Researchers tested whether a diet high in methionine (an amino acid found in protein) could help diabetic rats. They found something surprising: the diet actually helped reduce fat buildup in the liver, which is usually a problem in diabetes. However, the same diet seemed to harm the kidneys by increasing a harmful substance called homocysteine. This study shows that what helps one part of your body might hurt another part, so people with diabetes may need different nutritional strategies for different organs.

The Quick Take

  • What they studied: Whether eating extra methionine (a building block of protein) could help or hurt rats with diabetes, especially in their liver and kidneys
  • Who participated: 32 male rats divided into four groups: healthy rats, healthy rats eating extra methionine, diabetic rats, and diabetic rats eating extra methionine. Each group had 8 rats and the study lasted 12 weeks
  • Key finding: High-methionine diet cut liver fat in half in diabetic rats (from 42 to 21 units), but it appeared to increase kidney damage by raising a harmful chemical called homocysteine
  • What it means for you: This suggests that while methionine supplements might help protect the liver in diabetes, they could potentially harm the kidneys. Anyone considering methionine supplements should talk to their doctor first, especially if they have diabetes or kidney problems

The Research Details

Scientists used laboratory rats to test how a high-methionine diet affected diabetes. They created diabetes in some rats using a chemical called streptozotocin, which damages the pancreas similar to how Type 1 diabetes develops in humans. They then divided the rats into four groups: normal rats, normal rats eating extra methionine, diabetic rats, and diabetic rats eating extra methionine. The rats ate these diets for 12 weeks while researchers measured changes in their liver, kidneys, and blood.

This type of study is called an animal model study. Scientists use it to understand how something might work in the human body before testing it in people. The researchers measured specific chemicals and fats in the liver and kidneys to see what changed.

Animal studies help scientists understand how nutrients affect different organs before testing in humans. This research is important because it shows that one nutrient can have opposite effects in different parts of the body—helping one organ while potentially harming another. This finding could change how doctors think about recommending supplements to diabetic patients.

This study used a controlled laboratory setting with identical conditions for all rats, which is good for reliability. However, rat studies don’t always translate directly to humans because rats’ bodies work differently than ours. The study was relatively small (32 rats total) and only lasted 12 weeks, so longer studies in humans would be needed to confirm these findings. The researchers measured specific markers in the tissue, which is a reliable method.

What the Results Show

The most striking finding was that the high-methionine diet had opposite effects in two organs. In the liver, it significantly reduced fat accumulation—cutting the amount of triglycerides (a type of fat) nearly in half. This happened because methionine activated a protein called AMPK that helps the body burn fat more efficiently.

However, in the kidneys, the high-methionine diet appeared to cause problems. It increased levels of homocysteine, a chemical that can damage blood vessels and kidney tissue. This suggests the kidneys were struggling to process the extra methionine properly.

The diabetic rats that received the high-methionine diet showed these effects more strongly than healthy rats eating the same diet. This indicates that diabetes changes how the body handles methionine, making it more likely to cause kidney problems.

The study also measured other metabolic markers (chemical signs of how the body is working). The high-methionine diet appeared to change how the body processed amino acids and managed energy in diabetic rats. These changes were specific to each organ, suggesting that different tissues respond differently to the same nutrient.

Previous research suggested that methionine might help with weight management and liver health. This study confirms that methionine can help reduce liver fat, but it reveals a previously underappreciated risk: potential kidney damage through homocysteine buildup. This adds important nuance to earlier findings and suggests that methionine’s benefits aren’t universal across all organs.

This study was conducted in rats, not humans, so results may not apply directly to people. The study only lasted 12 weeks, which is relatively short for understanding long-term effects. The sample size was small (32 rats), which limits how confident we can be in the results. The study didn’t test different doses of methionine, so we don’t know if lower amounts might be safer. Finally, the study didn’t measure all possible effects on kidney function, only homocysteine levels.

The Bottom Line

Based on this research, high-dose methionine supplements are not recommended for people with diabetes without medical supervision (low confidence, animal study only). If you have diabetes and are considering methionine or amino acid supplements, consult your doctor first, especially if you have any kidney problems. For general health, getting methionine from regular protein sources (meat, eggs, dairy) is safer than taking supplements.

People with diabetes should pay attention to this research, especially those considering amino acid or methionine supplements. People with kidney disease or kidney problems should be particularly cautious. Healthy people without diabetes probably don’t need to worry about this, as the problems appeared mainly in diabetic rats. Anyone taking amino acid supplements should discuss this research with their healthcare provider.

In the rat study, kidney problems appeared within 12 weeks. If similar effects occur in humans, they might develop over weeks to months of supplementation. However, we don’t know the actual timeline in people. Benefits to the liver (if they occur) might also take weeks to develop.

Want to Apply This Research?

  • If using a nutrition app, track daily methionine intake from food sources and any supplements. Log kidney function markers (if you have recent lab work) and any symptoms like changes in urination, swelling, or fatigue. Monitor liver health markers if available from your doctor’s visits.
  • Instead of taking methionine supplements, focus on eating balanced protein from varied sources (chicken, fish, beans, eggs, dairy). Use the app to track total protein intake and ensure you’re getting enough without excessive supplementation. If you have diabetes, work with your doctor to set appropriate protein targets.
  • For people with diabetes considering methionine supplementation: have kidney function tests (creatinine and eGFR) done before starting and every 3 months during use. Track homocysteine levels if your doctor recommends it. Monitor liver health through regular check-ups. Keep a symptom log in your app noting any changes in energy, urination patterns, or swelling.

This research was conducted in laboratory rats and has not been tested in humans. The findings suggest potential risks with high-methionine supplementation in diabetes, but human studies are needed to confirm these effects. Do not start, stop, or change any supplements or medications based on this research alone. If you have diabetes, kidney disease, or are considering methionine supplements, consult your healthcare provider before making any changes. This information is for educational purposes only and should not replace professional medical advice.