Trimethylglycine (TMG) — also sold as betaine or betaine anhydrous — has become one of the most searched-for methylation supplements in Britain, largely because it pairs so well with NMN and other longevity compounds. You can go straight to Welzo Ultra Purity TMG, browse the wider anti-ageing and longevity range, or see the NMN supplements collection if you are building the pair together. For where TMG fits among the alternatives, start with our pillar guide to longevity supplements and our NMN benefits, side effects and dosage guide. If you are trying to work out where to buy TMG in the UK, which brand is worth your money, and how much to take, this guide walks you through everything: what TMG actually does, the evidence behind it, the safest way to use it, and exactly where to buy a third-party-tested product that ships from a UK warehouse.
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TMG is a small, naturally occurring compound: it is the amino acid glycine carrying three methyl groups — hence tri-methyl-glycine. Your body makes some of it from choline, and you also get it from foods such as beetroot, spinach, quinoa, wheat bran and shellfish. Its headline job is acting as a methyl donor in what biochemists call one-carbon metabolism — the cellular process that keeps DNA, neurotransmitters and detoxification pathways running.
Yes. TMG, betaine and betaine anhydrous all refer to the same molecule. The one thing to watch for is betaine HCl, which is a completely different product used as a digestive aid to support stomach acid — not a methylation supplement. When you are shopping to buy TMG in the UK, make sure the label says trimethylglycine or betaine anhydrous, not betaine HCl.
TMG donates one of its methyl groups to homocysteine, converting it back into methionine via an enzyme called BHMT (betaine-homocysteine methyltransferase). This matters for two reasons. First, it helps keep homocysteine — an amino acid linked to cardiovascular risk when elevated — within a healthy range. Second, it runs in parallel to the folate and vitamin B12 pathway, which is why TMG is popular with people who have an MTHFR gene variation that can slow the folate route. If you want the deeper biochemistry, our NAD+ supplement guide explains how these cycles interact with cellular energy.
Search interest in TMG has climbed alongside the wider longevity movement. Here is what the evidence actually supports — and where it is more modest than the marketing suggests.
This is TMG's best-evidenced use. In healthy adults, betaine at around 6 g/day has been shown to lower fasting plasma homocysteine by roughly 10–15%, and to blunt the post-methionine-load spike by up to 40% (Olthof et al., Journal of Nutrition). A single oral dose can lower homocysteine within about two hours, and the effect is dose-dependent. Broader reviews put the reduction at roughly 5–20% at doses of 4–6 g/day. Importantly, homocysteine is a risk marker; lowering it has not been proven to change heart-attack rates in the general population, so TMG should be seen as supporting a marker, not treating heart disease.
This is the number-one reason UK longevity shoppers buy TMG. When you supplement with NMN to raise NAD+ levels, some of that NAD+ is broken down and cleared through methylation — a process that consumes methyl groups. The theory is that adding TMG replenishes those methyl donors so your overall methylation balance is not depleted. It is a sensible, precautionary pairing rather than a proven necessity, and we cover the nuance in do I need TMG with NMN? and the popular NMN + TMG + resveratrol stack.
Popular pairing: Many people simplify this by buying a combined product such as the Welzo NMN & TMG Ultra Purity Stack, or by adding TMG to an existing NMN routine like NMN Pro 1000.
As a methyl donor and osmolyte, TMG plays a role in liver fat metabolism, which is why it has been researched in the context of fatty-liver support. Evidence in this area is still developing and mostly clinical rather than consumer-focused, so treat liver claims cautiously and speak to a doctor if you have a diagnosed liver condition.
Sports scientists have studied betaine (the same molecule) for years. A 2024 systematic review and meta-analysis of 17 trials in 317 participants found a significant improvement in maximal strength — particularly lower-body strength — and in vertical-jump performance, though it found no clear benefit for upper-body strength, cycling power or muscular endurance (PubMed). Performance studies typically use around 2.5 g/day. If strength and recovery are your goal, TMG may be a modest add-on rather than a headline supplement — see our take on creatine for longevity for a better-evidenced option, and supplements for endurance athletes.
TMG is legal to buy as a food supplement in the UK and is stocked by supplement specialists, longevity brands and general marketplaces. The main decision is not availability — it is quality assurance. Here is how the main options compare.
