The relationship of serum ferritin with sex and exercise in Canadians of Icelandic descent: implications for prevention of coronary artery disease.

OBJECTIVE

To investigate the relationship of serum ferritin with sex and exercise.

DESIGN AND SETTING

A cross-sectional design study carried out in Winnipeg, Manitoba.

SUBJECTS

Urban Canadians of Icelandic descent, aged 21 to 60 years, took part in this investigation. Subjects were stratified by age, sex and menstrual status.

INTERVENTIONS

Venous blood samples from fasting subjects were drawn for serum ferritin, hemoglobin and hematocrit analyses. Various anthropomorphic measurements were taken, and subjects underwent submaximal cycle ergometry testing. A health and lifestyles questionnaire and a four-day prospective food record were administered.

MAIN RESULTS

Mean serum ferritin levels obtained were 187.93 and 47.84 micrograms/L for males and females, respectively. Mean serum ferritin levels were 33.06 micrograms/L and 71.14 micrograms/L for premenopausal and postmenopausal females, respectively. The mean weekly consumption of alcohol was 190 mL/week and 80 mL/week for males and females, respectively. The mean dietary intake of iron was 27.3 and 18.9 mg/day for males and females, respectively. Males, but not females, who exercised 45 mins or more per week had significantly lower levels of serum ferritin than their sedentary counterparts. In males, hemoglobin, hematocrit and the consumption of alcohol were positively correlated with serum ferritin, while exercise time was negatively correlated with serum ferritin. A trend towards lower serum ferritin levels at higher workloads was observed in males, but did not reach statistical significance. In females, age and dietary intake of iron were found to be positively correlated with serum ferritin, while history of anemia, menstrual status and workload were negatively correlated with serum ferritin.

CONCLUSIONS

These findings suggest that regular aerobic exercise may decrease iron stores in the body. This may be clinically significant since high serum ferritin has been cited as a risk factor for coronary artery disease.