Powerful Betaine Benefits (as Trimethylglycine) and Reviews

Written and medically reviewed by Heidi Moretti, MS, RD, CLT — Registered Dietitian and Certified LEAP Therapist with 25+ years of clinical experience in functional nutrition and gut health. See full bio.

TMG (betaine) benefits are wide-ranging: it’s a natural compound that’s central to methylation and metabolism, with effects that reach the liver, the gut, the brain, and the muscles. This post has been fully updated for 2026 with new clinical trial data on betaine and fatty liver disease, new research on how gut bacteria may unlock some of betaine’s muscle benefits, personal review notes, and reader reviews.

In this post, learn about the many fascinating betaine benefits, potential side effects, and how to use betaine — plus a closer look at who stands to benefit the most from it.

Table of Contents

• What Is Betaine (Trimethylglycine)?
• How TMG (Betaine) Benefits the Body
• The Methylation Pathway: How Betaine Actually Works
• Betaine for the Brain and Mood
• Betaine Benefits for the Heart
• Betaine Benefits for MTHFR Gene Variants
• Betaine for Exercise Performance
• Betaine Benefits for Gut Health
• Betaine, Testosterone, and Cortisol
• Betaine for Liver Health: The New MASLD Research
• Betaine Safety and Side Effects
• Betaine Supplementation and Dosing
• Who Benefits the Most From TMG?
• Betaine Reviews
• FAQs

What Is Betaine (Trimethylglycine)?

Betaine, or trimethylglycine (TMG), is the amino acid glycine attached to three methyl groups, and it’s naturally present in the body. It’s found in foods as well as in supplement form. Originally discovered in beets (hence the name “betaine”), it’s also found in foods like seafood and whole grains.

There are two kinds of betaine supplements: betaine anhydrous and betaine HCl. Betaine HCl is primarily used to support digestive function and stomach acid, while betaine anhydrous is used for methylation support, body composition, and lowering the inflammatory marker homocysteine. This post is about betaine anhydrous — simply betaine without the water molecule.

TMG (betaine) benefits are largely tied to its ability to lower inflammatory compounds in the body while supporting weight management and lean muscle.

How TMG (Betaine) Benefits the Body

As a methyl-donating amino acid, TMG’s actions in the body are numerous. Here are its main mechanisms for supporting overall health:

Methyl donor for SAMe production — Every split second, your body needs methyl donors to make methionine and s-adenosylmethionine (SAMe). These compounds support overall health, mood, and focus, and SAMe promotes heart health too.

Cellular hydration and osmoregulation — TMG keeps the water balance inside cells more stable, which helps cells stay resilient under metabolic and physical stress.

Antioxidant and anti-inflammatory action — TMG acts as a potent antioxidant that helps lower inflammatory compounds in the body.

Lowers homocysteine — One of betaine’s most important benefits is reducing homocysteine, since elevated homocysteine is linked to a higher risk of heart disease, stroke, osteoporosis, dementia, and cancer.

Improves body composition — Numerous studies show betaine helps reduce body fat and promotes lean muscle mass, while also increasing muscle strength alongside exercise.

Supports gut lining repair — Betaine reduces gut toxins like lipopolysaccharide (LPS) and protects intestinal cells from damage. It also promotes a healthy gut microbiome, which in turn may help protect the liver via the gut-liver axis.

May reduce insulin resistance — While more research is needed, TMG supplements may improve fasting blood sugar and insulin sensitivity for people managing metabolic dysfunction.

The Methylation Pathway: How Betaine Actually Works

Understanding betaine’s benefits gets a lot easier once you can see where it sits in the body’s methylation cycle. Betaine donates a methyl group to homocysteine, converting it into methionine — the same pathway that ultimately produces SAMe, the compound behind so much of betaine’s mood, liver, and cardiovascular support.

Betaine essentially provides a backup route to make methionine when the primary folate/vitamin B12-dependent pathway isn’t working efficiently — which is exactly why it tends to matter most for people with MTHFR gene variants.

Betaine for the Brain and Mood

Betaine provides the nutrient trimethylglycine, which enhances SAMe production for healthy mood, provides crucial methyl groups for DNA, brain neurotransmitters, melatonin, and myelin production, and helps cells regulate their water content.

Betaine is also chemically similar to the mood-supporting nutrient SAM-e, which has been clinically studied for improving mood and reducing anxiety. When SAMe is combined with betaine, some research suggests it works even better — an add-on trial comparing SAMe plus betaine to amitriptyline in people with mild depression found the combination well tolerated, with the betaine likely helping to conserve the body’s own SAMe supply.

