Betaine (Trimethylglycin) Explained Simply

1. What It Is About

Betaine is a substance that the body produces itself and which we take in through food. It is found in beetroot, quinoa, spinach and whole-grain cereals. In the body, betaine has two roles. First, it stabilises the interior of cells so that they do not dry out or swell. Second, it passes on small building blocks that the body needs for many conversion processes. These building blocks are called methyl groups. Betaine is processed in the liver and kidneys and excreted in the urine. Its role in handling homocysteine is particularly important. Homocysteine is a protein building block in the blood. A high level is considered an indicator of risk for the heart and blood vessels. Betaine helps the body to convert homocysteine. In studies, betaine is examined in two ways: as an endogenous substance measured in the blood and as an administered substance in trials. Many studies only measure laboratory values. They do not show whether people actually feel better or fall ill less often. This is important for correctly interpreting the results.

2. What Studies Show

The clearest effect is on homocysteine levels. A summary of five controlled studies involving a total of 195 participants found that betaine lowers homocysteine levels in the blood when administered in higher amounts over several weeks 3. A smaller study in ten healthy adults showed that larger amounts significantly lowered the level, while the smallest tested amount had no effect 2. The substance is therefore quickly absorbed, and the effect depends on the amount.

In people with chronic kidney disease, i.e. permanently impaired kidney function, betaine was tested together with folic acid and vitamin B6. After a test meal containing the amino acid methionine, the homocysteine level was significantly lower than without betaine. The fasting level, however, remained unchanged 1. This suggests that betaine mainly has an effect when the metabolism is under strain.

In young handball players, betaine was tested over two weeks. The players were then able to perform more repetitions in leg press and bench press than with a placebo. The cortisol level after training was also lower. Cortisol is a stress hormone of the body. The testosterone level remained unchanged 5. A further summary of six studies involving 195 participants found that betaine reduced body fat percentage, while weight and body mass index remained the same 4.

In 55 patients with non-alcoholic fatty liver disease, betaine was tested over twelve months. Liver fat decreased. However, inflammatory markers in the blood and the extent of scarring of the liver tissue did not change 6.

3. What Remains Unclear

Most studies measure laboratory values such as homocysteine. They do not show whether people thereby suffer fewer heart attacks or live longer. Large studies with folic acid have lowered homocysteine levels without reducing heart attacks or strokes. Whether this is different with betaine remains to be seen.

A complicating factor is that betaine is often administered together with folic acid, vitamin B12 or vitamin B6. It is then difficult to determine which share of the effect comes from betaine itself. Many studies are also small and only run for a few weeks. Studies in people with kidney disease or rare metabolic disorders cannot easily be transferred to healthy people. The effects of long-term intake over years have only been examined to a limited extent so far.

4. What This Means in Everyday Life

Betaine is a well-researched substance with a plausible role in metabolism. The best-established effect is that it lowers homocysteine levels. Whether this laboratory value is the right target is itself a matter of debate in research. After all, a lowered level does not automatically mean less disease.

The indications of greater endurance, less body fat or reduced liver fat come from individual, mostly small studies. They are interesting, but have not yet been confirmed by several independent studies. Anyone interested in the topic can find the exact details on participants, duration and measured variables in the cited studies. The next step would be to clarify whether betaine has the same effects in people without kidney disease and whether this translates into anything for the course of the disease.

All details with study numbers and sources: detailed page on betaine (trimethylglycine). For children: Betaine (trimethylglycine) for children