Eating more of the amino acids serine and glycine decreased the amount of nerve damage and pain in mice with diabetes
25 January 2023
Dietary supplements of the amino acid serine may ease diabetes-related nerve pain, according to research in mice.
Nearly half of people with diabetes have neuropathy – a condition in which nerve damage causes weakness, pain and numbness, usually in the hands and feet.
Christian Metallo at the Salk Institute for Biological Studies in La Jolla, California, and his colleagues measured levels of protein-building molecules called amino acids in obese mice genetically engineered to have either type 1 or type 2 diabetes.
They found that, compared with mice without either condition, those with diabetes had, on average, lower levels of the amino acids serine and glycine in their tissues and blood plasma. Further analysis suggested this is because insulin is necessary for preventing the breakdown of those amino acids.
The team then fed 10 non-diabetic mice a diet without serine or glycine for a year and 10 non-diabetic mice a standard diet. On average, the mice in the first group were slower to retract a paw from a heated laser than those in the other group, indicating greater nerve damage. When viewed under a microscope, their paws also had reduced nerve fibre density, suggesting that serine and glycine deficiencies contribute to neuropathy.
A separate group of 17 mice with type 2 diabetes ate either a serine-enriched diet or a standard diet for eight weeks, after which, those in the serine group retracted their paw from the laser about 1 second faster, on average, than those in the control group.
These findings suggest that increasing serine levels either through dietary supplements or targeted drugs could improve the condition, says Metallo. However, people with diabetic neuropathy shouldn’t rush to grab serine supplements, as more research is needed to establish a safe dosage and potential side effects, he says. The researchers also looked at glycine supplementation in a separate study but haven’t published the results yet.
The findings also suggest we may need to rethink how we view certain nutrients. “Serine and glycine are non-essential amino acids, so we consume them in our diet, but we can also produce them within the body,” says Metallo, meaning levels are rarely monitored closely. “But this highlights that the metabolism of non-essential amino acids can [also] cause defects.”
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