Newer preclinical research has also shown betaine can calm neuroinflammation by inhibiting the NLRP3 inflammasome pathway, which is one proposed mechanism behind its mood and cognitive benefits — though this work is still in the animal-study stage and shouldn’t be over-interpreted for humans yet.

Using betaine for mood likely works for some people as a stand-alone, because betaine helps the body make its own SAMe. Many reviewers are surprised at how quickly their mood and focus improve with this supplement. While more clinical research needs to be done, there’s little downside to trying TMG to see if it helps you feel better.

Personally, betaine helped my mood and mental calm within about 20 minutes of taking it, and it continues to help me every day. Some people also report it helping with symptoms associated with autism spectrum traits and oppositional defiant behaviors, and many people feel noticeably calmer taking TMG.

That said, betaine is likely to help the most for people who have under-methylation issues, such as those with MTHFR gene variants. About half of people carry some version of this variant, so TMG is likely to help a meaningful portion of the population.

Regardless of genetics, TMG is neuroprotective, so it’s likely to support at least some aspects of brain health for most people, partly by dampening inflammation in the brain.

Find a betaine (TMG) supplement on Amazon

Betaine Benefits for the Heart

Betaine is healthy for the heart because it helps lower homocysteine levels. By lowering homocysteine levels, betaine may reduce the risk of heart failure, atherosclerosis, venous thrombosis, and stroke.

Early animal research suggests betaine may reduce heart-failure risk related to pulmonary hypertension as well. That said, large-scale human clinical trials on betaine’s direct cardiovascular outcomes are still lacking, so this remains a promising — not proven — area.

Related Post: 7 Nutritional MTHFR Supplements That Changed My Life

Betaine Benefits for MTHFR Gene Variants

Many people carry a variant of the MTHFR gene (methylenetetrahydrofolate reductase). Research estimates that at least half of people carry some version of this variant. People with MTHFR variants have an increased likelihood of cardiovascular disease, inflammation, and diabetes, and may have a higher risk of fatty liver disease (now called MASLD — see the updated liver section below) and low bone density.

Having an MTHFR variant also increases the risk of mental health challenges such as depression, anxiety, autism-spectrum traits, and bipolar disorder.

Treating depressive symptoms in people with MTHFR variants using other methyl donors — like natural folate (not folic acid), vitamin B6, and vitamin B12 — has been shown to reduce depressive symptoms as well as homocysteine levels. This is a strong argument for a more personalized, precision-nutrition approach.

More research is needed that looks specifically at betaine in people with MTHFR variants, but mechanistically it makes sense that it would help, since betaine provides an alternate methylation route.

Of note: folic acid is not well utilized by people with MTHFR polymorphisms — natural folate should be used instead.

Case reports of early treatment in children with severe MTHFR variants using betaine showed improved mental and physical development.

Related reading: The Best Inositol Supplement Types + Its Many Proven Benefits

Betaine for Exercise Performance

Research shows betaine may improve body composition and exercise performance by helping people reduce body fat. Body fat was also reduced in another study where betaine was combined with resistance training.

Another study found betaine increased the number of repetitions performed in exercises like the bench press, squat, and deadlift. Betaine has also been used to improve cycling performance and peak power output.

Betaine may support exercise performance partly by helping the body burn fat while limiting excess fat storage. TMG also appears to reduce post-exercise cortisol and increase growth hormone and other anabolic compounds like IGF-1.

New for 2026: a mechanistic study published in Gut Microbes found that gut bacteria — specifically Akkermansia muciniphila — help coordinate betaine’s effect on skeletal muscle. In that research, betaine and Akkermansia together promoted a shift toward more fatigue-resistant, slow-twitch muscle fibers by influencing an RNA-methylation mark on a key muscle gene (Myh7). It’s early, mechanistic work rather than a human performance trial, but it helps explain why betaine’s exercise benefits may vary from person to person depending on their existing gut microbiome composition.

Betaine Benefits for Gut Health

Betaine’s benefits likely extend to gut health as well. Several studies show TMG supplements help improve the microbiome while dampening inflammation and healing the gut lining in animal research.

Fascinatingly, betaine helps increase anti-obesity probiotic strains including Akkermansia muciniphila, Lactobacillus, and Bifidobacterium. Gut resilience may also improve with betaine supplementation by reducing inflammation, which may in turn lower the risk of inflammatory bowel conditions like ulcerative colitis — though more research is still needed here.

