TMG vs Methylfolate for Methylation Support

Medically reviewed by Dr Zeeshan Afzal (MBBS), Medical Officer at Welzo.
Written by the Welzo Longevity Editorial Team · Last updated: 23 July 2026 · Reading time: approximately 13 minutes
This article is for general information and is not a substitute for individual medical advice. Speak to your GP or pharmacist before starting any supplement, particularly if you are pregnant, taking prescription medication or managing a diagnosed condition.

TMG and methylfolate are both sold as "methylation support", but they are not interchangeable. TMG (trimethylglycine, also called betaine) donates a methyl group directly, through an enzyme found mainly in the liver and kidneys. Methylfolate (5-MTHF) feeds the folate and vitamin B12 route that operates in essentially every cell in the body.

For the wider picture, see our pillar guide to longevity supplements and our detailed guide to NMN benefits, side effects and dosage. If TMG is the route you settle on, it is available as Welzo Ultra Purity TMG, alongside the full NMN supplement and anti-ageing and longevity ranges.

The two compounds lower homocysteine through different doors — which is precisely why the choice between them depends on your diet, your genetics, your bloodwork and what else is in your stack. If you have arrived here because you are taking an NAD+ precursor and read that it "burns through methyl groups", the short version is below, and the mechanism is explained in full further down.

TMG vs methylfolate at a glance

Before the biochemistry, here is the practical comparison most people are searching for.

What methylation actually does in the body

Methylation is the transfer of a one-carbon unit — a methyl group, written CH₃ — from one molecule to another. It sounds trivial. It is not. Methyl transfer switches genes on and off, builds and breaks down neurotransmitters such as dopamine, serotonin and adrenaline, produces creatine and phosphatidylcholine, packages up toxins for excretion, and maintains the DNA methylation patterns that are used to estimate biological age. Loss of stable epigenetic patterning is one of the recognised hallmarks of ageing, which is why methylation has become such a preoccupation in longevity circles.

The methionine–homocysteine cycle in plain English

Almost every methylation reaction in the body uses the same universal donor: S-adenosylmethionine, or SAM. Once SAM hands over its methyl group it becomes S-adenosylhomocysteine (SAH), which is then broken down to homocysteine. Homocysteine sits at a crossroads with three possible fates:

1. Remethylation via folate and B12 — methionine synthase takes a methyl group from 5-methyltetrahydrofolate (methylfolate) and, using vitamin B12 as a cofactor, converts homocysteine back to methionine. This route runs in virtually every cell.
2. Remethylation via betaine — BHMT takes a methyl group directly from TMG and converts homocysteine back to methionine, producing dimethylglycine (DMG) as a by-product. This route is concentrated in the liver and kidneys.
3. Transsulfuration — homocysteine is committed irreversibly to cysteine and ultimately glutathione, via cystathionine beta-synthase, which requires vitamin B6.

Under normal physiological conditions the two remethylation routes are thought to contribute broadly equally to homocysteine removal in humans.^[11] That single fact is the whole argument of this article: they are parallel systems with partial redundancy, so which one you should support depends on which one is under strain.

Why homocysteine is the marker everyone talks about

Homocysteine is used as a convenient, cheap readout of methylation status, and raised levels are consistently associated with cardiovascular and cognitive risk in observational data. It is important to be honest about what the intervention trials show, though. A meta-analysis of 19 randomised controlled trials including 47,921 participants found that B-vitamin supplementation did not reduce the risk of cardiovascular disease, myocardial infarction, coronary heart disease or cardiovascular death, although it did reduce stroke risk by around 12%.^[7]

In other words: lowering homocysteine is a reasonable goal for metabolic housekeeping, but no supplement should be sold to you as heart-attack insurance. This nuance matters, and it is the same evidence-first lens we apply in our guide to longevity supplements that don't work.

What is TMG (trimethylglycine)?

TMG is glycine with three methyl groups attached to its nitrogen. It was first isolated from sugar beet (Beta vulgaris), which is where the alternative name betaine comes from. Chemically it is a zwitterion, and biologically it does two jobs: it acts as an osmolyte that helps cells manage fluid balance, and it acts as a methyl donor.

How TMG works: the BHMT pathway

When homocysteine builds up in liver or kidney tissue, BHMT strips one methyl group from TMG and hands it to homocysteine, regenerating methionine. TMG becomes DMG (dimethylglycine), which can be further demethylated and eventually feeds one-carbon units back into the folate pool. Notably, this reaction requires no vitamin B12 and no folate, which is exactly why TMG is of interest to people whose folate route is compromised.

