Canned soup linked to elevated levels of BPA
Eating canned soup may be convenient, but it can significantly raise the level of bisphenol A in a consumer’s body, according to a new study from the Harvard School of Public Health.
Bisphenol A, better known as BPA, is an odorless, tasteless chemical used in the linings in almost all canned food and drinks, and it is also found in many hard plastic bottles.
Growing evidence suggests that low levels of BPA may be harmful to the development of fetuses and young children.
The Harvard study found that people who consumed a serving of canned soup each day for five days had BPA levels more than 10 times higher in their urine then after they ate fresh soup daily for five days.
“We suspect the increased levels we saw was a temporary increase in BPA, though we can’t say how long it would persist,” said Jenny Carwile, a Harvard doctoral candidate and the study’s lead author.
BPA prevents food and beverage cans from rusting, and increases the shelf-life of canned products. But other studies have found that the chemical can leach from the lining into the contents, regardless of the product’s age or how it is stored.
The Harvard study, published online today in the Journal of the American Medical Association, measured BPA levels in the urine of 75 volunteer students and staff at Harvard, and is one of the first to quantify the levels after people ingested canned food.
One group of volunteers ate a 12-ounce serving of vegetarian canned soup at lunch each day for five days, while another group consumed 12 ounces of vegetarian soup that was prepared without canned ingredients for five days.
After a two-day ‘washout’ period, the groups reversed their assignments. Participants were not restricted in their consumption of any other foods.
Urine samples, taken between 3 p.m. and 6 p.m. on the fourth and fifth day of each phase of the study, found that a serving of canned soup daily was associated with a 1,221 percent increase in BPA compared with levels in urine collected after the volunteers ate freshly-prepared soup.
“A lot of people will say, They ate it at lunch and peed it out so we don’t have to worry about it,” but we don’t know what damage it’s doing in the few hours that it’s there,” said Laura N. Vandenberg, a postdoctoral fellow in Tufts University’s biology department who has done research on BPA, and was not involved in the Harvard study.
Vandenberg said that while the study involved only 75 people, it suggests that large spikes in BPA levels after consuming canned food may not be uncommon.
Another study published earlier this year by researchers at the Silent Spring Institute in Massachusetts found that BPA levels were substantially reduced among five families when canned food and items packaged in plastic were removed from their diets for three days.
The families’ BPA levels returned to their pre-study levels when they resumed their normal diets.
Vandenberg said other studies have found significant variation in the amounts of BPA detected in canned foods made by the same company.
“It varies from one can to the next, and from one food to the next,” she said. “You have no idea if the canned food you are eating is full of it, or not.”
Massachusetts in 2009 warned parents of young children to avoid storing infant formula or breast milk in plastic bottles containing BPA, and also urged pregnant or breast-feeding women to avoid the chemical in other food and drink containers.
But some scientists and advocates say Massachusetts has not gone far enough because studies since then have continued to link health problems to BPA. They have requested that BPA be removed from products typically used by pregnant women and young children. Some states, such as Connecticut, have banned the chemical in infant formula and baby food products, and in a range of reusable food and drink containers.
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