Sunday, March 15, 2009

Vitamin A

Vitamin A comes in both fat-soluble (from animal sources) and water-soluble (from plant sources) varieties. Lipid-soluble vitamin A is stored in fat cells and in the liver and excess can lead to toxicity whereas water-soluble provitamin A is more easily excreted. Vitamin A can be found as retinol (an alcohol), retinal (an aldehyde), or retinoic acid (RA). Deficiencies or excesses of Vitamin A can be detrimental to neurological health.

Isotretonoin, a synthetic retinoid used to treat severe acne (and other dermatological symptoms), can cause psychiatric side effects including depression and suicidality, especially in teens who are more likely to be taking the drug. A recent study (1) which reviewed publications linking psychopathology to isotretonoin showed many studies with convincing evidence of the link, though with flawed methodologies. Other studies showed no correlation. The author does point out the obvious fact that a dermatological condition can also be a cause of psychiatric symptoms.

It is believed that isotretonoin’s effect on psychopathology is through its many effects on neurotransmitter systems (2). The pathways are complicated, but evidence indicates a correlation between RA pathways and Alzheimer’s, schizophrenia, and the serotonergic system (sleep and mood).

The recommended daily intake of Vitamin A is 900 – 3000 µg for adult males and 700 – 300 µg for adult females. Some sources of vitamin A are liver (6500 µg and gross), carrots (835 µg), sweet potatoes (709 µg, I still don’t know the difference between a sweet potato and a yam), spinach (496 µg), and broccoli (31 µg, the leaves have much more content, 800 µg).

References: 1, 2

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