A 2025 mechanistic study went a step further, showing that Akkermansia muciniphila essentially “coordinates” some of betaine’s downstream effects — including the muscle-fiber changes discussed in the exercise section above — via an epigenetic mark called m6A RNA methylation. This is one of the clearest pieces of evidence yet that betaine’s benefits aren’t purely a “take it and it works” story; your existing gut bacteria may partly determine how much you benefit.

Betaine, Testosterone, and Cortisol

An interesting benefit of betaine supplements is that they help increase testosterone levels in CrossFit athletes and improve the testosterone-to-cortisol ratio. The impact on testosterone was striking: betaine increased testosterone levels by 79% in that study. This wasn’t an isolated finding — another study in young soccer athletes found testosterone levels 75% higher than placebo with betaine doses of 2.5 grams per day. In both studies, athletes also reported better strength and endurance.

Betaine for Liver Health: The New MASLD Research

Betaine (TMG) has long been considered good for the liver because it’s an antioxidant that may reduce fat buildup in the body, including the liver. It may help both alcohol-related liver conditions and what used to be called nonalcoholic fatty liver disease — now renamed MASLD (metabolic dysfunction–associated steatotic liver disease) under a 2023 international nomenclature consensus, because “nonalcoholic” and “fatty” were considered stigmatizing and imprecise terms. If your chart used to say NAFLD or NASH, it likely now reads MASLD or MASH (metabolic dysfunction-associated steatohepatitis) — same underlying condition, more accurate name.

Historically, the best human evidence for betaine and liver health came from older trials using high doses (around 20 grams per day for up to a year), which reduced liver injury markers but caused enough GI discomfort that many people struggled to stay on it long term.

That changed with a set of pilot trials published in Hepatology in 2025–2026. Researchers tested much lower betaine doses — 8 g, 4 g, 2 g, and 1 g per day — in adults with clinically diagnosed, non-cirrhotic MASLD and elevated ALT (over 75% also had steatohepatitis by advanced biomarker scoring). Doses of 8 g, 4 g, and 2 g per day over 12–24 weeks significantly reduced ALT, AST, and other blood-based markers of liver injury (including cytokeratin-18 and pro-C3, both markers used to track liver fibrosis risk). The 1 g/day dose did not show a significant benefit. Notably, only about 35% of participants reported any GI symptoms, and they were mild and short-lived — a marked improvement over the older 20 g/day protocol, where GI side effects were common enough to cause dropouts.

Here’s how the liver-enzyme improvement compared across doses in that research:

The practical takeaway: for people managing MASLD, betaine appears to work at meaningfully lower — and better-tolerated — doses than researchers previously assumed, though a 1 g/day “maintenance” dose on its own doesn’t appear to be enough. As always, liver enzyme changes and dosing decisions should be made with your physician or dietitian, especially if you’re managing existing liver disease.

Related reading on liver support: Fascinating Ox Bile Benefits + Best Brands and The 11 Potential TUDCA Benefits That Are Powerful.

Betaine Safety and Side Effects

Betaine (TMG) is a very safe supplement and is generally recognized as safe (GRAS) by the FDA. Some people experience GI side effects such as nausea, vomiting, diarrhea, indigestion, and bloating, and these are more common at higher doses (3–20 grams per day) — which, per the newer research above, may not even be necessary for most people to see a benefit.

Occasionally, people report increased energy that interferes with sleep, which is why taking TMG earlier in the day tends to work best.

Betaine Supplementation and Dosing

Betaine anhydrous dosing in research has historically ranged from 500 mg up to 20 grams per day, depending on the goal (methylation/mood support vs. liver support vs. athletic performance). Newer liver research suggests 2–8 grams per day may be sufficient for liver-enzyme benefits with better tolerability than the older 20-gram protocols. It’s generally best to start with a lower dose to see how you feel, and increase gradually if needed.

It’s also worth pairing betaine with a high-quality natural multivitamin with minerals that includes other methyl donors like folate, vitamin B6, and vitamin B12, since these work together in the same pathway.

Who Benefits the Most From TMG?

People with MTHFR gene variants stand to benefit the most from betaine supplements, since it provides an alternate methylation route. People managing elevated homocysteine, MASLD/MASH, or looking to support exercise recovery may also be good candidates, based on the research above.

You can use SelfDecode to check your genetic traits and get a sense of your optimal diet, supplement, and exercise strategy based on your genes. If you don’t want to test your genes, TMG is still worth trying, though you may not see as dramatic a benefit without knowing your baseline.

