Thread: Here's how you calculate the human dosage

Here's how you calculate the human dosage

This webzine often features animal study findings that get adventurous ergonauts itching to try things out on themselves. A toxicologist at the University of Wisconsin published an article in 2008 in FASEB Journal which will be of interest to them. It describes a way to convert doses used in an animal study into doses suitable for humans.

Researchers who test the effect of a substance on lab animals usually measure in mg per kg bodyweight per day. The problem is that hit-and-miss conversions for humans usually end up with unrealistic mega-doses. Shannon Reagan-Shaw, the first author of the article we've ransacked here, uses the media hype surrounding resveratrol as an example. If you convert the doses used in the positive animal studies in this way to humans, as has been done in some critical articles, then you arrive at 1300 mg resveratrol per day. That’s impractical, unaffordable and may well be dangerous too.

And, Reagan-Shaw adds, it's also scientifically incorrect. If you want to calculate the human equivalent from a dosage used in an animal study, you have to also take metabolism into account. And there are formulas for this. If you use them, then for resveratrol, instead of a dose of 1344 mg/day you arrive at 109 mg/day for an adult weighing 60kg.

We've reproduced the formula that Reagan-Shaw prefers below. You have to enter the data from the table below into the formula. And of course, you have to add the dose given in the animal study.





So if it's a study that used mice, you have to take the dose used – in mg/kg/day – and first multiply it by 3 and then divide the result by 37. A short cut is to divide the dose by 12.3. For rats you have to divide by 6.2.

We at ergo-log use an even simpler and safer rule of thumb for rats and mice, which we got from product designers in the functional foods industry. We divide the dosage by 15 to get the lower boundary. And we divide by 10 to get the upper boundary.

"It's a bucket method, but it turns out to be just as effective in practice", reported a researcher who works for an influential food company. "We've noticed that rats in particular break down substances faster than the formulas suggest. If we are going to do human studies and need to weigh up effectiveness versus safety, after the event we notice that the doses are pretty much the same whether you calculate using the simple rule of thumb or using all kinds of sophisticated formulas."

Source:
FASEB J. 2008 Mar;22(3):659-61.