X-Message-Number: 25032
Date: Sat, 13 Nov 2004 21:39:59 -0800 (PST)
From: Doug Skrecky <>
Subject: some benefits of a low-AGE diet

[A diet low in Advanced Glycation End-products (AGE) may offer many of
the same benefits as a low calorie diet, but without the hunger.]

[Lowering AGE the hard way.]

J Physiol Anthropol Appl Human Sci. 2004 Jan;23(1):19-24
Calorie restricted diet and urinary pentosidine in patients with
rheumatoid arthritis.
  Low-energy diets and fasting have suppressive effects on rheumatoid
arthritis. It was reported recently that urine levels of pentosidine
(i.e., an advanced glycation end product formed by glycosylation) is
associated with the activity of rheumatoid arthritis. We conducted a
regimen of caloric restriction combined with fasting in patients with
rheumatoid arthritis, and then evaluated urinary pentosidine levels. Ten
patients with rheumatoid arthritis underwent a 54-day caloric restriction
program. Urinary pentosidine levels were measured and the Lansbury Index
were determined by examining the clinical features, blood biochemistry and
the inflammation activity of rheumatoid arthritis on days 0, 25 and 54.
On day 0, the mean urinary pentosidine level of patients with rheumatoid
arthritis was significantly higher than that of the control subjects. On
day 54, the mean body weight had reduced due to caloric restriction. The
mean values of the erythrocyte sedimentation rate and the Lansbury Index
of patients both significantly decreased during the study. In addition,
although the urinary pentosidine levels showed no significant difference
between day 0 and 25, it was significantly decreased at the end of the
study (day 54). The study showed that under a low energy diet a reduction
of disease activity in rheumatoid arthritis was accompanied with a
reduction of the urinary pentosidine.

[Lowering AGE the easy way.]

Am J Kidney Dis. 2003 Sep;42(3):532-8
Dietary glycotoxins correlate with circulating advanced glycation end
product levels in renal failure patients.
  BACKGROUND: Levels of advanced glycation end products (AGEs), well-known
proinflammatory compounds, are markedly elevated in patients with renal
failure, raising the speculation that they have a role as cardiovascular
risk factors in this population. Although elevated AGE levels in patients
with renal failure have been attributed to impaired renal clearance and
increased endogenous AGE formation, recent data suggest an important role
for diet as a source of AGEs. METHODS: To determine the relationship
between dietary AGE content and serum AGE levels, a cross-sectional study
was performed in our long-term dialysis patients. Dietary AGE intake was
estimated by means of dietary records and questionnaires, and sera were
obtained for measurement of 2 well-characterized AGEs,
carboxymethyl-lysine (CML) and methylglyoxal (MG) derivatives. RESULTS:
The study population included 189 patients; 139 hemodialysis and 50
peritoneal dialysis patients. Serum CML level correlated significantly
with dietary AGE intake, based on either 3-day food records (r = 0.5; P =
0.003) or dietary questionnaires (r = 0.22; P = 0.03). Although no
correlation was observed with nutrient intake (protein, fat, saturated
fat, or carbohydrate), both serum CML and MG levels correlated with blood
urea nitrogen (r = 0.2; P = 0.03 and r = 0.2; P = 0.02, respectively) and
serum albumin levels (r = 0.16; P = 0.04 and r = 0.18; P = 0.02,
respectively). CONCLUSION: Data indicate that dietary AGE content,
independently of other diet constituents, is an important contributor to
excess serum AGE levels in patients with renal failure. Moreover, the
lack of correlation between serum AGE levels and dietary protein, fat,
and carbohydrate intake indicates that a reduction in dietary AGE content
can be obtained safely without compromising the content of obligatory
nutrients.

Diabetes. 2003 Nov;52(11):2805-13.
Adverse effects of dietary glycotoxins on wound healing in genetically
diabetic mice.
  Advanced glycoxidation end products (AGEs) are implicated in delayed
diabetic wound healing. To test the role of diet-derived AGE on the rate
of wound healing, we placed female db/db (+/+) (n = 55, 12 weeks old) and
age-matched control db/db (+/-) mice (n = 45) on two diets that differed
only in AGE content (high [H-AGE] versus low [L-AGE] ratio, 5:1) for 3
months. Full-thickness skin wounds (1 cm) were examined histologically
and for wound closure. Serum 24-h urine and skin samples were monitored
for N(epsilon)-carboxymethyl-lysine and methylglyoxal derivatives by
enzyme-linked immunosorbent assays. L-AGE-fed mice displayed more rapid
wound closure at days 7 and 14 (P < 0.005) and were closed completely by
day 21 compared with H-AGE nonhealed wounds. Serum AGE levels increased
by 53% in H-AGE mice and decreased by 7.8% in L-AGE mice (P < 0.04) from
baseline. L-AGE mice wounds exhibited lower skin AGE deposits, increased
epithelialization, angiogenesis, inflammation, granulation tissue
deposition, and enhanced collagen organization up to day 21, compared
with H-AGE mice. Reepithelialization was the dominant mode of wound
closure in H-AGE mice compared with wound contraction that
prevailed in L-AGE mice. Thus, increased diet-derived AGE intake may be a
significant retardant of wound closure in diabetic mice; dietary AGE
restriction may improve impaired diabetic wound healing.

