BetaineAmino Acid

• Plasma homocysteineLikely helps

  Betaine's clearest human effect: it donates a methyl group, turning homocysteine back into methionine [3].
  
  A 6-week dose-ranging trial in healthy adults found fasting homocysteine down 12% at 1.5g/day, 15% at 3g/day and 20% at 6g/day, all significant against placebo [2].
  
  A separate meta-analysis in healthy adults puts the drop at 5–20% for 6 g/day [3]. ^[2]

• Cardiovascular riskPossibly helps

  Lowering homocysteine is a biomarker strategy, not a demonstrated outcome.
  
  The estimate behind it is that a 5 µmol/L drop in homocysteine corresponds to 20–30% lower cardiovascular disease risk [2]. No trial has shown that betaine supplementation itself reduces heart attacks or strokes. ^[2]

• Homocystinuria — prescription useLikely helps

  Betaine anhydrous is FDA-approved as an orphan drug for homocystinuria, a rare inherited disorder of homocysteine metabolism [6].
  
  It typically brings blood homocysteine down to 20–30% of pretreatment values [6]. Dosing is individualized by a physician monitoring plasma homocysteine and methionine [7]. ^[6]

• Athletic performancePossibly helps

  Genuinely mixed, and the sources say so. Most controlled trials find no benefit to maximal strength or power, especially at low training volumes [1].
  
  A 6-week trial in collegiate athletes at 5g/day improved half squat and overhead press but not countermovement jump, bench press or deadlift [5].
  
  Some trials report gains in high-volume protocols with heavy lactate stress, hypothesized to relate to betaine's osmolyte role [1]. One cited study found no additive benefit when betaine was combined with creatine, which shares that mechanism [1]. ^[5]

• Fatty liver (NAFLD and NASH)Possibly helps

  Unsettled in humans, despite strong animal data. In high-fat-diet mouse models betaine improved insulin sensitivity, reduced hepatic fat and limited inflammatory adipose stress [23].
  
  The largest and best-designed human RCT — 55 NASH patients, 20g/day for 12 months at Duke University — found no significant difference from placebo in ALT, AST, NAFLD activity score or fibrosis stage [8].
  
  A case-control study did find NASH patients carry significantly lower betaine levels than people with simple fatty liver [9]. That is an association in one patient group, not evidence that low betaine drives the disease. ^[8]

• A citation discrepancy in that NASH trialPossibly helps

  ⚠ Worth knowing if you go looking at the primary literature yourself.
  
  Some citation records of the 2009 Duke trial (Hepatology 2009;50:1818-26) say betaine improved hepatic steatosis. The corrected version, after a 2010 erratum, says it did not [8].
  
  LiverTox and the primary PubMed record carry the corrected, more conservative reading, which is what we use here [7]. ^[8]

• Body fatPossibly helps

  A meta-analysis of 6 RCTs (195 participants) found betaine supplementation significantly reduced body fat [23].
  
  Observational data put plasma betaine inversely related to body fat percentage, and a 2024 study linked higher dietary betaine intake to lower body weight, BMI and waist circumference [16]. ^[16]

• Betaine HCl for low stomach acidPossibly helps

  Different compound, different claim — see Forms. Betaine hydrochloride measurably lowers stomach pH when taken with or just before a meal [10].
  
  A 2020 academic review states the popular escalate-until-you-feel-warmth titration protocol has never been rigorously tested in a controlled setting [10]. What exists is limited pharmacokinetic data plus widespread anecdotal clinical use. ^[10]

• Betaine anhydrous (TMG, trimethylglycine)Methylation and homocysteine work.

  Elemental content

  CAS 107-43-7, C5H11NO2, 117.15 g/mol — the pure, non-acidic compound [11]

  Absorption

  Peak plasma at a median of 0.90 hours after a 50 mg/kg oral dose; absolute oral bioavailability has never been formally determined [11]

  Best for

  Methylation and homocysteine work. The same molecule as the prescription drug Cystadane [11]

• Betaine hydrochloride (betaine HCl)Gastric acidification, not methylation.

  Elemental content

  Betaine bonded to hydrochloric acid; releases about 0.65 mmol of H+ per 100 mg in water [10]

  Absorption

  Works in the stomach rather than systemically, so it has to arrive alongside food [10]

  Best for

  Gastric acidification, not methylation. Contraindicated outright in peptic ulcer disease and gastritis [18]

• Digestive effects

  The most consistently reported effect, and it scales with dose: nausea, diarrhoea, stomach cramps, bloating [1].
  
