I’ve always been a bit of a fan of Vitamin A but this has grown again in the last year or so, having seen some great responses to short term high dose treatment during active infections or when trying to break a cycle of chronic reinfection. For me, and I think probably for others as well, I previously would get a bit twitchy around even briefly exceeding the UL (upper tolerable limit) for retinol as set by the NHMRC. This was because the potential toxicity of vitamin A, especially for certain vulnerable populations such as children, pregnant women and individuals with liver disease, had been burnt into my brain during my undergraduate training.
As a result, I think many of us have become over-concerned about risks associated with Vitamin A therapy and need to refresh our perspective about the difference between long term high intake above the UL, which does have established risks, and short term equally high doses with have enormous therapeutic potential and extremely low risks if we exclude the most vulnerable patient groups.
We don’t have to look too far for support of this idea, with numerous RCTs employing 5000IU per day ‘until discharge’ to young children inflicted with measles to successfully reduce morbidity and mortality or whopping one off doses of 200,000 IU to treat recurrent urinary tract infections in adults etc.
Of course the therapeutic potential of vitamin A is not limited to an immune one, but it does star in this role. The first identified feature of a vitamin A deficiency was an increased susceptibility to infections and compromised ability to resolve these, regardless of the microbial origin. How often do we see this picture? Frequently…and while our first reflex might be zinc (as of course my bias was for a long time), more often now I am looking for evidence of concurrent or even stand alone suboptimal vitamin A that may also explain this.
In terms of being forgotten, I think many of us need a quick reminder also about the limited distribution of retinol in our diets and that the common exclusion of dairy foods, reduces this further down to a very small handful of foods with any significant amount.
This means that a decent bunch of our patients are going to be at risk of suboptimal vitamin A. Why can’t carotenoids or foods rich in provitamin A always fill this gap?…well you might have to listen to the latest Update in Under 30 to find out! 😉
Vitamin A deficiency is more common than you think and understanding the reasons behind suboptimal intake & status help us to identify those of our patients most at risk. In terms of therapeutic potential, acute high dose retinol supplementation can produce dramatic resolution of infections or break the cycle of recurrent infections in immune compromised individuals. For many clinicians, however, retinol has either been forgotten or become feared due to its toxicity profile. This Update in Under 30 recording, sharpens our focus around not only recognising those who need it but also how to use retinol effectively without the risks.