Trimethylglycine, commonly called TMG or betaine, shows up in the highest concentrations in beets, spinach, quinoa, whole grains, and shellfish. The compound is widespread across the food supply, but a handful of foods stand out as genuinely rich sources, while most others contain only trace amounts. Because typical dietary intake falls well below the levels associated with measurable health benefits, knowing which foods pack the most TMG per serving matters more than simply knowing it exists in your diet.
The Standout Plant Sources
Beetroot is probably the food most associated with TMG, and for good reason. The compound’s formal chemical name, betaine, literally derives from the Latin name for beets (Beta vulgaris). Beets, along with spinach and whole grains, consistently rank among the most common dietary sources of betaine in food-composition studies.1PubMed Central. Betaine as a Functional Ingredient: Metabolism, Health-Promoting Attributes, Food Sources, Applications and Analysis Methods Silverbeet (chard) also appears in the same category.2Food Chemistry. Glycine betaine and glycine betaine analogues in common foods
Quinoa deserves special mention. Analyses of its betaine content have returned values ranging from roughly 3,900 to 6,300 micrograms per gram, which puts it in the same league as wheat bran and far ahead of most other plant foods.3PubMed Central. Betaine in Cereal Grains and Grain-Based Products That is a strikingly high concentration for a pseudocereal that many people eat primarily for its protein or fiber content. If you are specifically trying to boost TMG through food, quinoa is one of the most efficient options available.
Spinach rounds out the trio of top plant sources. Raw spinach contains meaningful amounts of TMG per serving, and because it is easy to eat in large volumes when cooked down, it can contribute substantially to daily intake. Other leafy greens contain some betaine but generally fall well short of spinach’s levels.
Grain Products and Why Bread Counts
Whole grains and grain-based products are where many people get the bulk of their dietary TMG without realizing it. Wheat flour, bread, and pasta all contain betaine at levels above 150 micrograms per gram.4Elsevier / Journal of Food Composition and Analysis. The betaine content of New Zealand foods and estimated intake in the New Zealand diet That might not sound impressive compared to quinoa, but grain products make up such a large share of most diets that they become significant contributors through sheer volume. A person eating several slices of whole-grain bread and a serving of pasta in a day is taking in a non-trivial amount of TMG from grains alone.
The betaine in grains is concentrated in the bran layer, so refined flour has less than whole-grain flour. This is one of those cases where the generic nutrition advice to “choose whole grains” has a specific biochemical payoff. White bread still contains some TMG, but whole-wheat bread contains considerably more.
One interesting wrinkle involves sourdough. Metabolic profiling of sourdough-fermented bread has shown that certain betaine-related compounds, including amino acid-derived betaines like trimethyllysine and valine betaine, decrease during the fermentation process.5PubMed Central. Metabolic profiling of sourdough fermented wheat and rye bread That does not necessarily mean all glycine betaine is lost in sourdough, but it is a reminder that processing and fermentation can alter the betaine profile of a food in ways that a simple ingredient list would never tell you.
Shellfish and Seafood
Shellfish are among the richest animal sources of TMG, and betaine is one of the reasons crustaceans taste the way they do. In shrimp, crab, and lobster, betaine contributes to the characteristic sweet-umami flavor profile alongside amino acids like glycine and proline.6Journal of Agricultural and Food Chemistry. Sensomics-Assisted Elucidation of the Tastant Code of Cooked Crustaceans and Taste Reconstruction Experiments Analyses of Chinese shrimp, for example, found betaine at about 65 milligrams per 100 grams of tissue, a level high enough to meaningfully influence taste.7International Journal of Food Science and Technology. Characterisation of taste-active compositions, umami attributes and aroma compounds in Chinese shrimp
The reason shellfish accumulate so much betaine is biological, not dietary. Marine crustaceans and mollusks use betaine as an osmolyte, a molecule that helps their cells manage water balance in salty environments. When shrimp are raised in higher-salinity water, betaine concentrations in their muscle tissue, gills, and other organs go up.8PubMed. Effect of salinity on the synthesis and concentration of glycine betaine in osmoregulatory tissues from juvenile shrimps Litopenaeus vannamei This means wild-caught shellfish from saltier ocean waters may contain somewhat more TMG than farmed shrimp raised in dilute ponds, though the practical difference for your diet is hard to pin down without testing individual batches.
Flour and other shellfish-adjacent seafood also appear in food-composition databases as betaine sources, though finfish generally contain less than crustaceans and mollusks.2Food Chemistry. Glycine betaine and glycine betaine analogues in common foods
How Much TMG Do People Actually Eat?