Arthritis Rheum. 2004 Apr;50(4):1207-15
Accumulation of advanced glycation end products as a molecular mechanism
for aging as a risk factor in osteoarthritis.
  OBJECTIVE: Osteoarthritis (OA) is one of the most prevalent and
disabling chronic conditions affecting the elderly. Its etiology is
largely unknown, but age is the most prominent risk factor. The current
study was designed to test whether accumulation of advanced glycation end
products (AGEs), which are known to adversely affect cartilage turnover
and mechanical properties, provides a molecular mechanism by which aging
contributes to the development of OA. METHODS: The hypothesis that
elevated AGE levels predispose to the development of OA was tested in the
canine anterior cruciate ligament transection (ACLT) model of experimental
OA. Cartilage AGE levels were enhanced in young dogs by intraarticular
injections of ribose. This mimics the accumulation of AGEs without the
interference of other age-related changes. The severity of OA was then
assessed 7 weeks after ACLT surgery in dogs with normal versus enhanced
AGE levels. RESULTS: Intraarticular injections of ribose enhanced
cartilage AGE levels approximately 5-fold, which is similar to the normal
increase that is observed in old dogs. ACLT surgery resulted in
more-pronounced OA in dogs with enhanced AGE levels. This was
observed as increased collagen damage and enhanced release of
proteoglycans. The attempt to repair the matrix damage was impaired;
proteoglycan synthesis and retention were decreased at enhanced AGE
levels. Mankin grading of histology sections also revealed more-severe OA
in animals with enhanced AGE levels. CONCLUSION: These findings
demonstrate increased severity of OA at higher cartilage AGE levels and
provide the first in vivo experimental evidence for a molecular mechanism
by which aging may predispose to the development of OA.

Diabetes. 2003 Jun;52(6):1441-8
Fetal or neonatal low-glycotoxin environment prevents autoimmune diabetes
in NOD mice.
  Advanced glycation end products (AGEs) are implicated in beta-cell
oxidant stress. Diet-derived AGE (dAGE) are shown to contribute to
end-organ toxicity attributed to diabetes. To assess the role of dAGE on
type 1 diabetes, NOD mice were exposed to a high-AGE diet (H-AGE) and to
a nutritionally similar diet with approximate fivefold-lower levels of
N(epsilon)-carboxymethyllysine (CML) and methylglyoxal-derivatives (MG)
(L-AGE). Suppression of serum CML and MG in L-AGE-fed mice was marked by
suppression of diabetes (H-AGE mice >94% vs. L-AGE mice 33% in founder
[F](0), 14% in F(1), and 13% in F(2) offspring, P < 0.006) and by a delay
in disease onset (4-month lag). Survival for L-AGE mice was 76 vs. 0%
after 44 weeks of H-AGE mice. Reduced insulitis in L-AGE versus H-AGE
mice (P < 0.01) was marked by GAD- and insulin-unresponsive pancreatic
interleukin (IL)-4-positive CD4+ cells compared with the GAD- and
insulin-responsive interferon (IFN)-gamma-positive T-cells from H-AGE
mice (P < 0.005). Splenocytes from L-AGE mice consisted of GAD- and
insulin-responsive IL-10-positive CD4+ cells compared with the
IFN-gamma-positive T-cells from H-AGE mice (P < 0.005). Therefore, high
AGE intake may provide excess antigenic stimulus for T-cell-mediated
diabetes or direct beta-cell injury in NOD mice; both processes are
ameliorated by maternal or neonatal exposure to L-AGE nutrition.

