Glycine may prevent/treat diabetic neuropathy

[haidut]

A very interesting study, which adds more evidence in favor of the recent hypothesis that glycine (just as taurine) is in fact an essential amino acid. Namely, despite our ability to synthesize glycine, as needed, from the truly essential amino acids, its absence in the diet leads to pathologies even in healthy organisms - i.e. in this case neuropathy. Conversely, adding the glycine back to the diet (at a HED of 3g-4g daily) prevented and reversed the neuropathy in both healthy and diabetic organisms.

Insulin-regulated serine and lipid metabolism drive peripheral neuropathy - Nature
A diet high in amino acids reduced diabetes-related nerve pain in mice

"...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/glycine-enriched diet or a standard diet for eight weeks, after which, those in the serine/glycine 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/glycine 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/glycine supplements, as more research is needed to establish a safe dosage and potential side effects, he says. 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."

 

[Tom K]

While not questioning the role of amino acids, I have begun to question the relevance of using nocturnal animals for determining intervention outcomes. I mention this questioning/doubt for a few reasons. First, the circadian influence on health outcomes (shift workers for example) is well established. It is not too big of a stretch to question the experimentation on a lab animal that is naturally active at night, because the majority of what occurs with these animals' interventions occurs during the day. At the least, the experimental interventions should occur at night in alignment with their normal circadian pattern.

As we learn more about the effect of light on human physiology, we should not rule out this influence on lab animals. The artificial light environments in which the rodent subjects are maintained are probably an influence on their physiology and behavior. Every lab I have been in uses fluorescent tubes to illuminate the environment. Fluorescents are high in blue light at levels to which the animals would never be exposed in their natural habitat. Using the mouse model is much less expensive than the ape model, it is more socially acceptable, and easier to manage. However, the ape model also has similar flaws. Though not nocturnal by nature, the blue light saturated environment in which they are held affects their SCN related structures as well.

 

[lamassu]

Good find