Across populations worldwide, daily betaine intake from food typically falls somewhere between 100 and 300 milligrams. Where you land in that range depends heavily on your cuisine. Studies of U.S. cohorts have found intakes of roughly 130 to 215 milligrams per day, with men generally eating more than women. European women in a large prospective study reported a median of about 112 milligrams per day. Japanese diets, which tend to include more grain products and seafood, push higher, with estimates of 240 to 350 milligrams per day.9Scientific Reports. Association between dietary betaine intake and overweight or obesity
Those numbers sit well below the threshold that research suggests is needed for clear health effects. Some researchers have pointed to 1.5 grams per day as a target for expected health benefits, which is five to fifteen times what most people consume through food alone.9Scientific Reports. Association between dietary betaine intake and overweight or obesity That gap is why TMG supplements exist and why some people turn to concentrated beetroot powder or juice. Getting 1.5 grams purely from whole foods would require eating an unrealistic quantity of beets or spinach every single day.
Still, the 100-to-300-milligram range from a varied diet is not nothing. Food-derived betaine may contribute to baseline methylation and cellular functions even at these lower doses, and the compound has been shown to lower homocysteine at intakes in the range of what a healthy diet provides.
What TMG Does Once You Eat It
TMG has two main jobs in your body. First, it acts as an osmolyte, helping cells maintain their volume and hydration under stress. This is especially important in the kidneys, where cells in the inner medulla face extremely high and variable salt concentrations as part of the urine-concentrating process. These cells accumulate betaine to balance the osmotic pressure without disrupting their internal machinery.10PubMed. Osmoregulation of betaine transport in mammalian renal medullary cells The same protective mechanism operates in other tissues under stress conditions, contributing to cellular integrity more broadly.11PubMed Central. Betaine as a regulator of metabolism, epigenetics, and cellular osmoprotection: therapeutic implications in cardiometabolic and renal diseases
Second, and arguably more studied, TMG serves as a methyl donor. It hands off a methyl group to convert homocysteine back into methionine, an essential amino acid. This reaction is catalyzed by a specific enzyme, betaine-homocysteine methyltransferase, and it operates as an alternative pathway to the better-known folate-dependent route.12PubMed. Betaine: a key modulator of one-carbon metabolism and homocysteine status The practical significance is that TMG can help keep homocysteine levels in check even when folate intake is not optimal.
TMG and Homocysteine
Elevated homocysteine in the blood is considered a risk marker for cardiovascular disease, and TMG’s ability to lower it is one of the best-supported effects of the compound. A meta-analysis of clinical trials found that betaine supplementation reduced plasma homocysteine by an average of about 1.2 micromoles per liter.13PubMed Central. Betaine supplementation decreases plasma homocysteine in healthy adult participants: a meta-analysis In individual trials, supplementation at around 6 grams per day lowered fasting homocysteine by up to 20 percent and blunted the post-meal spike in homocysteine by as much as half.14PubMed. Effects of betaine intake on plasma homocysteine concentrations and consequences for health
One controlled trial in healthy adults tested a more modest supplementation level and found that six weeks of betaine supplementation reduced fasting homocysteine by about 11 percent compared to placebo. Folic acid supplementation in the same trial lowered it by about 18 percent. But betaine had an advantage that folic acid did not: it also suppressed the homocysteine surge that occurs after eating a protein-rich meal.15The Journal of Nutrition. Betaine Supplementation Lowers Plasma Homocysteine in Healthy Men and Women This finding suggests that TMG and folate work through complementary pathways, and that having both in your diet may be more effective than relying on one alone.
Whether lowering homocysteine through TMG translates directly into fewer heart attacks or strokes is a separate question, and the evidence there is less definitive. But homocysteine reduction is a plausible mechanism, and it is well-established that TMG achieves it reliably.
The TMAO Concern
If you have read about gut health and heart disease, you may have encountered TMAO, or trimethylamine N-oxide, a metabolite that some research has linked to cardiovascular risk. TMG is one of the dietary precursors that gut bacteria can convert into trimethylamine, which the liver then oxidizes into TMAO.16PubMed Central. Trimethylamine N-Oxide: The Good, the Bad and the Unknown Choline and carnitine are the other major precursors.
This creates what looks like a paradox: TMG lowers homocysteine, which should be cardioprotective, but it can also be converted into TMAO, which some studies have associated with increased cardiovascular risk. The picture is still being sorted out. TMAO levels depend not just on what you eat but on the specific composition of your gut microbiome, your kidney function, and how much of the betaine your body uses directly for methylation before gut bacteria get a chance at it. People who eat a lot of seafood, for instance, tend to have higher TMAO levels but do not consistently show worse cardiovascular outcomes, which suggests the relationship between TMAO and disease is more complicated than early studies implied.
