In a change of course, the US now wants pregnant women to eat more fish, but not the kinds that are high in mercury.
Altering its 2004 advice to shun most seafood, the United States Food and Drug Administration (FDA) said in an updated report that pregnant and breast-feeding women and young children should eat fish that was low in mercury levels to gain important health benefits.
Those fish, including salmon, trout, anchovies and sardines, are high in essential omega-3 fatty acids. The FDA also noted that pollock, shrimp, tilapia, catfish, cod and canned light tuna were safe to consume while pregnant or breast-feeding.
For the first time, the agency set a minimum amount of fish needed in the diets of pregnant and breast-feeding women and young children. The agency said women should consume at least 225 grams and up to 340 grams, or two to three servings, of a variety of seafood each week. Previously, it put a cap on the amount of fish pregnant women and children should eat, but not a base level.
The updated advice aligns recommendations for pregnant women and young children with those in its 2010 dietary guidelines for Americans.
"Seafood can be a great source of protein, iron and zinc, crucial nutrients for your baby's growth and development," wrote Dr Roger Harms, a pregnancy specialist at the Mayo Clinic.
"In addition, the omega-3 fatty acids in many fish can promote your baby's brain development."
The updated draft still leaves much to be desired for consumer groups, such as the Mercury Policy Project, which was disappointed with the failure of authorities to require labelling and address exposure risks from Americans' heavy consumption of canned tuna.
"Over one-third of Americans' exposure to methlymercury is from tuna, because tuna are higher-mercury fish and Americans consume so much," Michael Bender, director of the Mercury Policy Protect group said.
"Albacore 'white' canned tuna generally has three times as much mercury as 'light' tuna. However, Americans consume about three times as much of the light variety.
"Therefore, each variety, white and light, contributes a staggering 16 per cent of Americans' dietary exposure."
New labelling procedures were not included in the updated guidelines.
The guidelines also recommend limiting consumption of white tuna to 170 grams a week. "If you regularly eat fish high in mercury, the substance can accumulate in your bloodstream over time," an official warned.
Red meat linked to breast cancer
Women who often indulge their cravings for hamburgers, steaks and other red meat may have a slightly higher risk of breast cancer, a new study suggests.
Doctors have long warned that a diet loaded with red meat is linked to cancers including those of the colon and pancreas, but there has been less evidence for its role in breast cancer.
In the study, paid for by the US National Institutes of Health, Harvard University researchers analysed data from more than 88,000 women aged 26 to 45 who had filled in surveys in 1991. While some never ate red meat or did so less than once a month, others ate six or more servings a day. The research, published online on Tuesday in the British journal BMJ, confirmed follow-up findings published in 2006.
Using a statistical model, scientists estimated that in women who ate the most red meat, there were an extra 6.8 cases of breast cancer for every 1,000 women over 20 years. The researchers could not rule out the possibility that other factors might explain the apparent link between red meat and breast cancer. In developed countries, women have about a 12.5 per cent chance of developing breast cancer. Scientists suspect proteins in red meat speed up cell division and tumour growth.
The study was carried out mainly among educated, white American women, and researchers said that the results were not necessarily applicable to women of other races.