Researchers presented Tuesday the strongest evidence yet for eating fish, with a study showing it reduces blood pressure, cholesterol and one key blood fat even better than a healthful vegetarian diet.
This is the first time scientists have studied two populations that are almost identical except for their diets. Italian researchers studied more than 1,200 people in two East African villages that are only 40 miles apart.
Finding such a group was important because scientists didn’t have to account for any other differences, such as smoking, alcohol or culture.
“To evaluate people eating fish with other people is very difficult because there are so many other differences,” said Santica Marcovina, a research professor of medicine at the University of Washington in Seattle. “The Japanese, for example, are very lean. Americans, in general, aren’t.”
Both of the villages in Tanzania are populated by ethnic Bantus. One village is on the shore of a large lake, and residents eat as much as a pound of fish, Marcovina said. The other village, separated from the lake by mountains, is populated by farmers who have no livestock and eat vegetarian diets heavy in rice and maize.
The two groups’ lifestyles are very similar and both take in about 2,000 calories a day.
In addition to having slightly lower blood pressure and cholesterol levels, the group that ate fish had 40 percent lower levels of a specific heart-threatening fat.
Scientists at a conference in Orlando said Tuesday that finding is particularly significant because that blood fat has been linked to only genetic factors. The study is the first to show the substance, which is related to the harmful cholesterol LDL, can be strongly influenced by diet.
Marcovina said there probably are no genetic differences between the two villages because intermarriage is common.