Food sources of TMG

Most people get somewhere between 100 and 400 mg of betaine daily from food, though intake varies enormously with diet. Wheat and beet products dominate the list.^[12]

What the evidence shows for TMG

The homocysteine data for betaine are unusually clean for a supplement ingredient, because betaine anhydrous is also a licensed medicine (Cystadane) for the rare inherited condition homocystinuria.

• Dose-response in healthy adults. Thirty-four healthy men and women took 1 g, 3 g and 6 g of betaine daily for consecutive one-week periods. Mean plasma total homocysteine fell by 1.1% (not significant), 10.0% and 14.0% respectively. Adding 1 mg of folic acid to the 6 g dose produced a further 5% reduction, confirming that the two pathways are additive rather than duplicative.^[3]
• Post-meal homocysteine spikes. In a six-week randomised trial in people with mildly elevated homocysteine, betaine blunted the rise in homocysteine after a methionine load, an effect folic acid did not reproduce to the same degree.^[4]
• Regulatory position. After reviewing the trial evidence, the European Food Safety Authority concluded the claim was substantiated, and the EU authorised "betaine contributes to normal homocysteine metabolism" for foods providing at least 500 mg per portion, with the beneficial effect obtained at 1.5 g/day.^[1][2]
• Clinical use. In a registry of 125 patients with homocystinuria treated for a mean of 7.4 years, betaine anhydrous produced a mean overall reduction in plasma homocysteine of 29%.^[5]

If you have decided TMG belongs in your routine, our practical UK sourcing guide covers brands, formats and pricing: where to buy TMG in the UK.

What is methylfolate (5-MTHF)?

Folate is vitamin B9. It exists in several forms, and the distinction between them is the source of most of the confusion in this category:

• Food folate — the naturally occurring polyglutamate forms in leafy greens, pulses and liver.
• Folic acid — the synthetic, fully oxidised form used in fortification and most cheap supplements. It is not biologically active until the body reduces it, first to dihydrofolate and then to tetrahydrofolate, via the enzyme dihydrofolate reductase, before it can be methylated.
• Methylfolate (L-5-MTHF, levomefolic acid) — the finished, active form that already circulates in blood and crosses into tissues, including across the blood–brain barrier.

How methylfolate works: the MTHFR step

The enzyme methylenetetrahydrofolate reductase (MTHFR) performs the final conversion of 5,10-methylene-THF into 5-methyl-THF. A common single-nucleotide variant, C677T, produces a thermolabile enzyme; people carrying two copies (the TT genotype) have roughly half the enzyme activity of those with the common CC genotype, and correspondingly higher homocysteine.^[8] Supplementing methylfolate sidesteps the sluggish step entirely, because you are supplying the product of the reaction rather than the substrate.

Methylfolate vs folic acid: what the data actually show

In a randomised crossover study, healthy women received either 400 µg of folic acid or 416 µg of [6S]-5-MTHF. The methylfolate arm produced a significantly higher peak plasma folate and a significantly greater area under the curve, with a faster time to peak — and this held true regardless of MTHFR genotype. Unmetabolised folic acid appeared regularly in plasma after folic acid dosing, but rarely after methylfolate.^[6] A separate pharmacokinetic study in cardiovascular patients homozygous for C677T reached the same conclusion on bioavailability.^[10]

The US Office of Dietary Supplements puts it plainly: supplements containing 5-MTHF may be better than folic acid for some people with the MTHFR C677T variant, because their bodies can use this form more easily.^[7]

Food sources of folate

Dark green leafy vegetables (spinach, kale, spring greens), broccoli, Brussels sprouts, asparagus, lentils, chickpeas, beans, liver, avocado and citrus fruit. Folate is heat-sensitive and water-soluble, so heavy boiling destroys a meaningful proportion of it — steaming or quick sautéing preserves far more. UK adults need 200 µg of folate a day, rising to a recommended 400 µg supplement for anyone pregnant or trying to conceive.^[9]

TMG vs methylfolate: head-to-head

Mechanism: direct donor vs enzymatic carrier

TMG is a stoichiometric methyl donor — it physically carries three methyl groups and gives one away. Methylfolate is a carrier in a catalytic cycle: it delivers a methyl group and is regenerated. Practically, this is why TMG is dosed in grams and methylfolate in micrograms. It also means TMG can be "used up" by a heavy methylation demand in a way that a functioning folate cycle largely cannot.

Coverage: which tissues benefit

This is the most under-appreciated difference. BHMT expression is largely restricted to liver and kidney in humans. Methionine synthase is ubiquitous. If your concern is neurological — mood, cognition, nerve health — the folate and B12 route is the relevant one, and TMG will not substitute for it. If your concern is hepatic — fatty liver, alcohol-related liver stress, or clearing a homocysteine load after a protein-heavy meal — TMG is working exactly where the demand is.

