Association of Homocysteine Levels With Blood Lead Levels and Micronutrients in the US General Population

Abstract

ObjectivesEven 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.MethodsThis 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.ResultsThere 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.ConclusionsIn 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.

Effect of occupational exposure to lead on new risk factors for cardiovascular diseases

“…Based on NHANES 2003–2004 raw data, the difference in plasma Hcy concentrations between the group with the lowest concentration of Pb (mean 8 µg/L) and the group with the highest concentration of Pb in the blood (mean 72 µg/L) was 63%. After adjusting the data for age, sex, race/ethnicity, poverty to income ratio, BMI, smoking, alcohol consumption and physical activity, the difference in Hcy levels remained highly significant but decreased to 22% 28. A similar relationship between Pb concentration in the blood and Hcy was observed in a study on a subcohort within the Veterans Affairs Normative Aging Study 29.…”

Exposure to Toxic Heavy Metals Can Influence Homocysteine Metabolism?

“…The range of Pb blood levels in the general population was from 0.93 (0.77-1.05) to 35 Pollak and colleagues [21], in an investigation carried out among women in reproductive age, demonstrated that blood Pb levels were correlated with increases in Hc among women consuming lower levels of essential Vitamin B 12 and folate. This was similar to Lee et al [27], who observed stronger associations between Pb and Hc among adult people with lesser serum values of Vitamin B 6 and folate. In a longitudinal study, Bakulski and colleagues [25] observed older men and described that Pb and Hc were more strongly correlated among men with a lower concentration of Vitamin B 12 and folate.…”

“…All studies of this review support that Pb concentrations are correlated with high levels of Hc [9,[21][22][23][24][25][26][27][28][29][30].…”

“…Twelve were ruled out a subsequent review of title and abstract, and 26 studies were disqualified after review of the manuscript. In conclusion, 16 studies satisfied the inclusion criteria and were included in the systematic review [6,[21][22][23][24][25][26][27][28][29][30][31][32]. A flowchart depicting the choice of studies is revealed in Figure 1.…”

Blood lead levels, iron metabolism gene polymorphisms and homocysteine: a gene-environment interaction study

“…Genetic polymorphisms in the TF gene can induce changes in iron distribution, haeme synthesis and activity of CBS, a haeme-containing enzyme that metabolises homocysteine into cystathionine in a transsulfuration pathway, resulting in a gradient in homocysteine levels 39–41. Although lead may also decrease haeme and haemoglobin synthesis and CBS activity, additional synergistic increases associated with lead exposure may not occur at high levels of homocysteine, possibly because of the already-low CBS activity 19. However, mechanistic evidence directly supporting the present observation is limited, and further studies focusing on the suggested pathway are warranted.…”