Why does betaine cause a fishy smell?

Betaine is metabolised in part to trimethylamine (TMA), a compound that produces a fish-like odour. In most people, TMA is rapidly oxidised by the liver enzyme FMO3 into an odourless form. However, individuals with a genetic variation that reduces FMO3 activity metabolise TMA more slowly, leading to noticeable body odour or fishy breath. Reducing the dose or splitting it across two smaller servings may help.

Is betaine the same as beetroot extract?

Not exactly. Beetroot extract is a whole-food supplement containing multiple active compounds including dietary nitrates and betaine. Betaine Anhydrous is the isolated trimethylglycine compound. Beetroot extract is primarily used for its nitrate content and NO-boosting effects; betaine anhydrous is used for its methylation, osmolytic, and strength benefits. They are complementary rather than interchangeable.

Does betaine anhydrous need to be taken on rest days?

Yes — consistent daily intake is important because betaine works through chronic physiological adaptation rather than an acute pre-workout effect. Like creatine, its benefits depend on maintaining elevated tissue levels over time. A simple approach is to take your daily 2.5g dose at the same time each day regardless of whether you train.

Can betaine anhydrous help with fat loss?

There is some evidence that betaine can support favourable body composition changes — studies have found reductions in fat mass alongside increases in lean mass with 2.5g per day over six weeks. Betaine is not a fat burner in the conventional stimulant sense — any fat loss effect is modest and should be viewed as a secondary benefit alongside its primary performance applications.

Is betaine anhydrous the same as TMG?

Yes — betaine anhydrous and trimethylglycine (TMG) are the same compound. Betaine is the common name used in the supplement industry; TMG is the more chemically precise name. The anhydrous designation means it is in a dehydrated, water-free form — the standard supplement formulation. If you see either name on a label, they refer to the same ingredient.

How does betaine compare to creatine for performance?

Creatine has a larger and more consistent body of evidence and is generally considered the stronger of the two for strength and power. Betaine's evidence base is growing but smaller, with typically more modest effect sizes. That said, their mechanisms are complementary — betaine's contributions to methylation, homocysteine reduction, and osmolytic hydration offer benefits creatine does not. For most athletes, the optimal approach is to use both together rather than choosing between them.

What is Betaine Anhydrous?

Betaine Anhydrous, also known as trimethylglycine (TMG), is a naturally occurring compound derived from the amino acid glycine. It is found in foods such as beetroot, spinach, quinoa, and whole grains, and plays several important roles in human physiology — most notably as a methyl donor in a process called methylation, which underpins protein synthesis, liver function, and cardiovascular health.

In the context of sports nutrition, betaine has gained significant traction over the past decade as research has demonstrated its ability to enhance muscle strength, power output, and body composition. It works through two primary mechanisms: supporting cellular hydration by acting as an osmolyte — drawing water into muscle cells to maintain optimal fluid balance — and contributing to the synthesis of creatine within the body through its role in the methylation cycle (Healthline).

Unlike some pre-workout ingredients that produce acute, session-by-session effects, betaine’s performance benefits build over time with consistent daily supplementation — making it more analogous to creatine than to caffeine or citrulline in terms of how and why it works.

Benefits of Betaine Anhydrous in Fitness

Enhances Muscle Strength and Power Output

Several well-controlled studies have demonstrated that betaine supplementation improves maximal strength, peak power, and force production in resistance-trained individuals. The proposed mechanisms include its role in creatine biosynthesis — supporting the body’s own phosphocreatine system — as well as its osmolytic function, which maintains muscle cell volume and hydration under exercise stress. Meta-analyses have confirmed a meaningful benefit to strength performance with consistent use over several weeks (NCBI).

Supports Muscle Growth and Favourable Body Composition

Research has linked betaine supplementation to improvements in lean muscle mass and reductions in body fat percentage when combined with structured resistance training. One frequently cited six-week study found participants supplementing with 2.5g of betaine daily gained significantly more lean mass and lost more fat than the placebo group, suggesting effects on both anabolic signalling and fat metabolism. These body composition benefits appear to require at least four to six weeks of consistent use to manifest (NCBI).