Homocysteine lowering: which is stronger?

At standard supplement doses, folate is the more efficient tool per milligram, and it is the first-line nutrient in every clinical protocol for raised homocysteine. TMG has a bigger effect on post-methionine-load homocysteine — the spike that follows a high-protein meal — because the BHMT route has spare capacity that can be recruited on demand. The two together outperformed either alone in the dose-response trial described above.^[3]

Genetics: does MTHFR change the answer?

If you carry the TT genotype, methylfolate is the more logical first choice, because it bypasses the impaired enzyme. TMG is a reasonable second lever, because BHMT is entirely unaffected by MTHFR status — it provides an alternative door when the main one is stiff. Note, though, that direct-to-consumer genotyping results should be interpreted with a clinician rather than acted on unilaterally; a raised homocysteine result is a far more actionable number than a genotype alone.

Cost per month

Both are among the cheapest ingredients in the longevity category. TMG powder is typically a few pence per gram; methylfolate at 400–800 µg is usually included in any decent B-complex at negligible marginal cost. Neither should be a significant line item — a point we make in detail in our breakdown of why supplements are expensive and our UK longevity stack cost analysis.

Which one should you take?

Choose methylfolate if…

• Your folate intake is genuinely low — few vegetables, restrictive dieting, heavy alcohol use, coeliac or inflammatory bowel disease.
• You carry the MTHFR C677T TT genotype or have taken folic acid without moving your numbers.
• You are pregnant, planning a pregnancy, or of childbearing age — although in this specific situation, follow NHS guidance and take the recommended 400 µg supplement rather than improvising.^[9]
• Your interest is cognitive or mood-related, where the body-wide methionine synthase route matters most.
• You are on a plant-based diet — see our guide to vegan longevity supplements, where B12 is the more urgent gap.

Choose TMG if…

• You take a high daily dose of an NAD+ precursor (explained in the next section).
• Your diet is low in wheat germ, bran, quinoa and beetroot — betaine intake tracks these foods closely.
• Your homocysteine remains raised despite good folate and B12 status.
• You train hard: betaine is a well-established ergogenic aid in the strength and power literature, independent of its methylation role.
• Liver health is a focus, given betaine's role in hepatic fat metabolism.^[13]

When taking both makes sense

For most people building a longevity routine, the answer is both — at modest doses. The dose-response trial showed the combination outperformed either nutrient alone.^[3] A reasonable baseline is a B-complex supplying methylfolate and methylcobalamin, plus 500 mg–1 g of TMG if you are running an NAD+ precursor. If you are assembling a routine from scratch, start with our step-by-step guide on how to start longevity supplements and the broader longevity supplements guide.

The NMN and NAD+ connection: why NMN users are told to take TMG

This is the single most common reason people search for TMG in the first place, so it deserves an honest answer.

Excess nicotinamide in the body is cleared by an enzyme called nicotinamide N-methyltransferase (NNMT). NNMT takes a methyl group from SAM and attaches it to nicotinamide, producing 1-methylnicotinamide and SAH.^[14] Because SAH is the immediate precursor of homocysteine, upregulated NNMT activity consumes methyl groups and generates homocysteine as a by-product. That is the mechanistic basis for the widely repeated advice to pair TMG with NMN or NR.

If you are running this combination, two further resources will help: our breakdown of the NMN, TMG and resveratrol stack, and the wider NAD+ supplement guide. For a high-strength, third-party-tested option, NMN Pro 1000 is the product most Welzo customers pair with TMG, and timing questions are answered in when to take NMN.

Dosage, timing and cofactors

TMG dosage

Methylfolate dosage

For general use, 400–800 µg of L-5-MTHF daily is the standard range, which is also the range found in good B-complex products. UK adults need 200 µg of folate a day in total, and the NHS notes that taking 1 mg or less a day of supplemental folic acid is unlikely to cause harm.^[9] Higher doses of methylfolate — the multi-milligram range used adjunctively in some psychiatric protocols — should only be taken under medical supervision.

The cofactors that make either one work

• Vitamin B12 (methylcobalamin or hydroxocobalamin) — non-negotiable if you are taking methylfolate. Without B12, methionine synthase stalls and folate becomes trapped in its methyl form.
• Vitamin B6 (P5P) — drives the transsulfuration exit, which is how homocysteine actually leaves the cycle rather than being endlessly recycled.
• Riboflavin (B2) — a cofactor for the MTHFR enzyme itself, and often the missing piece in people with C677T variants.
• Glycine — buffers surplus methyl groups. Useful if you find methyl donors over-stimulating.

