title: Effects of 28 days of dairy or soy ingestion on skeletal markers of inflammation and proteolysis in post-menopausal women.
abstract: BACKGROUND
  Aging is associated with increased local inflammation and resultant proteolysis in skeletal muscle. In animal models, soy supplementation is a beneficial countermeasure against muscle inflammation and proteolysis; however, the effect on aging humans is not clear.
  
  
  METHODS
  A single-blinded, randomized, controlled trial was conducted on 31 post-menopausal women. Volunteers were randomly assigned to consume three servings of soy (n=16) or dairy (n=15) milk each day for 28 days. The expression of inflammation-responsive (TNF-α, IL-1β, IL-6) and proteolytic (calpain 1, calpain 2, ubiquitin, E2, atrogin-1, muRF-1) genes in skeletal muscle was determined using real-time polymerase chain reaction before and after supplementation, and then after a downhill run performed to elicit muscle damage.
  
  
  RESULTS
  While no group by time interactions were observed, significant main effects for time were observed for IL-1β, IL-6, calpain 2, and atrogin-1 mRNA post exercise. Further analysis revealed that, compared with post-supplementation values, calpain 2 and atrogin-1 mRNA significantly increased at 4 h post exercise (p=0.01 and p<0.01, respectively), whereas IL-1β and IL-6 mRNA significantly decreased at 4 h post exercise (both p<0.01).
  
  
  CONCLUSIONS
  Soy or dairy milk supplementation at the amount ingested for 28 days does not appear to preferentially inhibit the expression of inflammation-responsive and proteolytic genes that were assessed, and does not attenuate the eccentric exercise-induced up-regulation in the proteolytic genes.
authors.affiliation: University of Maryland School of Medicine, Baltimore, MD, USA. Darryn_Willoughby@baylor.edu
authors.forename: Monica C
authors.initials: MC
authors.lastname: Serra
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Beavers
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Beavers
authors.forename: Darryn S
authors.initials: DS
authors.lastname: Willoughby
mesh_terms: D000375:Aging / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D003611:Dairy Products; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D017698:Postmenopause / Q000378:metabolism*; D059748:Proteolysis; D012333:RNA, Messenger / Q000378:metabolism; D012420:Running; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D016037:Single-Blind Method; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D053583:Interleukin-1beta; D015850:Interleukin-6; D009124:Muscle Proteins; D012333:RNA, Messenger; D030262:Soybean Proteins; D025801:Ubiquitin; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; D002154:Calpain; C569870:CAPN2 protein, human