Improves Endurance and Work Capacity

Beyond maximal strength, betaine has been shown to improve muscular endurance and total work capacity during resistance training — specifically the ability to maintain performance across multiple sets and higher rep ranges. This is thought to relate to its osmolytic role in protecting muscle cells from exercise-induced dehydration and its contribution to reduced fatigue accumulation over the course of a session (NCBI).

Supports Methylation and Cardiovascular Health

As a methyl donor, betaine plays an important role in converting homocysteine — an amino acid associated with cardiovascular risk when elevated — into methionine. Elevated homocysteine is linked to increased risk of heart disease and impaired recovery, and betaine supplementation has been shown to meaningfully reduce plasma homocysteine levels. This makes it a supplement with relevance beyond pure performance, particularly for athletes with higher protein intakes who may be at greater risk of elevated homocysteine (NCBI).

Aids Liver Function

Betaine is used clinically to support liver health, particularly in the context of non-alcoholic fatty liver disease (NAFLD). Its role in methylation supports hepatic fat metabolism and protects liver cells from oxidative stress. For athletes supplementing with high-protein diets and multiple compounds, betaine’s liver-supportive properties add a secondary health benefit beyond performance (Mayo Clinic).

Dosage and Supplementation

The research on betaine is unusually consistent on dosing — the majority of studies demonstrating performance benefits use 2.5g per day, typically split across two doses:

Goal	Recommended Dose	Notes
Strength and power	2.5g per day	Split into 2 x 1.25g doses; take consistently daily
Body composition	2.5g per day	Minimum 4–6 weeks for measurable effects
Homocysteine reduction	1.5–3g per day	Can be taken with meals; does not need to be pre-workout
Liver support (clinical)	1–2g per day	Typically under medical supervision at therapeutic doses

Like creatine and beta-alanine, betaine’s benefits are cumulative rather than acute. Taking it consistently every day — including rest days — is more important than precise timing around training. That said, it is commonly included in pre-workout formulas and taken pre-session for convenience. Consuming it with food reduces the small risk of gastrointestinal discomfort at higher doses (NCBI).

Side Effects and Safety

Betaine Anhydrous is generally well-tolerated at recommended doses, with a safety profile comparable to other widely used sports supplements. Potential side effects include:

Body odour — the most distinctive and frequently reported side effect. In some individuals, betaine supplementation causes a mild fishy body odour due to the production of trimethylamine during metabolism. This is more common at higher doses and in individuals with a reduced ability to metabolise trimethylamine (a genetic variation affecting the FMO3 enzyme) (NCBI).
Gastrointestinal discomfort — nausea, bloating, or diarrhoea can occur at doses above 4g, particularly on an empty stomach. Splitting the daily dose and taking with food typically resolves this (WebMD).
Elevated LDL cholesterol — some research has found that betaine supplementation may modestly raise LDL cholesterol levels in certain individuals. Those with pre-existing lipid concerns should monitor this and consult a doctor if needed.

Individuals with kidney disease, cardiovascular conditions, or elevated cholesterol should seek medical advice before supplementing. For healthy adults, betaine at 2.5g per day is considered safe for ongoing use (Mount Sinai).

Dietary Sources of Betaine

Betaine is found naturally in a range of foods, with some of the highest concentrations in:

Beetroot — one of the richest dietary sources, which is also where betaine gets its name (from the genus Beta vulgaris).
Spinach — a significant plant-based source, contributing meaningful betaine alongside other micronutrients.
Quinoa — one of the better grain-based sources, relevant for those following plant-based diets.
Wheat bran and wheat germ — among the highest concentrations found in any food, though not always consumed in large quantities.
Shellfish — shrimp and other shellfish contain notable betaine levels relative to their serving size.

While a varied diet contributes to baseline betaine intake, dietary amounts alone are unlikely to reach the 2.5g per day associated with performance benefits in research. Supplementation remains the most practical route to achieving effective doses consistently.

