People who take supplements containing glucosamine and chondroitin to protect their joints are also reducing their chances of developing colon and lung cancer. American researchers working on the VITAL study made the discovery. They have been closely following 77,000 men and women aged between 50 and 76 since about 2000.
The VITAL study is intended to find out whether supplements do enhance health, as the industry claims, or in fact damage health, as a growing group of scientists says. So far there have been very few epidemiological studies specifically directed at the health effects of supplements.
When the researchers recruited participants they asked them about their supplement intake over the previous 10 years. They then monitored their subjects for 5 years. In that period 665 of them developed lung cancer. From looking at the subjects' supplement use and whether it was in any way related, the researchers compiled the table below.
The black band shows the statistically significant relationships. Glucosamine and chondroitin takers had 25% less chance of developing lung cancer than non-users.
Of the group of subjects that the researchers monitored, 426 men and women got bowel cancer. Garlic pills increased the chance of developing colon cancer. St John's wort and MSM reduced the chance considerably, followed by fish oil and, once again, glucosamine and chondroitin.
Glucosamine and chondroitin inhibit catabolic mechanisms that are triggered by Interleukine-1. Interleukine-1 plays a role in cancer. Fish oil inhibits inflammation; MSM boosts the immune system; and how St John's wort works – the researchers have no idea. Nor do they know the exact quantities of supplements that the participants took.
The results from the same project also showed that glucosamine and chondroitin reduced mortality.