Welzo is a UK-based health and pharmacy marketplace that dispatches from a UK warehouse, with free shipping on orders over £50 and same-day dispatch on orders placed before 2pm. For most people, buying direct is the simplest route to a traceable, third-party-tested product. The core options are:
You can browse everything in one place via the Welzo TMG collection, and if you are building a wider routine, the NMN supplements range pairs naturally with it.
High-street pharmacies focus on mainstream vitamins, so dedicated TMG is often not reliably stocked in-store — availability comes and goes and tends to favour lower doses. If you have historically checked the high street for NMN and related compounds, our guides to NMN at Holland & Barrett and NMN at Boots explain the same pattern: specialist longevity retailers usually offer better dosing, purity documentation and value.
Marketplaces list dozens of TMG brands, and you can find Welzo's own Ultra Purity TMG there too. The trade-off is quality control: with grey-market listings it can be harder to verify third-party testing, batch traceability and storage conditions. If you buy this way, stick to brands that publish testing and read our guidance on buying supplements on Amazon UK before you check out.
Several UK longevity brands sell good TMG, including options reviewed in our Longevity Box review. Comparing specialists on price-per-gram and testing transparency is worth the few minutes it takes — see our roundups of the cheapest NMN in the UK and how to build a cheaper longevity stack for the same value-first approach applied to TMG.
Because TMG is sold as a food supplement rather than a medicine, quality varies widely between brands. These are the five things worth checking before you buy.
The single most important marker of quality is independent testing. A reputable TMG product is tested by an external lab for purity and to screen for heavy metals and contaminants, with results available as a Certificate of Analysis (CoA). Our explainer on third-party-tested supplements covers exactly what to look for.
Good TMG needs very few — ideally zero — added ingredients. Look for "betaine anhydrous" as essentially the only active, and be wary of long ingredient lists. Our guide to common supplement fillers explains which additives are harmless and which are worth avoiding.
Capsules are convenient and pre-dosed, which suits most people taking TMG for methylation support. Powder is cheaper per gram and lets you scale up to the higher doses used in homocysteine research — but it has a slightly sweet-salty taste and requires accurate measuring. If you are stacking multiple compounds, our minimal supplement stack guide helps you keep pill counts manageable.
UK products range from about 500 mg to 1,000 mg per serving. There is no single "correct" strength — it depends on your goal (see the dosage section below) — but a clearly stated milligram amount per capsule is non-negotiable.
| Format | Typical strength | Best for | Notes |
|---|---|---|---|
| High-strength capsules | 1,000 mg | NMN stackers, one-a-day convenience | Look for third-party testing and no fillers |
| Standard capsules | 500–750 mg | Gentle daily start, flexible titration | Easy to build up gradually |
| Powder | Weigh your own | Higher homocysteine-support doses; best price per gram | Needs an accurate scale; mild taste |
| Combined NMN + TMG | NMN plus ~500–1,000 mg TMG | Simplest longevity routine | One purchase covers methyl-donor cover |
TMG dosing depends entirely on why you are taking it. The ranges below reflect the research literature, but your personal dose should be discussed with your GP or pharmacist, particularly if you take other medication.
Many people start at 500 mg–1 g/day and stay there. Research showing meaningful reductions in homocysteine tends to use higher doses — commonly 4–6 g/day — but those higher amounts are also where the cholesterol caution below applies. Reviews suggest keeping to 4 g/day or less captures much of the homocysteine benefit without the unwanted effect on blood lipids.
For methyl-donor "cover" alongside NMN, most people use a modest 500 mg–1 g of TMG per day — you are topping up methyl groups, not treating high homocysteine. Timing-wise, TMG is usually taken in the morning with NMN; our guides on when to take NMN and taking NMN with food apply equally to TMG.
Sports studies most often use around 2.5 g/day of betaine, taken consistently over several weeks. Benefits, where they occur, are modest and mostly relate to lower-body strength.
Practical tip: Start at the low end and build up only if needed. For most people using TMG to support an NMN routine, around a gram a day is plenty. There is little reason to push into the multi-gram range unless you are specifically targeting a raised homocysteine reading under a doctor's supervision — and at those higher doses, keeping an eye on your cholesterol makes sense.
TMG has a reasonable margin of safety and is well tolerated by most people at supplement doses. Like any active compound, it has caveats.
At higher doses, some people notice mild digestive upset (nausea, bloating or loose stools) and, occasionally, a fishy body odour caused by a build-up of trimethylamine. These effects are dose-related and usually resolve by lowering the amount.