Timing

TMG is water-soluble and can be taken with or without food, though taking it with a meal reduces the mild GI upset some people notice. Many users take it in the morning with their NAD+ precursor. Methylfolate is best taken in the morning too, as a minority of people find it activating close to bedtime. Our supplement timing chart maps out a full daily schedule, and if you are wondering what can safely share a dose, see can you take supplements together and which supplements to take on an empty stomach.

Side effects, safety and who should avoid them

TMG side effects

• Cholesterol. The clearest signal. Doses of 6 g/day raised total and LDL cholesterol in several trials, and a 4 g/day dose raised total and LDL cholesterol in overweight participants with metabolic syndrome, though not in normal-weight subjects.^[15][2] This is why the EU mandates a warning above 4 g/day and why we do not recommend gram-loading TMG casually.
• Gastrointestinal. Nausea, bloating, cramps and diarrhoea, mostly at higher doses.
• Body odour. A small number of people report a fishy odour at high intakes, related to downstream trimethylamine metabolism.
• Raised methionine. The most common side effect in the medical setting. Very rarely, excessive methionine elevation has been linked to cerebral oedema in patients treated for homocystinuria — an extremely uncommon event at clinical doses, but the reason self-prescribing multi-gram doses is unwise.^[13]

Methylfolate side effects

• Masking B12 deficiency. The core safety concern with any folate supplement. Folate can correct the anaemia caused by B12 deficiency while the neurological damage continues unchecked, potentially becoming irreversible.^[7] Always take B12 alongside, and get B12 checked if you are over 60, vegan, on metformin or a long-term proton pump inhibitor.
• "Overmethylation" symptoms. Anxiety, irritability, insomnia or headache within a day or two of starting, most often reported at higher doses. It resolves on stopping or reducing the dose. The mechanism is debated; the practical response is to start low.
• Upper limit. The tolerable upper intake level for supplemental folic acid is 1,000 µg/day for adults.^[7]
• Cancer signal. High folic acid intakes have been linked to progression of pre-existing colorectal lesions in some analyses; anyone with a history of colorectal adenomas should discuss folate supplementation with their doctor.^[7]

Who should speak to a doctor first

Anyone who is pregnant or breastfeeding; anyone with an undiagnosed anaemia; anyone with a history of colorectal cancer or adenomas; anyone taking methotrexate, sulfasalazine, phenytoin or other anti-epileptics (all of which interact with folate); anyone on lipid-lowering therapy considering multi-gram TMG; anyone with kidney disease; and anyone with a diagnosed inborn error of metabolism, who should follow their specialist's protocol rather than any general guidance.

How to test and track your response

Guesswork is expensive. Three inexpensive blood markers turn this from a hunch into a measurable intervention:

1. Plasma total homocysteine — the primary readout. Fasting sample, ideally repeated 8–12 weeks after any change.
2. Serum or active vitamin B12 — essential before starting any folate supplement.
3. Serum or red cell folate — red cell folate reflects longer-term status and is the more useful of the two if available.

If you are tracking longevity interventions more broadly, epigenetic clocks and other markers are covered in our guides to biological age testing and how to lower your biological age. And if you are wondering how patient to be, how long supplements take to work sets realistic expectations — for homocysteine, betaine's effect is measurable within days to weeks, but a repeat blood test at 8–12 weeks is the sensible checkpoint.

How to choose a quality TMG or methylfolate product in the UK

• Form matters for folate. Look for L-5-MTHF (often as the calcium or glucosamine salt) rather than plain folic acid. The "L" or "6S" prefix indicates the biologically active isomer.
• Form matters less for TMG. Betaine anhydrous is betaine anhydrous. Do not confuse it with betaine HCl, a different product marketed for stomach acid.
• Check for third-party testing. Purity and identity testing is the single best quality signal in this industry — see third-party tested supplements and how to read a supplement certificate of analysis.
• Watch the excipient list. Our guide to supplement fillers explains which are inert and which are worth avoiding.
• Do not overpay. Both ingredients are commodity-priced. If a product costs more than a few pounds a month per active ingredient, you are paying for branding.

The verdict

The framing of "TMG vs methylfolate" is slightly misleading, because the biochemistry shows they are teammates rather than rivals: the trial that tested them together found a greater homocysteine reduction from the combination than from either alone.^[3]

If forced to pick one, methylfolate wins on breadth: folate is an essential vitamin, it works in every cell including the brain, deficiency is genuinely common, and the MTHFR argument for the methylated form is well supported. TMG is the specialist tool — outstanding value, real evidence behind its homocysteine effect at 1.5 g, and the logical companion to a high-dose NAD+ precursor, but with a genuine ceiling above which cholesterol becomes a concern.

