The Hot Spring

In January of 2024, I took my friend out to El Dorado Hot Springs in Tonopah—about an hour west of Phoenix, out where the desert gets serious and the cell signal does not. The water comes up at about 104 degrees, no sulfur smell, and if you sit in it long enough you start to feel like your skeleton is optional.

At the time I was dealing with a mild but persistent depression. I was coming to grips with the fact that I was facing the final years of my life and that my right hip, despite surgery, was making mobility an increasingly theoretical concept. The combination of mortality and immobility is not a cheerful one. I was not in crisis. I was just…gray. Everything was gray. The kind of gray where you can still function and still laugh at jokes but the laughter does not quite reach the place where joy lives.

My friend and I were soaking and talking about the supplements I was taking—a conversation that happens naturally when one person is seventy-two and the other is studying pharmacology. I ran down my list: the usual suspects, including a "Super" B Complex that I was quite proud of, because it said "Super" right there on the label and I am nothing if not a sucker for anything sounding even faintly Kryptonian.

He looked at me the way a mechanic looks at someone who just said they changed the oil but forgot the filter. "You're not taking methyl folate?"

"I'm taking a B Complex," I said. "It's got all the B vitamins in it. It says so on the bottle."

And then he explained, patiently, through the rising steam, why that was not the same thing at all.

The Problem With Folic Acid

Most B-complex supplements and multivitamins contain folic acid. Folic acid is the synthetic form of vitamin B9, and it is cheap to manufacture, which is why it shows up everywhere. The problem is that your body cannot use folic acid directly. It has to convert it, through a multi-step enzymatic process, into L-methylfolate—also called 5-MTHF—which is the form that actually does the work.

This conversion depends on an enzyme called MTHFR. And here is where genetics enters the chat: roughly 40% of the population carries one or more variants of the MTHFR gene that impair this conversion. Some people convert folic acid reasonably well. Some convert it poorly. Some barely convert it at all. And unless you have had genetic testing, you have no idea to which group you belong.

Even if your MTHFR enzyme works perfectly, the conversion efficiency decreases with age. So a B-complex supplement that provided adequate folate when you were thirty may be doing almost nothing for you at seventy. You are swallowing a check your body cannot cash.

What Methyl Folate Actually Does

L-methylfolate is the biologically active form of folate. It skips the entire conversion process—no MTHFR required, no enzymatic bottleneck, no genetic lottery. You take it, your body uses it. Period.

What it does, once it gets where it is going, is participate in something called the methylation cycle. This is one of those biochemical processes that sounds abstract until you learn what it produces. The methylation cycle converts homocysteine into methionine, which in turn produces SAMe (S-adenosylmethionine)—and SAMe is the molecule your brain needs to synthesize serotonin, dopamine, and norepinephrine.

Those three neurotransmitters are, collectively, your mood. Serotonin is the one that keeps you from feeling like the world is ending. Dopamine is the one that makes you want to get out of bed and do something. Norepinephrine is the one that helps you focus and respond to the world around you. If any of them runs low, you feel it. If all three run low, you feel like I felt: gray.

Clinical studies back this up. Between 15 and 38 percent of adults diagnosed with depression have low folate levels. When L-methylfolate was added to standard antidepressant treatment in randomized trials, the response rate more than doubled—32 percent versus 15 percent with a placebo. The pharmaceutical industry noticed: there is a prescription product called Deplin that is nothing more than L-methylfolate at 15 milligrams a day, marketed specifically as an adjunct for treatment-resistant depression.

Fifteen milligrams. Which is exactly the dose I take.

Two Days

I ordered methyl folate from Amazon that evening—still slightly pruney from the hot spring—and started taking 15 mg a day when it arrived. I figured that if I had been running low for years, I might as well make up for lost time. And since B vitamins are water-soluble, whatever my body did not need would simply leave by the usual route. You cannot really overdose on folate; your kidneys handle the excess the way a bartender handles a customer who has had enough.

My friend had not specified why I should be taking it. He just seemed to think it was an obvious gap in my regimen, the way a dentist might notice you are not flossing. He did not promise it would fix my mood. He did not promise anything.

Within two days, the gray began to lift.

It was not dramatic—not the way the glutathione hit, where I could point to a single conversation and say there, that is where it changed. This was more like waking up one morning and noticing that the world had color in it again. Not bright, exuberant, dancing-in-the-streets color. Just…color. The sky was blue instead of gray. The dogs were funny instead of just there. I wanted to write something, which I had not wanted to do in months.

The depression did not vanish. But it retreated from the foreground to the background, from a weather system to a memory of one. I could function again. I could want things again. That is a distinction people who have never been depressed do not always understand: depression does not just make you sad. It makes you not want. Not want to eat, not want to move, not want to talk, not want to want. Getting the wanting back is everything.

Why It Probably Works

I am not a biochemist, and I did not get genetic testing to confirm whether I carry an MTHFR variant. But the circumstantial case is strong. I am seventy-five. I had been taking folic acid in a B-complex for years, which means I thought I was getting adequate folate. I was not. Either my MTHFR conversion was impaired by genetics, by age, or by both—and my brain was slowly starving for the raw material it needed to make the neurotransmitters that keep the lights on.

When I bypassed the broken conversion pathway by taking the active form directly, my brain finally got what it had been missing. The serotonin came back. The dopamine came back. The norepinephrine came back. And the gray went away.

This is not a miracle. It is plumbing. The pipe was clogged, and methyl folate went around the clog.

I still take 15 mg of methyl folate every day. My mood is stable in a way it has not been in years. I still have bad days, because I am a human being living in a country that currently seems determined to test the limits of my patience, but the bad days are bad days—not bad months, not bad seasons, not the kind of ambient grayness that makes you forget what sunlight feels like.

The only way my mood could improve further would be if I won the lottery on the day of Trump's funeral.

But short of that, methyl folate will do.