Scientists claim ‘sushi' increases risk of liver cancer

John de Boer (University of Tokyo & GLOCOM Platform)

Once praised in Europe as a mode of reducing the risks of lung cancer and strokes, a recent report in the BBC warns that raw fish could cause liver cancer. This cancer alert is based on the work of scientists now meeting in a UN sponsored workshop on food-born trematodes (in other words worms). These scientists claim that liver cancer and other illnesses will increase in Asia unless more is done to prevent people becoming infected by worms from eating raw fish. According to the World Health Organization there are approximately 40 million people infected by worms, which have been passed on mainly from snails to fish and eventually into humans through consumption. Clare Arthurs, who covered the story for the BBC, reported that repeated infestation can lead to lung disease and liver cancer (26 November 2002). Although most cases are said to be located in Asia, the latest outbreak gaining Europe's attention took place in the Caribbean when 12 tourists from the US caught the meningitis worm after eating unwashed salad in a restaurant ("Tourists catch meningitis worm", BBC, 28 February 2002). The disease was traced back to a slug or snail that came in contact with the lettuce. According to the article, most human cases are associated with eating snails. The crazy thing about all of this is that ‘sushi' and raw fish have been praised throughout Europe as being able to prevent lung cancer. The results of a study conducted at the Cancer Center Hospital in Aichi, Japan have been reported widely throughout Europe in the BBC, the Independent and by nutritionists in Spain as well (see "Sushi could prevent lung cancer", BBC, 2 May 2001). According to this study, "a diet including plenty of raw or fresh fish could protect smokers against lung cancer". Data indicates that both men and women who eat large amounts of fresh fish were significantly less likely to develop lung cancer. Eating raw fish and fish in general has also been linked to a decrease in the rate of strokes. These findings were published in the Journal of the American Medical Association back in January 2001 which described a study that traced nearly 80,000 women over 14 years clearly showing that women who ate more fish had less strokes. In fact, data suggested that people who ate fish five times a week had a 52% reduction in the chance of a stroke ("Eating fish cuts strokes", BBC, 17 January 2001). Based on this information it is difficult to judge what we should do. If we eat raw fish, there is a chance that we could be promoting liver cancer. If we don't we are contributing to the likelihood of liver disease, lung cancer and strokes. According to scientists attending the UN sponsored workshop there is one easy solution. Apparently treatment for food-borne trematodes is simple, we only have to take a pill once a year that costs less than 20 cents US. In that case those who can afford it and have access to it can continue eating raw fish without worry. Nevertheless, with so many "contradictory" findings it's impossible to tell. While the objective of such research should be to make it easier for the average person to understand the risks/benefits associated with eating certain foods, at the end of the day the only apparent outcome seems to be increased confusion.

References:

• Clare Arthurs, "Raw fish cancer alert", BBC, 26 November 2002
• "Tourists catch meningitis worm", BBC, 28 February 2002
• "Sushi could prevent lung cancer", BBC, 2 May 2001
• "Eating fish cuts strokes", BBC, 17 January 2001