Smoking out cadmium problem

Multivariate analysis of AAS data help home in on the problem of decreased fruit and vegetable consumption being associated with elevated blood cadmium concentrations in smokers.

Hyesook Kim, Hee Jung Lee, Ji-Yun Hwang, and Namsoo Chang, Eun-Hee Ha, and Hyesook Park of the Ewha Woman's University, Seoul, Mina Ha of Dankook University College of Medicine, Cheonan, Korea, Ja Hyeong Kim of Ulsan University Hospital, and Yun-Chul Hong of Seoul National University College of Medicine, Korea, have investigated the benefits or otherwise of fruit consumption in male smokers.

"Decreased fruit and vegetable consumption, along with elevated blood cadmium concentrations, are frequently observed among cigarette smokers," the team says. They point out, however, that few studies have looked into whether or not there is an association between blood cadmium concentrations in cigarette smokers and what amount of dietary antioxidative nutrients they consume.

Excess exposure to trace metals, such as zinc and copper, despite, being essential nutrients can be detrimental to health. However, cadmium is a non-essential metal and produces only significant adverse health effects. In assessing the impact of this element one must consider total and accumulating exposure and the absorption route and rate, whether it was inhaled or ingested. Cigarette smoking represents a fast and efficient route for absorbing this toxic heavy metal. Cigarettes contain cadmium at concentrations ranging from 1.56 to 1.96 micrograms per cigarette.

"Cadmium is one of several chemicals in cigarette smoke that generate reactive oxygen species and thus places smokers at a greater risk of free radicals. As a result, smokers may have a greater need for antioxidant nutrients and phytochemicals," the team explains.

It is possible that vitamin C and fibre may together help to reduce blood cadmium concentrations by decreasing the intestinal absorption of the metal. Fibre seems to have an inhibitory effect on its gastrointestinal absorption by forming insoluble complexes with phytates in the intestine. Vitamin C while being an antioxidant that might ameliorate the effects of oxidising free radicals produced by the presence of cadmium, might also enhance iron absorption and so inhibit cadmium absorption.

The Korean researchers have now used graphite furnace atomic absorption spectrophotometry to determine blood cadmium concentrations in whole blood samples from 546 adult men. The pregnant wives of the men were registered in the Mothers and Children's Environmental Health Study and so were a useful cohort for other unrelated studies. They looked at dietary intake of antioxidants and phytochemicals and assessed those using a semi-quantitative food frequency questionnaire (FFQ). The FFQ is the most commonly used dietary assessment tool for large epidemiological studies of diet and health. Participants report on the frequency of consumption and portion size of approximately 120 different food stuffs over a defined time period.

The team explains that, as anticipated, the concentration of cadmium in the blood of smokers was higher than in non-smokers. They carried out multiple regression analysis with covariates to reveal that blood cadmium levels were negatively associated with the intake of fruit, vitamin C (ascorbic acid), and dietary fibre, but only in the smokers.

This, the researchers say, is the first report that blood cadmium concentrations in cigarette smokers are inversely associated with the consumption of fruit. "One notable feature of our study is that we estimated intakes of fruits and vegetables using a semi-quantitative FFQ, which reflects long-term food consumption," they conclude.