Trimethylglycine (TMG) — also referred to as betaine or betaine anhydrous — is an important compound that your body can produce by itself. It is also found in supplements and certain foods.

TMG has been studied for many potential health benefits, including the ability to enhance heart health, boost athletic performance, promote healthy insulin levels, and protect against depression.

However, it may also cause side effects, especially if used in high doses.

This article covers TMG benefits, side effects, dosage, and how to increase your intake with food.

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TMG is a compound that consists of glycine with three attached methyl groups.

It’s produced by your body and is found naturally in beetroot and other foods. It’s also available as a supplement, sometimes used to enhance athletic performance and improve heart and liver health.

TMG is involved in a chemical process called methylation, which is essential for DNA production (1).

It also converts homocysteine — a type of amino acid, the building blocks of protein — into another compound called methionine. This is beneficial since high levels of homocysteine can damage your blood vessels and increase heart disease risk (2, 3).

summary

TMG is a compound produced by your body. It’s also found in foods and available in supplement form. It’s involved in methylation and can help prevent high levels of homocysteine in your blood.

TMG supplements may be associated with several health benefits.

May lower homocysteine levels to improve heart health

Some research shows that TMG could decrease blood levels of homocysteine, a type of amino acid found in your blood. Too high levels of this compound can increase your risk of heart disease (3).

A 2013 review of 5 studies showed that taking at least 4 grams of TMG per day for 6 weeks could lower blood levels of homocysteine in healthy adults (4).

Another review had similar findings, noting that taking 4 grams of TMG per day lowered homocysteine levels without negatively impacting other aspects of heart health, like blood pressure or triglyceride levels (5).

On the other hand, some studies — both older and newer — have shown that TMG supplements could increase levels of total and LDL (bad) cholesterol in the blood, both of which are risk factors for heart disease (6, 7).

Ultimately, more research is needed on how these supplements may affect heart health.

Could improve athletic performance

Many athletes use TMG supplements with the aim of enhancing exercise performance.

One review reported that TMG supplements could improve body composition and enhance performance in both endurance- and resistance-type exercises (8).

Although the exact mechanisms are unclear, researchers speculate that TMG may (8):

  • reduce fatigue
  • boost protein production
  • increase the synthesis of creatine, a compound that provides energy to your muscle cells

Another review of seven studies turned up mixed results. Still, it noted that in two studies, TMG supplements significantly increased muscle strength and power (9).

Meanwhile, several other studies show that TMG has no impact on exercise performance or strength. That’s why more studies are needed before experts can confidently recommend TMG as an athleticism-boosting supplement (10, 11, 12).

May prevent insulin resistance

Several studies have found that TMG supplements could improve insulin resistance, a condition that impairs your body’s ability to use the hormone insulin to regulate blood sugar levels (13).

For example, a study in nearly 2,400 people associated a higher intake of choline and betaine with decreased insulin resistance (14).

Plus, in an animal study, administering TMG supplements to mice on a high fat diet improved fat metabolism and decreased insulin resistance (15).

What’s more, one mouse study from 2010 found that TMG supplements could reverse insulin resistance in the liver. This is when insulin isn’t effective at suppressing sugar production in the liver (16).

Still, more research is needed to better understand how TMG may affect insulin resistance in humans.

Could improve depression

Some research shows that TMG supplements could improve how well certain types of antidepressant medications work.

In particular, TMG has been shown to increase the effects of S-adenosyl-methionine (SAMe), a type of medication used to treat mild to moderate depression (17, 18).

Interestingly, in a small study including 64 people with depression, those who took both SAMe and TMG for 12 months experienced greater improvement in their symptoms than those who took SAMe alone (19).

What’s more, this supplement may also improve symptoms of depression and anxiety. That’s because these conditions may be linked with elevated homocysteine levels that TMG could help lower (20, 21, 22).

summary

Some studies suggest that TMG could decrease homocysteine levels, boost athletic performance, improve insulin resistance, and enhance the effectiveness of certain antidepressants.

The most common side effects associated with TMG supplements are digestive issues that include:

  • diarrhea
  • indigestion
  • bloating
  • cramps
  • nausea
  • vomiting

These are more common if you’re taking higher doses of the supplement (2).

In rare cases, TMG could also significantly increase the amount of methionine — a type of amino acid — in your blood, which could cause fluid buildup around the brain (2).

If you experience any side effects from taking this supplement, discontinue use and talk with your doctor.

TMG supplements are not recommended for children and those who are pregnant or breastfeeding, as there is limited research on its safety and long-term effects on health.

summary

TMG supplements can cause digestive side effects. In rare cases, they could cause high blood levels of methionine, which can be life threatening. Children and those who are pregnant or breastfeeding should avoid using them.

There are no official dosage recommendations for these supplements, but most products provide 750–3,000 mg of TMG per serving.

TMG is considered safe when used in doses up to 15 grams per day (23).

Most studies on the potential benefits of TMG supplements in humans have used amounts of 500–9,000 mg per day, typically divided into several smaller doses (8).

If you have any underlying health conditions or are taking other medications, talk with your doctor before taking a TMG supplement and use them only as directed.

summary

Most supplements contain 750–3,000 mg of TMG per serving. It’s generally been studied in doses of 500–9,000 mg per day. Doses up to 15 grams per day are considered safe.

In addition to taking a supplement, you can increase your intake of TMG naturally, as it’s found in many foods. Wheat, beets, quinoa, and seafood are particularly rich sources (24).

Here’s the amount of TMG found in a 3.5-ounce (100-gram) serving of several foods (24, 25, 26):

  • Wheat bran: 1,339 mg
  • Wheat germ: 1,241 mg
  • Spinach: 600–645 mg
  • Quinoa: 390 mg
  • Beets: 114–297 mg
  • Shrimp: 219 mg
  • Wheat bread: 201 mg

Keep in mind that several factors impact the amount of TMG found in foods. For example, certain cooking methods, particularly boiling, significantly decrease the TMG content (24).

summary

TMG is found in many foods, including wheat bran, wheat germ, quinoa, spinach, and beets.

TMG is a compound that’s produced by your body. It’s also found in supplements and certain foods.

Although more research is needed, some studies in humans and animals suggest that it could:

  • lower homocysteine levels
  • improve athletic performance
  • protect against insulin resistance
  • enhance the effectiveness of certain antidepressants

In addition to taking a supplement, you can increase your intake of TMG by enjoying a variety of nutrient-dense foods, including beetroot, quinoa, spinach, and wheat bran.