For someone eating normal amounts of TMG-rich foods, this is not something to lose sleep over. The TMAO concern is more relevant in the context of high-dose supplementation or very high red meat and egg intake, where carnitine and choline contribute more to the TMAO pool than betaine does.
TMG in Sports Supplements
You will find TMG in many pre-workout and sports-nutrition products, typically dosed at 1.25 to 2.5 grams per serving. The rationale is that betaine’s osmolyte properties could help muscles retain water and resist fatigue, and its role in methylation might support creatine synthesis. The evidence is mixed. Some studies have found improvements in lower-body strength and power output with betaine supplementation, and the compound is gaining traction as a potential ergogenic aid, particularly for strength and endurance training.17PubMed Central. Betaine (TMG) as a Dietary Supplement in Sports – Mechanisms of Action, Ergogenic Effects, and Safety of Use
In one trial, participants who took betaine showed improved bench press training volume compared to a placebo group at certain points in the training cycle, along with a trend toward improved vertical jump power, though the overall performance differences between groups did not reach strong statistical significance across all measures.18PubMed Central. Effects of betaine on body composition, performance, and homocysteine thiolactone The effects seem most reliable for lower-body power and less consistent for upper-body strength or endurance measures. Large-scale trials are still lacking, so calling TMG a proven performance enhancer would be premature, but it is not snake oil either.
Why These Foods Contain So Much TMG in the First Place
The foods richest in TMG tend to be organisms that face osmotic stress in their natural environments. Beets and spinach grow in soils that can become quite salty. Quinoa is famously tolerant of drought and saline soils. Shellfish live in seawater. The common thread is that betaine serves these organisms the same way it serves your kidney cells: as an osmolyte that protects cellular structures when water balance is challenged.
In plants, glycine betaine accumulates in response to salt stress, drought, and temperature extremes. It stabilizes proteins, protects photosynthetic machinery, and helps cells hold onto water.19PubMed Central. Compatible solute engineering in plants for abiotic stress tolerance – role of glycine betaine Research on crops like maize has shown that applying betaine externally to salt-stressed plants improves their growth, chlorophyll content, and membrane stability.20Notulae Botanicae Horti Agrobotanici Cluj-Napoca. Glycine-betaine induced salinity tolerance in maize by regulating the physiological attributes, antioxidant defense system and ionic homeostasis This understanding has led agricultural researchers to investigate betaine as a crop treatment for improving yields in drought- and salt-prone regions.
Marine animals use betaine for a parallel purpose. The extremely salty and osmotically demanding environment of ocean water means crustaceans and mollusks need potent osmolytes to prevent their cells from shrinking. Some species, like certain sea slugs, rely on related betaine compounds rather than the usual amino-acid-based osmoregulation that most marine invertebrates use.21PubMed. Proline Betaine: A Unique Osmolyte in an Extremely Euryhaline Osmoconformer
TMG in Animal Agriculture
An area most people never think about is the widespread use of betaine as a feed additive in livestock and poultry production. Farmers add TMG to animal feed primarily to combat heat stress, which is a growing problem as global temperatures rise. Betaine’s ability to bind water molecules and prevent cellular dehydration makes it useful for keeping animals productive in hot conditions.22The Indian Journal of Animal Sciences. Betaine: A potent feed additive for amelioration of adverse effect of heat stress in livestock and poultry In pig farming, it has also been used as a growth promoter.
A meta-analysis of dairy cattle studies found that supplementing betaine in heat-stressed cows increased their dry matter intake by about 0.58 kilograms per day, a meaningful bump for an animal whose productivity depends on eating enough.23PubMed Central. Effects of betaine supplementation on dry matter intake, milk characteristics, plasma non-esterified fatty acids, and β-hydroxybutyric acid in dairy cattle: a meta-analysis Individual studies have found that betaine-fed dairy cows produced more milk under normal temperatures, though the benefit sometimes disappeared during actual heat stress, suggesting the relationship is more nuanced than a simple “add betaine, get more milk” equation.24PubMed. Evaluation of dietary betaine in lactating Holstein cows subjected to heat stress
The agricultural use of betaine is worth knowing about because it highlights just how fundamental this molecule’s stress-protective function is across the biological world. The same compound that helps a beet plant survive salty soil, helps a shrimp regulate water in the ocean, and helps your kidneys concentrate urine is also helping dairy cows eat normally in a heat wave. That kind of cross-kingdom conservation hints at how ancient and essential betaine’s biochemistry really is.