Low-Moderate Protein Diets Lacking Carnosine

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Mech Ageing Dev. 2005 Oct;126(10):1034-9.

Glycation, ageing and carnosine: are carnivorous diets

beneficial?

Hipkiss AR.

Centre for Experimental Therapeutics, Harvey

Research Institute, Vane Science Centre, Bart's

and the London Queen 's School of Medicine and

Dentistry, Charterhouse Square, London EC1M 6BQ, UK.

alanandjill@...

Non-enzymic protein glycosylation (glycation) plays

important roles in ageing and in diabetes and its

secondary complications. Dietary constituents may play

important roles in accelerating or suppressing

glycation. It is suggested that carnivorous diets

contain a potential anti-glycating agent, carnosine

(beta-alanyl-histidine), whilst vegetarians may lack

intake of the dipeptide. The possible beneficial

effects of carnosine and related structures on protein

carbonyl stress, AGE formation, secondary diabetic

complications and age-related neuropathology are

discussed.

Publication Types:

Review

PMID: 15955546 [PubMed - in process]

J Agric Food Chem. 2005 Jun 15;53(12):4736-9.

Quantitation of carnosine in humans plasma after

dietary consumption of beef.

Park YJ, Volpe SL, Decker EA.

Department of Food Science, Chenoweth Lab, University

of Massachusetts, Amherst, Massachusetts 01003, USA.

Carnosine (beta-alanyl-L-histidine) is a dipeptide

found in the muscle foods that has been postulated to

be a bioactive food component. The objective of this

research was to determine the concentration of

carnosine in human plasma after ingestion of beef.

Nine males and nine females were recruited for the

study. Food devoid of meat products was given to the

subjects so that they did not consume carnosine for 48

h prior to the test. Subjects fasted for 12 h and then

had blood withdrawn prior to a meal containing 200 g

of ground beef. Additional blood samples were

collected over the following 24 h and carnosine

concentrations were determined by HPLC. The cooked

ground beef used in the study contained 52% water, 24%

protein, 22% fat, and 124 mg of carnosine/100 g of

beef. No plasma carnosine was detected in subjects

before the consumption of the beef. Carnosine was

detected in plasma 15 min after beef consumption.

Plasma carnosine concentrations continued to increase

with a maximum (32.7 mg of carnosine/L of plasma)

being recorded 2.5 h after consumption. Carnosine

concentrations then decreased until no carnosine could

be detected at 5.5 h postconsumption. These results

indicate that dietary carnosine is absorbed into human

plasma after the consumption of beef. Since carnosine

has several potential health benefits, evidence of its

bioavailability suggests that it could be a bioactive

food component.

PMID: 15941308 [PubMed - indexed for MEDLINE]

Physiol Res. 2002;51(3):313-6.

Advanced glycation end products and nutrition.

Krajcovicova-Kudlackova M, Sebekova K, Schinzel R,

Klvanova J.

Institute of Preventive and Clinical Medicine,

Bratislava, Slovak Republic.

Advanced glycation end products (AGEs) may play an

important adverse role in process of atherosclerosis,

diabetes, aging and chronic renal failure. Levels of

N(epsilon)-carboxymethyllysine and fluorescent AGE

values were estimated in two nutritional population

groups--alternative group (vegetarians--plant food,

milk products, eggs) and traditional group (omnivorous

subjects). Vegetarians have a significantly higher

carboxymethyllysine content in plasma and fluorescent

AGE values. Intake of proteins, lysine and

monosaccharides as well as culinary treatment,

consumption of food AGEs (mainly from technologically

processed products) and the routes of Maillard

reaction in organism are the substantial sources of

plasma AGEs. Vegetarians consume less proteins and

saccharides. Lysine intake is significantly reduced

(low content in plant proteins). Subjects on

alternative nutrition do not use high temperature for

culinary treatment and consume low amount of

technologically processed food. Fructation induced AGE

fluorescence is greater as compared with that induced

by glucose. It is due to higher participation of a

more reactive acyclic form of fructose. Intake of

vegetables and fruit with predominance of fructose is

significantly higher in vegetarians. Comparison of

nutrition and plasma AGEs in vegetarian and omnivorous

groups shows that the higher intake of fructose in

alternative nutrition of healthy subjects may cause an

increase of AGE levels.

PMID: 12234125 [PubMed - indexed for MEDLINE]

Eur J Nutr. 2001 Dec;40(6):275-81.

Plasma levels of advanced glycation end products in

healthy, long-term vegetarians and subjects on a

western mixed diet.

Sebekova K, Krajcoviova-Kudlackova M, Schinzel R,

Faist V, Klvanova J, Heidland A.

Institute of Preventive and Clinical Medicine,

Bratislava, Slovak Republic. sebekova@...

BACKGROUND: Evidence indicates that food-derived

Maillard's reaction products are absorbed and yet can

be detected in the circulation. AIM OF THE STUDY: We

postulated that consumption of the heat-treated food

by omnivores could be reflected by higher plasma

levels of advanced glycation end products (AGEs) in

comparison with vegetarians, who in cooking (by

keeping away from meat) use lower temperatures and

less time for heating. METHODS: Plasma fluorescent

AGEs (350/450 nm) and N(epsilon)-(carboxymethyl)lysine

(CML, competitive ELISA) levels were investigated in 3

groups of healthy vegetarians (9 vegans-V, 19

lactoovo-vegetarians--VLO and 14 semi-vegetarians--VS)

and compared with those of age-matched omnivores (O,

n=19). Mean duration of vegetarian diet was V: 7.2 +/-

1.0,VLO: 8.2 +/- 0.8 and VS: 7.9 +/- 1.1 years.

RESULTS: Both fluorescent AGE (O: 9.9 +/- 0.5; V: 10.8

+/- 0.7, LO: 13.1 +/- 0.8* and SV: 11.6 +/- 1.2 x

10(3) AU), and CML levels (O: 427.1 +/- 15.0,V: 514.8

+/- 24.6*, LO: 525.7 +/- 29.5**, SV: 492.6 +/- 18.0*

ng/ml) were significantly lower in omnivores than in

vegetarians. Plasma glucose, parameters of renal

function (plasma concentration of creatinine and

cystatin C, calculated glomerular filtration

rate--GFR) as well as C-reactive protein levels were

within the normal range and did not differ

significantly between the groups. Thus, neither

decline of kidney function nor inflammatory processes

contributed to the rise in plasma AGEs. CONCLUSION:

Enhanced plasma AGE levels in vegetarians in

comparison to omnivores are herein presented for the

first time. Mechanisms of AGE elevation and potential

pathophysiological relevance of this finding are to be

elucidated in prospective studies.

PMID: 11876491 [PubMed - indexed for MEDLINE]

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