AGELESS PRIORITY - Durk Pearson & Sandy Shaw's® Life Extension Newsletter™

According to a recent paper(1), twenty million adults in the UI.S. 20 years or older have an increased serum creatinine level (creatinine is cleared by the kidneys)  and the incidence increases with age.  The paper further notes that more than 20% of those age 65 years or older have decreased kidney function, even when corrected for obvious causes of kidney dysfunction such as  hypertension and diabetes.  Moreover, there is a strong association between age-associated chronic kidney disease and cardiovascular disease, since inflammatory mechanisms are involved in both.(1)  Surprisingly, "results from a  longitudinal study of normal aging adults in Italy showed that the most significant correlation with mortality was the level of renal function." (1,1b)

Hence, if you have reached 65 years of age, having successfully avoided being done in prematurely by cardiovascular disease and cancer, declining kidney function is a major factor to consider in all-cause mortality and you should have your kidney functions tested regularly as part of your health assessment.

Declining kidney function in aging is associated with increased levels of the cytokine IL-6, C-Reactive Protein, and other markers of inflammation and oxidative   stress. Importantly, increasing quantities of serum AGEs  accumulate in the kidneys and impair their function.  In a recent paper(1), the authors refer to studies showing that reducing AGEs in the  diet of both animals and humans (by, for example, cooking foods at a lower temperature) is one effective way of reducing serum AGEs and  protecting  kidney function.  Other ways (not discussed in this  paper) include dietary supplements of nutrients that decrease the formation of AGEs or interfere with the pathways of damage initiated by AGEs.

Serum Advanced Glycation End Products (AGEs) Associated with Kidney Function Decline

The kidneys are the major way the body has for  excreting AGEs to maintain the body load of AGEs at nontoxic levels.(1)  It has been shown that during aging and in diabetes, the glomerular basement membrane of the kidneys are thickened, leading to less efficient kidney filtration.(2)  (Interestingly, thickening of the  basement membrane of other organs, such as the testes,  also occurs with aging.)   This thickening has been  linked to glycosylation  (an early part of the process that produces AGEs) of the collagen type IV that makes up more than 80% of the glomerular basement membrane material.(2)

AGE inhibitors have been reported to provide significant protection against cardiovascular disease as  well as age-associated decline in kidney function.

Reducing Accumulation of AGEs in Kidneys with L-Arginine

The amino acid L-arginine has been shown to be a reducer of cross-linking in aging collage type IV and is strongly associated with  a reduction of collagen  accumulation of N-epsilon-(carboxymethyl)lysine (an AGE) in aging mice and in diabetic mice.(2)

Another paper attests to the kidney protective effects of l-arginine.(3)  12-13 month old rats treated for 8 months with l-arginine had their glomerular filtration rate increased by 50% as compared  with  untreated controls.  Another study (4) reported that 12  week old hyperlipidemic hyperglycemic Golden Syrian hamsters had enhanced accumulation of fluorescent AGE-proteins in the vascular mesenteric bed and in the lens, which was decreased significantly by l-arginine treatment.

References

(1) Vlassara et al, "Identifying advanced glycation end  products as a major source of oxidants in aging: implications for the management and/or prevention of reduced renal function in elderly persons," SEMINARS IN NEPHROLOGY 29(6):594-603 (2009)

(1b)  Pizzarelli  et al, "Predictivity of survival  according to different equations for estimating renal function in community-dwelling elderly subjects," NEPHROL. DIAL. TRANSPLANT.  24:1197-1205 (2009)

(2)   Radner   et  al, "L-arginine reduces kidney  collagen accumulation and N-epsilon(carboxymethyl)lysine in the aging NMRI-mouse," JOURNAL OF GERONTOLOGY: MEDICAL SCIENCES  49(2):M44-M46 (1994)

(3) Reckelhoff et al, "Long-term dietary supplementation with l-arginine prevents age-related reduction in renal function,"  AM. J. PHYSIOL. 272 (REGULATORY INTEGRATIVE COMP. PHYSIOL. 41):R1768-R1774 (1997)

(4) Georgescu and Popov, "Age-dependent accumulation of  advanced glycation endproducts is accelerated in combined  hyuperlipidemia and hyperglycemia, a process attenuated by l-arginine," J.  AMER. AGING ASSOC. 23:33-40 (2000)