title: Dietary garlic and hip osteoarthritis: evidence of a protective effect and putative mechanism of action.
abstract: BACKGROUND
  Patterns of food intake and prevalent osteoarthritis of the hand, hip, and knee were studied using the twin design to limit the effect of confounding factors. Compounds found in associated food groups were further studied in vitro.
  
  
  METHODS
  Cross-sectional study conducted in a large population-based volunteer cohort of twins. Food intake was evaluated using the Food Frequency Questionnaire; OA was determined using plain radiographs. Analyses were adjusted for age, BMI and physical activity. Subsequent in vitro studies examined the effects of allium-derived compounds on the expression of matrix-degrading proteases in SW1353 chondrosarcoma cells.
  
  
  RESULTS
  Data were available, depending on phenotype, for 654-1082 of 1086 female twins (median age 58.9 years; range 46-77). Trends in dietary analysis revealed a specific pattern of dietary intake, that high in fruit and vegetables, showed an inverse association with hip OA (p = 0.022). Consumption of 'non-citrus fruit' (p = 0.015) and 'alliums' (p = 0.029) had the strongest protective effect. Alliums contain diallyl disulphide which was shown to abrogate cytokine-induced matrix metalloproteinase expression.
  
  
  CONCLUSIONS
  Studies of diet are notorious for their confounding by lifestyle effects. While taking account of BMI, the data show an independent effect of a diet high in fruit and vegetables, suggesting it to be protective against radiographic hip OA. Furthermore, diallyl disulphide, a compound found in garlic and other alliums, represses the expression of matrix-degrading proteases in chondrocyte-like cells, providing a potential mechanism of action.
authors.affiliation: Dept Twin Research and Genetic Epidemiology, King's College London, London, UK. frances.williams@kcl.ac.uk
authors.forename: Frances M K
authors.initials: FM
authors.lastname: Williams
authors.forename: Jane
authors.initials: J
authors.lastname: Skinner
authors.forename: Tim D
authors.initials: TD
authors.lastname: Spector
authors.forename: Aedin
authors.initials: A
authors.lastname: Cassidy
authors.forename: Ian M
authors.initials: IM
authors.lastname: Clark
authors.forename: Rose M
authors.initials: RM
authors.lastname: Davidson
authors.forename: Alex J
authors.initials: AJ
authors.lastname: MacGregor
mesh_terms: D000368:Aged; D000498:Allyl Compounds / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002813:Chondrosarcoma / Q000378:metabolism / Q000473:pathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D004220:Disulfides / Q000494:pharmacology; D005260:Female; D005737:Garlic; D006801:Humans; D016015:Logistic Models; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000517:prevention & control*; D010447:Peptide Hydrolases / Q000378:metabolism; D010936:Plant Extracts / Q000008:administration & dosage / Q000627:therapeutic use*; D011859:Radiography
chemical_list: D000498:Allyl Compounds; D004220:Disulfides; D010936:Plant Extracts; C028009:diallyl disulfide; D010447:Peptide Hydrolases; D020782:Matrix Metalloproteinases