Betaine Benefits: Reviews

Since betaine has so much potential to improve health, but clinical research is still catching up, reviews from real users can help you decide whether it’s worth trying.

My Review

TMG’s benefits are real, in my experience. I noticed I felt better within about 20 minutes of taking this supplement — a calming feeling, a focused feeling, and a relaxed feeling. The effects last all day, which I love, so I take it first thing in the morning. After two weeks, my workouts started feeling more effortless too. I only need 750 mg a day and currently use the Source Naturals brand.

Reader & Amazon Reviews

“This has increased my energy and focus as well as keeping my mood much more stable without needing to take five other supplements.”

“Much cheaper than taking SAMe and works just as well in my experience.”

“I have only been taking this for a week and I notice a lot more energy, focus at work, and a better mood… I have MS and my energy is down a lot these days which makes me moody. So far this is helping so I would definitely recommend it.”

“These are helping a lot with my homocysteine levels — I take them with my other B vitamins for an MTHFR variant. I’m noticing a huge difference in my health after four weeks.”

“Vital for artery health by preventing and removing dangerous homocysteine, and a ‘poor man’s SAMe.’ For those spending a small fortune on SAMe for depression, use this instead.”

“I found after a few weeks that my muscle recovery and growth clearly improved, along with heightened focus and increased memory.”

“I started this to help my histamine intolerance. It helps metabolize homocysteine, which aggravates the histamine problem. After just two weeks my intolerance is better.”

“The only downside is every other night I have energy that keeps me up — minor insomnia — but the good side effects (a calming sensation, since I’m an extremely nervous person) have made it worth it.”

“After doing a lot of research about MTHFR polymorphisms, I was surprised to find that official nutrition guidelines largely ignore the BHMT enzyme homocysteine-methionine pathway, which needs TMG and zinc.”

FAQs

If I eat foods containing betaine, do I need a betaine supplement?

TMG is found in many foods, including wheat bran, spinach, seafood, beets, rye, turkey, veal, and beef. However, most cooking methods reduce the TMG content of these foods. Some betaine-rich foods (like wheat and rye) are also worth avoiding for people with gut sensitivities. If you’re looking for a therapeutic effect from TMG, supplementing is usually the more reliable route.

Can you combine betaine with medications?

Betaine anhydrous (TMG) is a natural compound already made in the body, and no major medication interactions are known with it. Betaine HCl, in contrast, may interact with stomach acid–reducing medications, since it’s used to boost stomach acid.

Does betaine increase cholesterol levels?

Betaine supplements can raise LDL cholesterol at higher doses (around 3+ grams a day), by roughly 10% in research. Newer 2025–2026 liver research using 2–4 g/day doses actually found HDL increased with no change in LDL, which is reassuring — but if you have a family history of high cholesterol, it’s worth discussing higher betaine doses with your practitioner first.

When should you take betaine anhydrous?

It’s generally best to take betaine on an empty stomach, though you can take it with food to reduce the risk of GI side effects. Since some people notice mild insomnia, taking it in the morning is usually the better choice.

Is MASLD the same thing as NAFLD, and does betaine still help?

Yes — MASLD (metabolic dysfunction–associated steatotic liver disease) is the new name for what was previously called NAFLD, following a 2023 international nomenclature change intended to reduce stigma and better reflect the underlying metabolic cause. It’s the same condition with the same severity staging, just a more precise name. The betaine research discussed above used the updated MASLD diagnostic criteria and still found meaningful benefit.

What’s the newest research on betaine dosing for liver health?

Pilot trials published in Hepatology in 2025–2026 found that 8 g, 4 g, and 2 g per day of betaine (taken for 12–24 weeks) significantly reduced ALT, AST, and other liver-injury markers in adults with MASLD and elevated ALT, with far fewer GI side effects than the older 20 g/day protocol. A 1 g/day dose did not show a significant benefit, suggesting there’s a minimum effective dose somewhere between 1 and 2 grams daily.

Heidi Moretti, MS, RD, CLT

Heidi Moretti, MS, RD, CLT is The Healthy RD. A registered dietitian for 25 years and author of the bestselling books Cortisol Fix, Period Fix, Gut Fix, and The Whole Body Guide to Gut Health, Heidi has a passion for functional nutrition and natural medicine. She has researched supplements and natural medicine throughout her career, with a focus on helping people gain function and vitality by tackling the root causes of illness.

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