Cancer Lett. 2003 Feb 20;190(2):151-6
Genotoxicity of advanced glycation end products in mammalian cells.
  In patients with chronic renal failure, cancer incidence is enhanced.
Since levels of advanced glycation end products (AGEs) are markedly
elevated in renal insufficiency, we investigated potential effects of
various AGEs on structural DNA integrity in tubule cells. The comet-assay
was employed, a method based on the computer-aided microscopic analysis of
single cells after electrophoretic separation of their nuclear DNA.
Incubation of pig kidney LLC-PK1-cells for 24 h with AGE-BSA (AGE-bovine
serum albumin), carboxymethyllysine-BSA as well as methylglyoxal-BSA
resulted in a significant increase in DNA damage. Pretreatment of the
cells with the proteases trypsin and bromelain abolished the AGE-induced
comet-formation. This is in agreement with the idea that the observed
genotoxicity of AGEs could be receptor-mediated and that proteases
inactivate the extracellular domain of the receptor for AGEs. Binding of
AGEs to the RAGE receptor leads to an increased intracellular formation
of active oxygen species, which are known to induce DNA damage. It is
concluded that AGEs induce genotoxicity in tubule cells, which may be
involved in the enhanced cancer development in advanced kidney diseases.

Atherosclerosis. 2002 Aug;163(2):303-11
Lowering of dietary advanced glycation endproducts (AGE) reduces
neointimal formation after arterial injury in genetically
hypercholesterolemic mice.
  Restenosis remains a major cause of morbidity and mortality after
coronary angioplasty. Injury-induced inflammation, thrombosis, smooth
muscle cell (SMC) proliferation, and neointimal formation contribute to
restenosis. These events are linked to circulating glucose-derived
advanced glycation endproducts (AGE), known to promote cell proliferation,
lipid glycoxidation and oxidant stress. This study evaluates the
association between dietary AGE content and neointimal formation after
arterial injury in genetically hypercholesterolemic mice. Male,
12-week-old, apolipoprotein E-deficient (apoE(-/-)) mice were randomly
assigned to receive either a high AGE diet (HAD; AGE=15000 U/mg), or a
similar diet with ten-fold lower AGE (LAD; AGE=1500 U/mg). These mice
underwent femoral artery injury 1 week later, and were maintained on
their diets for an additional 4 weeks. At 4 weeks after injury,
significant decrease in neointimal formation was noted in LAD-fed mice.
Neointimal area, intima/media ratio, and stenotic luminal area (LA) were
less pronounced in the LAD group than the HAD group (P<0.05). These
quantitative differences were associated with a marked reduction (
approximately 56%) of macrophages in the neointimal lesions, as well as
an obvious reduction of SMC content of LAD-fed mice. The reduction of
neointimal formation in the LAD mice correlated with a approximately 40%
decrease in circulating AGE levels (P<0.0005). Immunohistochemistry also
showed a reduced ( approximately 1.5-fold) deposition of AGE in the
endothelia, SMC, and macrophages in neointimal lesions of LAD-fed mice.
These results represent the first evidence in vivo for a causal
relationship between dietary AGE and the vessel wall response to acute
injury, suggesting a significant potential for dietary AGE restriction in
the prevention of restenosis after angioplasty.

Diabetes Metab Res Rev. 2002 May-Jun;18(3):224-37
Prevention of diabetic nephropathy in mice by a diet low in glycoxidation
products.
  BACKGROUND: Reactive advanced glycation end products (AGEs), known to
promote diabetic tissue damage, occur endogenously as well as in heated
foods and are orally absorbed. The relative contribution of diet-derived
AGEs to diabetic nephropathy (DN) remains unclear. METHODS: We tested a
standard mouse food (AIN-93G) found to be rich in AGEs (H-AGE diet) in
parallel with a similar diet that contained six-fold lower AGE content
(L-AGE), but equal calories, macronutrients, and micronutrients.
Non-obese diabetic mice (NOD) with type 1 diabetes (T1D) and db/db mice
with type 2 diabetes (T2D) were randomly assigned to each formula for
either 4 or 11 months, during which time renal parameters and AGE levels
were assessed. RESULTS: Compared to the progressive DN and short survival
seen in NOD mice exposed to long-term H-AGE feeding, L-AGE-fed NOD mice
developed minimal glomerular pathology and a modest increase in urinary
albumin:creatinine ratio (p<0.005), and a significantly extended survival
(p<0.0001), consistent with lower serum (p<0.025) and kidney AGEs
(p<0.01). Also, in the 4-month study, and in contrast to the H-AGE-fed
mice, L-AGE-fed NOD and db/db mice exhibited low levels of renal cortex
TGF beta-1 (p<0.05), laminin B1 mRNA (p<0.01) and alpha 1 IV collagen
mRNA (p<0.05) and protein, in concert with reduced serum and kidney AGEs
(p<0.05, respectively). CONCLUSION: Intake of high-level, food-derived
AGEs is a major contributor to DN in T1D and T2D mice. Avoidance of
dietary AGEs provides sustained protection against DN in mice; providing
the rationale for similar studies in human diabetic patients.

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