Schools offer lessons for hardy first-timers who want to experience sled dog travel.
Subscribe to one of our news e-mail lists . A new study raises the disturbing possibility that taking vitamin C pills may speed up hardening of the arteries. Researchers called their discovery a surprise and cautioned that more experiments are needed to know for sure whether megadoses of the vitamin actually are harmful. Still, they said the finding supports the recommendations of health organizations, which generally urge people to avoid high doses of supplements and to get their nutrients from food instead. Many people load up on vitamin C and other nutrients on the assumption that these supplements are good for their health, even though there is little scientific evidence this is true.