  This is an osmotic effect, the same thing other osmolytes do at high intake [17]. ^[1]

• Cerebral edema at prescription doses

  Specific to homocystinuria patients with cystathionine beta-synthase (CBS) deficiency, not to over-the-counter use.
  
  Excessive rises in plasma methionine have been linked to life-threatening cerebral edema, so methionine is monitored throughout betaine anhydrous therapy [6]. ^[6]

• Blood lipids

  A narrative review of randomized trials found 4g/day or more raises total and LDL cholesterol, with no significant change in HDL or triglycerides and no effect on liver enzymes [15].
  
  ⚠ The population boundary is unresolved. One review reports the effect specifically in overweight, obese and metabolic-syndrome participants [23]; the pooled-RCT review does not draw that line [15]. ^[15]

• Body odour — a plausible pathway, no documented cases

  Body odour is listed as a reported adverse effect for the prescription drug betaine anhydrous [17].
  
  Gut bacteria can convert betaine into trimethylamine (TMA), the compound behind the fishy smell in trimethylaminuria [23]. But that condition is usually a genetic FMO3 defect, and Cleveland Clinic's list of supplement triggers names choline and carnitine — not betaine [22].
  
  No controlled study or case report links ordinary TMG supplementation to odour in people with normal FMO3 function. ^[23]

• NSAIDs and corticosteroids with betaine HCl

  Combining betaine HCl with NSAIDs or corticosteroids raises GI bleeding and ulcer risk [18].
  
  Other standing rules from the same sources: never on an empty stomach, never open the capsule, and stop immediately if burning occurs [10]. ^[18]

• Antacids and acid-suppressing drugs — betaine HCl only

  Betaine hydrochloride raises stomach acid while H2-blockers and antacids lower it, so they work directly against each other [18].
  
  Betaine HCl is separately contraindicated in active peptic ulcer disease and gastritis [20]. ^[18]

• Thyroid hormone medication — betaine HCl only

  A patient-education source flags that betaine HCl's acid effect could increase absorption of thyroid hormone medication in people with low stomach acid [18].
  
  That is a mechanistic expectation, not a documented adverse event. ^[18]

• Statins — not pharmacological, but directional

  The FDA label for betaine anhydrous states there are no known, well-documented, clinically significant drug-drug interactions [6].
  
  Still worth knowing if you take a statin: multiple RCTs show 4g/day or more of betaine raising total and LDL cholesterol, the markers the statin is there to lower [15]. ^[6]

Wheat and other cereal grains, beets, and spinach are the biggest contributors to dietary betaine in Western diets [12].

Wheat bran runs 2,300–7,200 µg/g and wheat germ 3,414 µg/g [12]. Amaranth recorded the single highest value of any food tested, 7,420 µg/g, with quinoa close behind at 3,930–6,300 µg/g [12].

Those two are the best non-wheat, gluten-free sources identified [12].

Milling costs you most of it: refined grain products measure 2 to 4 times lower than their wholegrain versions, because betaine concentrates in the bran and aleurone layer [12].

Betaine is heat-stable, holding together until above 245°C, so baking, cooking and extrusion leave most of it intact [12].

⚠ Average intake estimates disagree by roughly 5–15x, and we are not picking a winner.

A US multiethnic cohort of 188,147 people found 154 mg/day in men and 128 mg/day in women [14]. A pooled review of 28 observational studies found 182 mg/day [15]; a landmark Dutch dosing study estimated 500–2,000 mg/day [2].

Later USDA database revisions lowered betaine values for grains, spinach and seafood, which may be why the newer cohort figures run lower [12].

Betaine is not choline, though the two are linked. Choline concentrates in red meat, poultry, seafood, eggs and dairy, and the body converts part of it to betaine [13].

For plain betaine or TMG, nothing rigorous exists. The trials behind the homocysteine effect specify a total daily dose, sometimes split in two, but no clock time and no fasted-or-fed requirement [2].

The FDA label for Cystadane says to dissolve each dose in 120–180 mL of water, milk or juice and take it immediately after mixing, twice a day [6]. That is an administration instruction for a drug, not a timing optimization.

Betaine hydrochloride is the exception, and its rule is firm: with or immediately before a meal, one of roughly 500+ calories with protein [10]. Taken on an empty stomach it causes burning and produces false readings in the self-titration protocol some clinicians use [18].

Whether either form affects sleep, or works better morning versus evening, is unstudied in everything we read.