title: Association of homocysteine levels with blood lead levels and micronutrients in the US general population.
abstract: OBJECTIVE
  Even though several epidemiological studies have observed positive associations between blood lead levels and homocysteine, no study has examined whether this association differs by the levels of micronutrients, such as folate, vitamin B6, and vitamin B12, which are involved in the metabolism of homocysteine. In this study, we examined the interactions between micronutrients and blood lead on homocysteine levels.
  
  
  METHODS
  This study was performed with 4089 adults aged ≥20 years old in the US general population using the National Health and Nutrition Examination Survey 2003-2004.
  
  
  RESULTS
  There were significant or marginally significant interactions between micronutrients and blood lead levels on mean homocysteine levels. Positive associations between blood lead and homocysteine were clearly observed among subjects with low levels of folate or low vitamin B6 (p-trend <0.01, respectively). However, in the case of vitamin B12, there was a stronger positive association between blood lead and homocysteine among subjects with high levels of vitamin B12, compared to those with low levels of vitamin B12. In fact, the levels of homocysteine were already high among subjects low in vitamin B12, irrespective of blood lead levels. When we used hyperhomocysteinemia (homocysteine>15 µmol/L) as the outcome, there were similar patterns of interaction, though p-values for each interaction failed to reach statistical significance.
  
  
  CONCLUSIONS
  In the current study, the association between blood lead and homocysteine differed based on the levels of folate, vitamin B6, or vitamin B12 present in the blood. It may be important to keep sufficient levels of these micronutrients to prevent the possible harmful effects of lead exposure on homocysteine levels.
authors.affiliation: Department of Preventive Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Yu-Mi
authors.initials: YM
authors.lastname: Lee
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Lee
authors.forename: Sang-Geun
authors.initials: SG
authors.lastname: Bae
authors.forename: Seon-Hwa
authors.initials: SH
authors.lastname: Lee
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Duk-Hee
authors.initials: DH
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007854:Lead / Q000097:blood*; D008297:Male; D018977:Micronutrients / Q000097:blood*; D008875:Middle Aged; D009749:Nutrition Surveys; D016017:Odds Ratio; D014481:United States; D014805:Vitamin B 12 / Q000097:blood; D025101:Vitamin B 6 / Q000097:blood
chemical_list: D018977:Micronutrients; D006710:Homocysteine; D007854:Lead; D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12