Luck based medicine: inositol for anxiety and brain fog

Link post

Summary: Do you have weird digestive symptoms and anxiety or depression? Consider trying inositol (affiliate link), especially if the symptoms started after antibiotics.

Epistemic status: I did some research on this 10 years ago and didn’t write it down. In the last nine months I recommended it to a few people who (probably) really benefited from it. My track record on this kind of suggestion is mixed; the Apollo Neuro was mostly a dud but iron testing caught a lot of issues.


Inositol is a form of sugar. It’s used in messaging between cells in your body, which means it could in theory do basically anything. In practice, supplementation has been found maybe-useful in many metabolic and psychiatric issues, although far from conclusively.

There are a few sources of inositol: it’s in some foods, especially fruit. Your body naturally manufactures some. And some gut bacteria produce it. If your gut bacteria are disrupted, you may experience a sudden drop in available inositol, which can lead to a variety of symptoms including anxiety and depression.


Inositol deficiency (probably) hit me hard 9 years ago, when I went on a multi-month course of some very hardcore antibiotics to clear out a suspected SIBO infection.

Some background: My resistance to Seasonal Affective Disorder has been thoroughly tested and found triumphant. At the time I took those antibiotics I lived in Seattle, which gets 70 sunny days per year, concentrated in the summer. This was a step up from my hometown, which got 60 sunny days per year. I briefly experimented with sunshine in college, where I saw 155 sunny days per year, a full 75% of the US average. The overcast skies never bothered me, and I actively liked Seattle’s rain. So when I say I do not get Seasonal Affective Disorder or light-sensitive depression, I want you to understand my full meaning. Darkness has no power over me.

That is, until I took those antibiotics. I was fine during the day, but as soon as sun set (which was ~5PM, it was Seattle in January) I experienced crushing despair. I don’t know if it was the worst depression in my life, or just the most obvious because it went from 0 to doom 15 minutes.

Then I started taking inositol and the despair went away, even though I was on the antibiotics for at least another month. After the course finished I took some probiotics, weaned off the inositol, and was fine.

About six months ago, my friend David MacIver mentioned a combination of mood and digestive issues, and I suggested inositol. It worked wonders.

He’s no longer quite so deliriously happy as described in the tweet, but still describes it as “everything feels easier”, and every time he lowers his dose things get worse. So seems likely this is a real and important effect

He’s also tried probiotics. It took several false starts, but after switching brands and taking them very consistently he was able to lower his dosage of inositol, and the effects of going off it are less dramatic (although still present).

He has a fairly large twitter following, so when he tweeted about inositol he inspired a fair number of people to try it. He estimates maybe 50 people tried it, and 2-5 reported big benefits. So ballpark 4-10% response rate (of people who read the tweet and thought it looked applicable). And most people respond noticeably to the first dose (not me, I think it took me a few days, but most people), so it’s very easy to test.

A second friend also got very good results, although they have more problems and haven’t tested themselves as rigorously as David, so causality is more questionable.

Fun fact: because inositol is a cheap, white, water soluble powder it’s used as a cutting agent for multiple street drugs. It’s also the go-to substitute for cocaine in movies. So if cocaine, heroin, or meth have weirdly positive effects on you, might be worth checking out.


Anything with a real effect can hurt you. Even that totally safe magic bracelet I recommended maybe gave someone nightmares. But as these things go, inositol is on the safer end to experiment with. The fact that it’s both a natural food product and produced endogenously gives you good odds, especially compared to cocaine. OTOH the fact that it has a lot of sources makes it harder to dose – after a few months David found that his initial dose was too high and induced brain fog, and he needed to lower it.

I have a vague impression that quality isn’t an issue with inositol the way it is with some vitamins, so I just linked to the cheapest ones.

In terms of dose: standard dosage is 0.5- 2g/​day. David started at high end of that but is now down to 0.5-1g. I can’t remember what I did. If you try it, start small and experiment.

If you do try it, I’d love if you filled out this form letting me know how it went.

Thanks to David Maciver for sharing his data.