A Is Fat-Soluble

Some vitamins, like B and C, are water-soluble and basically flush right out if you ingest too much. In essence, that's vitamin-fortified urine you're letting out, which explains why paying good money on megadoses of vitamins is foolish but not really harmful.

Unfortunately, the same does not hold true for fat-soluble vitamins like vitamin A. This type of vitamin "piggy-backs" on fat molecules on their way into your system, making them that much more difficult to manage. For people who eat "Frankenfat" products, like the infamous Olestra potato chips, it means vital vitamins attach to fat -- that is then rushed through the system and into the toilet, creating a deficiency situation.

On the flip side, if you eat normal fat and happen to take in too much vitamin A, the body can't just flush it out as needed. Instead, it accumulates and starts getting toxic once you've jammed enough in there. As always, moderation in everything tends to yield the best long-term results for your health.

Signs Of Vitamin A Toxicity

Some signs and conditions that can develop as a result of either acute vitamin A poisoning (doses of 25,000 IU/kilogram of bodyweight) or cumulative overdosing:

• Nausea
• Vomiting
• Jaundice
• Abdominal pain and cramping
• Mood swings and irritation
• Radically decreased appetite
• Persistent tiredness

The severity of vitamin A toxicity depends on a lot of factors, such as body size and pre-existing conditions. For example, those with already weakened livers tend to fare much worse than otherwise healthy people. It is also worth noting that pregnant women should be especially careful not to overdo the vitamin A, since studies have shown that developing children are particularly vulnerable to the negative effects of vitamin A overdosing.

Another point of note is that these symptoms are primarily the result of the preformed vitamin A. Provitamin A is largely spared from ill effects, although it's the beta-carotene found in carrots that is responsible for the peculiar orange-tinted look people who jump on fad diets heavy on carrots get.

Finally, you may hear about a new breed of engineered vitamin A that is water-soluble. This would seem like great news, except that so far it has turned out significantly more toxic than the regular, fat-soluble version of vitamin A. In fact, a recent study showed children supplemented with water-soluble vitamin A were twice as likely to develop asthma and other allergies.