Combining Betaine Anhydrous with Other Supplements

Creatine Monohydrate — a highly complementary pairing. Betaine contributes to the body’s own creatine synthesis through methylation, while supplemental creatine directly saturates muscle phosphocreatine stores. Together they support both the internal production and external supply of creatine, making this one of the most logical combinations for strength and power athletes.

Citrulline — betaine’s cellular hydration and volumisation effects pair well with citrulline’s blood flow and pump benefits. Some research suggests betaine may enhance the overall pump experience alongside NO-boosting ingredients by maintaining intramuscular fluid balance.

Beta-Alanine — both betaine and beta-alanine work through chronic accumulation rather than acute effects, making them natural co-ingredients in pre-workouts designed to be taken consistently over time. Their mechanisms are entirely distinct — betaine supports osmolytic balance and methylation; beta-alanine buffers acid — and they do not interfere with each other.

Protein Supplements — adequate protein intake amplifies betaine’s body composition effects by providing the amino acids needed for the lean mass gains that betaine’s anabolic signalling supports. The two work synergistically for muscle-building outcomes over a training block.

FAQs about Betaine Anhydrous

Betaine’s performance benefits are cumulative, not acute. Most research demonstrating meaningful improvements in strength, power, and body composition uses supplementation periods of four to six weeks at 2.5g per day. Unlike caffeine or citrulline — which produce noticeable effects within the same session — betaine works by gradually supporting methylation, cellular hydration, and creatine synthesis over time. Consistent daily use is essential; taking it only on training days will slow the process.

Betaine is metabolised in part to trimethylamine (TMA), a compound that produces a fish-like odour. In most people, TMA is rapidly oxidised by the liver enzyme FMO3 into an odourless form. However, individuals with a common genetic variation that reduces FMO3 activity metabolise TMA more slowly, leading to a build-up that can cause noticeable body odour or a fishy breath. This is harmless but can be socially uncomfortable. Reducing the dose or splitting it across two smaller servings may help manage this in affected individuals.

Not exactly, though they are related. Beetroot extract is a whole-food supplement that contains multiple active compounds, including dietary nitrates (which boost nitric oxide via a different pathway to citrulline or arginine) and betaine. Betaine Anhydrous is the isolated trimethylglycine compound extracted and concentrated for supplementation. Beetroot extract is primarily used for its nitrate content and NO-boosting effects; betaine anhydrous is used for its methylation, osmolytic, and strength benefits. They are complementary rather than interchangeable.

Yes — consistent daily intake is important because betaine works through chronic physiological adaptation rather than an acute pre-workout effect. Much like creatine, its benefits depend on maintaining elevated tissue levels over time. Skipping rest days will slow the rate at which methylation support, cellular hydration, and creatine synthesis benefits accumulate. A simple approach is to take your daily 2.5g dose at the same time each day regardless of whether you train.

There is some evidence that betaine can support favourable body composition changes — specifically, studies have found reductions in fat mass alongside increases in lean mass with 2.5g per day over six weeks. The mechanism is not fully understood but may involve effects on fat metabolism through its role in methylation. That said, betaine is not a fat burner in the conventional stimulant sense — any fat loss effect is modest and should be viewed as a secondary benefit alongside its primary performance applications.

Yes — betaine anhydrous and trimethylglycine (TMG) are the same compound. Betaine is the common name used in the food and supplement industry; TMG is the more chemically precise name describing its structure (glycine with three methyl groups attached). The anhydrous designation simply means it is in a dehydrated, water-free form — which is the standard supplement formulation. If you see either name on a label, they refer to the same ingredient.

Creatine has a larger and more consistent body of evidence behind it and is generally considered the stronger of the two for strength and power. Betaine’s evidence base is growing but smaller, and effect sizes in research are typically more modest. That said, the two are not in competition — their mechanisms are complementary, and betaine’s unique contributions (methylation support, homocysteine reduction, osmolytic hydration) offer benefits that creatine does not. For most athletes, the optimal approach is to use both together rather than choosing between them.