Age and gender-specific effects of metformin (animal research) | Rhonda Patrick

Interesting. Now, if you look at male and female mice that were given metformin, about 100 milligrams per kilogram body weight, which for— that's a human equivalent dose of like 8 milligrams per kilogram body weight. So that translates to something like 660 milligrams for like a 180-pound person. So that given to mice, it decreased the average lifespan of male mice by 13% and increased the average lifespan of female mice by about 4%. Now, the negative effect on male lifespan could actually be dose-dependent. So, there was another study looking at different doses in male mice. So, male mice were given either a 0.1% or a 1% dose of metformin in their diet starting at the age of 50 weeks or something, 54 weeks. Their lifespan, their average lifespan increased at the lower dose.

So, their average lifespan increased by close to 6%. But the high dose, it was toxic. It reduced their average lifespan by like what I mentioned earlier, something between 13 to 14%. So that's something to consider, the dose. Uh-huh. And then also the age that, you know, these animals are given their first treatment. There was another study, and this is in female— a lot of studies have been done in female mice because that was— female mice have been shown to be the most responsive in terms of lifespan-extending effects. And female mice that were given, again, 100 milligrams per kilogram body weight of metformin starting at the age of 3 months, 9 months, or 15 months, the most robust effects happened earlier. So, at 3 months, lifespan was increased by 14%.

If they were given at the age of 9 months, it increased by only 6%. And if they were given it at the age of 15 months, their lifespan, there was no effect, no difference at all. Wow. On average around 2 to 2.5 years. So that's like their average lifespan. So 15 months is a little bit— What do mice typically die of? Just old age? It depends. You know, some of them, they get like lymphomas and yeah, but they do, they die of old age. The reason why I ask is that, you know, some of the life extension things on the human side I've heard have been linked to its ability to prevent certain cancers. Yeah. We'll get to that.

And that's one thing, like mice don't get human types of, I mean, humans get lymphomas and leukemias, but the majority of human cancers are are what's called epithelial-based cancers, not blood-based cancers. They're epithelial-based cancers, meaning they're like solid tumors, you know, prostate cancer, liver cancer, breast cancer, ovarian cancer, right? You know, these, these are all solid tumors. Some of the human studies, which is what you just brought up, I mean, that's, that's kind of like getting to the human data is what's really important. But I wanted to mention that animal study data because it's the variable effects on, you know, depending on gender and dose and time of, administration. I think that's all important stuff to consider, right? And we don't really know why, honestly, why the male mice are so sensitive to dose in terms of their lifespan effects.