The pragmatic protocol for most healthy adults: get folate and B12 right first, add 500 mg–1 g of TMG if you are taking an NAD+ precursor or your diet is low in betaine-rich foods, test homocysteine before and after, and keep TMG below 2 g/day unless a clinician has told you otherwise. To see where these fit within a complete routine, our longevity stack article maps the whole thing out, and the minimal supplement stack shows what to keep if you want to cut everything else.

Frequently asked questions

References

1. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to betaine and contribution to normal homocysteine metabolism (ID 4325). EFSA Journal 2011;9(4):2052. https://www.efsa.europa.eu/en/efsajournal/pub/2052
2. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods — consolidated text (betaine entry, conditions of use). EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02012R0432-20170822
3. Schwab U, Törrönen A, Meririnne E, et al. The effect of low doses of betaine on plasma homocysteine in healthy volunteers. British Journal of Nutrition 2004. PMID 15522136. https://pubmed.ncbi.nlm.nih.gov/15522136/
4. Steenge GR, Verhoef P, Katan MB. Betaine supplementation lowers plasma homocysteine in healthy men and women. Journal of Nutrition 2003;133(5):1291–1295. PMID 12730412. https://pubmed.ncbi.nlm.nih.gov/12730412/
5. Valayannopoulos V, Schiff M, Guffon N, et al. Betaine anhydrous in homocystinuria: results from the RoCH registry. Orphanet Journal of Rare Diseases 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6419445/
6. Prinz-Langenohl R, Brämswig S, Tobolski O, et al. [6S]-5-methyltetrahydrofolate increases plasma folate more effectively than folic acid in women with the homozygous or wild-type 677C→T polymorphism of methylenetetrahydrofolate reductase. British Journal of Pharmacology 2009. PMID 19917061. https://pubmed.ncbi.nlm.nih.gov/19917061/
7. National Institutes of Health, Office of Dietary Supplements. Folate — Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
8. Huo Y, Qin X, Wang J, et al. MTHFR C677T and MTR A2756G polymorphisms and the homocysteine lowering efficacy of different doses of folic acid in hypertensive Chinese adults. Nutrition Journal 2012. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3274435/
9. NHS. Vitamins and minerals — B vitamins and folic acid. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/
10. Willems FF, Boers GH, Blom HJ, et al. Pharmacokinetic study on the utilisation of 5-methyltetrahydrofolate and folic acid in patients with coronary artery disease. PMID 14769778. https://pubmed.ncbi.nlm.nih.gov/14769778/
11. Finkelstein JD. The metabolism of homocysteine: pathways and regulation. European Journal of Pediatrics 1998;157(Suppl 2):S40–S44. PMID 9587024. https://pubmed.ncbi.nlm.nih.gov/9587024/
12. Zeisel SH, Mar MH, Howe JC, Holden JM. Concentrations of choline-containing compounds and betaine in common foods. Journal of Nutrition 2003;133(5):1302–1307. PMID 12730414. https://pubmed.ncbi.nlm.nih.gov/12730414/
13. Arumugam MK, Paal MC, Donohue TM, et al. Beneficial effects of betaine: a comprehensive review. Biology 2021;10(6):456. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8224793/
14. Li X, et al. Nicotinamide N-methyltransferase (NNMT): a novel therapeutic target for metabolic syndrome. Frontiers in Pharmacology 2024. https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1410479/full
15. Olthof MR, van Vliet T, Verhoef P, Zock PL, Katan MB. Effect of homocysteine-lowering nutrients on blood lipids: results from four randomised, placebo-controlled studies in healthy humans. PLoS Medicine 2005;2(5):e135. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1140947/
16. EFSA Panel on Nutrition, Novel Foods and Food Allergens. Safety of betaine as a novel food pursuant to Regulation (EC) No 258/97. EFSA Journal 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7009864/
17. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury — Betaine. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.ncbi.nlm.nih.gov/books/NBK548774/
18. National Institutes of Health, Office of Dietary Supplements. Vitamin B12 — Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

About the reviewer. Dr Zeeshan Afzal (MBBS) is a practising medical doctor and Medical Officer at Welzo, where he reviews clinical and nutritional content for accuracy against current published evidence and UK regulatory guidance.

Editorial policy. Welzo articles cite primary sources — peer-reviewed research, regulatory opinions and national health bodies — in preference to secondary reporting. Claims about supplement effects are limited to what the cited evidence supports. This article is reviewed and updated at least annually.