Does dietary arsenic and mercury affect cutaneous bleeding time and blood lipids in humans?

Fish species may contain considerable amounts of trace elements, such as selenium (Se), arsenic (As), and mercury (Hg). The present study investigated the relationships between dietary intake of these elements and cutaneous bleeding time and blood lipids in 32 healthy volunteers. For 6 wk, one group (n = 11) consumed approx 250 g Se-rich fish daily, providing them with an average Se intake of 115 +/- 31 micrograms Se/d, Hg intake of 18 +/- 8 micrograms/d, and As intake of 806 +/- 405 micrograms/d, all values analyzed in 4-d duplicate food collections. To study the effect of Se alone, one group (n = 11) included Se-rich bread in their normal diet, giving them a Se intake (135 +/- 25 micrograms/d) that was comparable to the fish group. A control group (n = 10) ate their normal diet, providing 77 +/- 25 micrograms Se/d, 3.1 +/- 2.5 micrograms Hg/d, and 101 +/- 33 micrograms As/d. The dietary As load strongly correlated both with bleeding times and changes in bleeding times (r = 0.48, p < 0.01 and r = 0.54, p < 0.002, respectively). Dietary Hg showed a positive correlation with LDL-cholesterol (r = 0.55, p < 0.01), whereas dietary Hg in the fish group showed a strong negative relationship with HDL-cholesterol (r = -0.76, p < 0.01). Selenium seemed to have only a modest effect on bleeding time. Our results suggest that mercury and arsenic from fish may be factors contributing to or modifying some of the known effects of fish ingestion.