This is the most important nuance. Randomised, placebo-controlled research found that betaine supplementation — particularly at doses of 6 g/day or more — can raise LDL ("bad") cholesterol and triglycerides in healthy people, an effect visible within about two weeks (Olthof et al., NCBI). This is precisely why most experts recommend keeping general-use doses at or below 4 g/day, and why folic acid and vitamin B12 remain first-line for clinically raised homocysteine. If you have high cholesterol or cardiovascular disease, discuss TMG with your GP first.
Speak to a healthcare professional before buying TMG if you are pregnant or breastfeeding, take prescription medication, have high cholesterol, kidney disease or a diagnosed cardiovascular or liver condition. If you are new to supplements generally, our primers on how to start longevity supplements and whether you can take supplements together are a good place to begin.
TMG can be taken with or without food, though many people take it in the morning to fit around an NMN routine. Consistency matters more than timing — the homocysteine-lowering effect builds with regular daily use. Keep it in a cool, dry place away from light, and don't exceed the dose on the label. If you are combining several compounds, a written schedule helps; our supplement timing chart and guide to building a complete longevity stack make this straightforward.
TMG is one of several methylation supports, and they are not interchangeable. Here is how it compares to the alternatives you will see mentioned online.
| Compound | Role in methylation | When it's chosen |
|---|---|---|
| TMG (betaine) | Direct methyl donor via the BHMT pathway | Cost-effective, well-tolerated all-rounder; popular with NMN |
| Methylfolate | Feeds the folate/methionine-synthase pathway | Often preferred with certain MTHFR variants — compare in our TMG vs methylfolate guide |
| SAMe | The universal methyl donor itself | Used more for mood and joint support; pricier |
| Choline | Precursor the body converts into TMG | Broader role in liver and brain health |
For the bigger picture on how methylation fits into ageing biology, see our explainer on the hallmarks of ageing and our overview of the best longevity supplements.
For a third-party-tested product that ships fast from a UK warehouse, buying direct from a UK retailer such as Welzo is the most reliable route. Options include Ultra Purity TMG 1000 mg, Swanson TMG 500 mg and Life Extension TMG powder, all in the TMG collection.
Yes — TMG, betaine and betaine anhydrous are the same molecule. Just avoid confusing it with betaine HCl, which is a digestive supplement, not a methyl donor.
Dedicated TMG is not reliably stocked on the high street, and where it appears it tends to be lower-dose. Specialist and online longevity retailers usually offer better strengths, purity documentation and value.
It's a common precaution rather than a strict requirement. NMN metabolism consumes methyl groups, and TMG replenishes them. Whether you personally need it depends on your wider diet and routine — read do I need TMG with NMN? for the full picture.
For methyl-donor support alongside NMN, most people take 500 mg–1 g/day. Homocysteine research uses higher doses (up to 4–6 g/day), but staying at or below 4 g/day helps avoid effects on cholesterol. Start low and build up under professional guidance.
TMG can be taken any time, with or without food. Many people take it in the morning to align with NMN. Daily consistency matters more than the exact time.
At sensible doses it is well tolerated. Higher doses can cause mild digestive upset, a fishy body odour, and — at 6 g/day or more — increases in LDL cholesterol and triglycerides. Lowering the dose usually resolves these.
TMG has been used safely in research and as a food supplement for years. For long-term daily use, keeping to moderate doses and reviewing your routine periodically with a healthcare professional is sensible, especially if you have any cardiovascular risk factors.
TMG is commonly stacked with NMN, resveratrol and B-vitamins. It generally combines well, but check for overlaps and interactions — our guide on taking supplements together explains how.
Capsules are convenient and pre-dosed; powder is cheaper per gram and lets you fine-tune higher doses. Choose based on your goal and how precise you want to be.
Medical disclaimer: This article is for general information and education only and is not a substitute for professional medical advice, diagnosis or treatment. TMG is a food supplement and is not intended to diagnose, treat, cure or prevent any disease. Always read the product label and consult your GP, pharmacist or a qualified healthcare professional before starting any new supplement — particularly if you take prescription medication, have high cholesterol or a cardiovascular, kidney or liver condition, or are pregnant or breastfeeding. Reviewed by Dr Zeeshan Afzal (MBBS, FCPS, MRCP(UK)), Welzo medical author.
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