It has been suggested in the literature that consumption in the diet of methionine – an amino acid such as in animal protein may have a negative effect on healthspan and potentially lifespan.
It has also been suggested that dietary restriction (DR) of methionine is a good lifestyle choice for healthy aging.
This presents a problem for those of us that are omnivores and include quality animal protein in our diets.
A suggested solution to this quandary is to consume supplemental glycine, a readily available and inexpensive amino acid.
Following are representative abstracts on these topics.
It is worth noting that with respect to cancer that glycine may stimulate growth so dietary glycine restriction may be of benefit.
Prog Mol Biol Transl Sci. 2014;121:351-76. doi: 10.1016/B978-0-12-800101-1.00011-9.
The impact of dietary methionine restriction on biomarkers of metabolic health.
Orgeron ML1, Stone KP1, Wanders D1, Cortez CC1, Van NT1, Gettys TW1.
Abstract
Calorie
restriction without malnutrition, commonly referred to as dietary
restriction (DR), results in a well-documented extension of life span.
DR also produces significant, long-lasting improvements in biomarkers of
metabolic health that begin to accrue soon after its introduction. The
improvements are attributable in part to the effects of DR on energy
balance, which limit fat accumulation through reduction in energy
intake.
Accumulation of excess body fat occurs when energy intake chronically
exceeds the energy costs for growth and maintenance of existing tissue.
The resulting obesity promotes the development of insulin resistance,
disordered lipid metabolism, and increased expression of inflammatory
markers in peripheral tissues. The link between the life-extending
effects of DR and adiposity is the subject of an ongoing debate, but it
is clear that decreased fat accumulation improves insulin sensitivity
and produces beneficial effects on overall metabolic health. Over the
last 20 years, dietary methionine restriction (MR) has emerged as a
promising DR mimetic because it produces a comparable extension in life
span, but surprisingly, does not require food restriction.
Dietary MR also reduces adiposity but does so through a paradoxical
increase in both energy intake and expenditure. The increase in energy
expenditure fully compensates for increased energy intake and
effectively limits fat deposition. Perhaps more importantly, the diet
increases metabolic flexibility and overall insulin sensitivity and
improves lipid metabolism while decreasing systemic inflammation. In
this chapter, we describe recent advances in our understanding of the
mechanisms and effects of dietary MR and discuss the remaining obstacles
to implementing MR as a treatment for metabolic disease.
KEYWORDS:
Amino acid sensing; Animal models; Dietary protein; Insulin sensitivity; Obesity
Biochemistry/Molecular Biology
Dietary glycine supplementation mimics lifespan extension by dietary methionine restriction in Fisher 344 rats
Joel Brind,Virginia Malloy,Ines Augie,Nicholas Caliendo,Joseph H Vogelman,Jay A. Zimmerman, and Norman Orentreich
Abstract
Dietary
methionine (Met) restriction (MR) extends lifespan in rodents by 30–40%
and inhibits growth. Since glycine is the vehicle for hepatic clearance
of excess Met via glycine N-methyltransferase (GNMT), we hypothesized
that dietary glycine supplementation (GS) might produce biochemical and
endocrine changes similar to MR and also extend lifespan. Seven-week-old
male Fisher 344 rats were fed diets containing 0.43% Met/2.3% glycine
(control fed; CF) or 0.43% Met/4%, 8% or 12% glycine until natural
death.
In 8% or 12% GS rats, median lifespan increased from 88 weeks (w) to 113
w, and maximum lifespan increased from 91 w to 119 w v CF. Body growth
reduction was less dramatic, and not even significant in the 8% GS
group. Dose-dependent reductions in several serum markers were also
observed. Long-term (50 w) 12% GS resulted in reductions in mean (±SD)
fasting glucose (158 ± 13 v 179 ± 46 mg/dL), insulin (0.7 ± 0.4 v 0.8 ±
0.3 ng/mL), IGF-1 (1082 ± 128 v 1407 ± 142 ng/mL) and triglyceride (113 ±
31 v 221 ± 56 mg/dL) levels compared to CF.
Adiponectin, which increases with MR, did not change in GS after 12 w on
diet. We propose that more efficient Met clearance via GNMT with GS
could be reducing chronic Met toxicity due to rogue methylations from
chronic excess methylation capacity or oxidative stress from generation
of toxic by-products such as formaldehyde. This project received no
outside funding.
