Posted 26 August 2007 - 08:45 PM
a study in 2003 came out stating there was a weak correelation of beta-casein to atherogenesis...later that year they released:
Atherosclerosis. 2003 Sep;170(1):11-2. Links
Comment on:
Atherosclerosis. 2003 Sep;170(1):13-9.
Beta-casein variants and atherosclerosis-claims are premature.
In 2006:
Atherosclerosis. 2006 Sep;188(1):175-8. Epub 2005 Nov 18. Links
A comparison of the effects of A1 and A2 beta-casein protein variants on blood cholesterol concentrations in New Zealand adults.Venn BJ, Skeaff CM, Brown R, Mann JI, Green TJ.
Department of Human Nutrition, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Beta-casein is a cow's milk protein that occurs predominantly in two forms, A1 and A2. Epidemiological evidence suggests that per capita consumption of beta-casein A1 is associated with national mortality rates from ischaemic heart disease. A biological mechanism was proposed after rabbits fed diets containing beta-casein A2 had lower serum cholesterol concentrations and less aortic intimal thickening than rabbits fed beta-casein A1. We tested whether beta-casein A1 and A2 variants differentially affect plasma cholesterol concentrations in humans. In a randomised crossover trial of two four-and-a-half week periods without washout, 62 participants replaced all dairy products in their diet with 500 mL of low-fat milk and 28 g of full-fat cheese that differed in the proportion of beta-casein A1 and A2 variants. Duplicate blood samples were taken on non-consecutive days at the end of each treatment period from 55 people who completed the study. Mean (S.D.) plasma total, low-density and high-density lipoprotein cholesterol concentrations were 5.60 (0.77), 3.73 (0.70) and 1.26 (0.34) mmol/L after the A1 diet and 5.63 (0.81), 3.75 (0.75) and 1.27 (0.37) mmol/L after the A2 diets. We found no evidence that dairy products containing beta-casein A1 or A2 exerted differential effects (P > 0.05) on plasma cholesterol concentrations in humans.
I've flipped through 10-15 studies from the peer-reviewed journals and they state no eefect on cholesterol, atherogenesis, lipoproteins, there are studies with growth/development (positive), reversing tumor growth, reduction of diabetic symptoms, improved immune function, and increased bone mineral density.
I found studies with rats (above with humans) that showed reduction of inflammtion via TGF-beta.
Here's a study showing the synergy of milk proteins:
Am J Clin Nutr. 2006 Nov;84(5):1070-9. Links
Comment in:
Am J Clin Nutr. 2007 Jun;85(6):1664; author reply 1664-5.
Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement.Lacroix M, Bos C, Léonil J, Airinei G, Luengo C, Daré S, Benamouzig R, Fouillet H, Fauquant J, Tomé D, Gaudichon C.
UMR INRA 914, Physiology of Nutrition and Feeding Control Unit, Institut National Agronomique Paris-Grignon, Paris, France.
BACKGROUND: The in vivo quality of milk protein fractions has seldom been studied in humans. OBJECTIVE: Our objective was to compare the postprandial utilization of dietary nitrogen from 3 [(15)N]-labeled milk products: micellar caseins (MC), milk soluble protein isolate (MSPI), and total milk protein (TMP). DESIGN: The macronutrient intakes of 23 healthy volunteers were standardized for 1 wk, after which time the subjects ingested a meal containing MC (n = 8), MSPI (n = 7), or TMP (n = 8). [(15)N] was measured for an 8-h period in plasma amino acids, proteins, and urea and in urinary urea. RESULTS: The transfer of dietary nitrogen to urea occurred earlier after MSPI ingestion than after MC and TMP ingestion, and concentrations remained high for 8 h, concomitantly with higher but transient hyperaminoacidemia and a higher incorporation of dietary nitrogen into plasma amino acids. In contrast, deamination, postprandial hyperaminoacidemia, and the incorporation of dietary nitrogen into plasma amino acids were lower in the MC and TMP groups. Finally, total postprandial deamination values were 18.5 +/- 2.9%, 21.1 +/- 2.8%, and 28.2 +/- 2.9% of ingested nitrogen in the TMP, MC, and MSPI groups, respectively. CONCLUSIONS: Our results confirm the major role of kinetics in dietary nitrogen postprandial utilization and highlight the paradox of MSPI, which, despite its high Protein Digestibility Corrected Amino Acid Score, ensures a rate of amino acid delivery that is too rapid to sustain the anabolic requirement during the postprandial period. Milk proteins had the best nutritional quality, which suggested a synergistic effect between soluble proteins and caseins.
PMID: 17093159 [PubMed - indexed for MEDLINE
And for bodybuilding/weight training:
1: Med Sci Sports Exerc. 2004 Dec;36(12):2073-81. Links
Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise.Tipton KD, Elliott TA, Cree MG, Wolf SE, Sanford AP, Wolfe RR.
Metabolism Unit, Shriners Hospitals for Children and Department of Surgery, The University of Texas Medical Branch, Galveston, TX 77550, USA. ktipton@utmb.edu
PURPOSE: Determination of the anabolic response to exercise and nutrition is important for individuals who may benefit from increased muscle mass. Intake of free amino acids after resistance exercise stimulates net muscle protein synthesis. The response of muscle protein balance to intact protein ingestion after exercise has not been studied. This study was designed to examine the acute response of muscle protein balance to ingestion of two different intact proteins after resistance exercise. METHODS: Healthy volunteers were randomly assigned to one of three groups. Each group consumed one of three drinks: placebo (PL; N = 7), 20 g of casein (CS; N = 7), or whey proteins (WH; N = 9). Volunteers consumed the drink 1 h after the conclusion of a leg extension exercise bout. Leucine and phenylalanine concentrations were measured in femoral arteriovenous samples to determine balance across the leg. RESULTS: Arterial amino acid concentrations were elevated by protein ingestion, but the pattern of appearance was different for CS and WH. Net amino acid balance switched from negative to positive after ingestion of both proteins. Peak leucine net balance over time was greater for WH (347 +/- 50 nmol.min(-1).100 mL(-1) leg) than CS (133 +/- 45 nmol.min(-1).100 mL(-1) leg), but peak phenylalanine balance was similar for CS and WH. Ingestion of both CS and WH stimulated a significantly larger net phenylalanine uptake after resistance exercise, compared with the PL (PL -5 +/- 15 mg, CS 84 +/- 10 mg, WH 62 +/- 18 mg). Amino acid uptake relative to amount ingested was similar for both CS and WH (approximately 10-15%). CONCLUSIONS: Acute ingestion of both WH and CS after exercise resulted in similar increases in muscle protein net balance, resulting in net muscle protein synthesis despite different patterns of blood amino acid responses.
PMID: 15570142 [PubMed
I've personally spoke to some of these men about this study and they've done more research since. I believe in whey/ casein.
My ultimate protein is whey isolate and micellar casein 50/50. Xtreme Formulations is a company that does this pre-flavored/pre-done. True Protein and Protein Factory could do this as well.