A consortium of nutrition experts has urged pregnant American women to increase their consumption of fish above US government levels recommended three years ago.

In 2004 the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) advised that pregnant and nursing mothers, and young children, should limit their consumption of fish low in mercury to 12 ounces (approximately two portions) a week.

They also advised them not to eat certain fish at all: shark, swordfish, king mackerel, or tilefish, because they contained high levels of mercury (as methyl mercury). The agencies also advised these groups to limit their consumption of albacore tuna to 6 ounces, or one portion, per week.

However, this advice is now being challenged by a group of experts in maternal nutrition who said yesterday that pregnant women should consume a minimum of 12 ounces of seafood a week but within this to limit albacore tuna to 6 ounces a week.

The new advice has increased the heat in the debate about what is safe for pregnant women to eat.

The main area of concern is mercury, a toxic metal that finds its way into seafood in a compound called methyl mercury. Mercury affects the development of the brain in fetuses and young children.

The problem with fish consumption is around “bioaccumulation”. Because mercury stays in the organism, those fish at the top of the food chain, the predators, will gradually accumulate higher levels of the toxin as they eat more and more fish lower down the food chain.

The confusion that is arising appears to be in the detail: different types of seafood are likely to accumulate different levels of mercury, and also different types of seafood differ in health giving properties such as levels of omega-3 fatty acids. So it’s a question of balancing benefits against risks and knowing what these are.

The Maternal Nutrition Group and the National Healthy Mothers, Healthy Babies group are of the view that pregnant, breast-feeding mothers can safely eat a minimum of 12 ounces of seafood a week but within that to limit the amount of albacore tuna to 6 ounces because this type of fish is a predator at the top of the food chain.

The consortium is concerned that mothers don’t stop eating fish and lose a vital source of omega-3 fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid which are necessary for healthy development of the brain and nervous system in fetuses and newborns. They also said that there is a lot of research evidence that fatty acids also help visual, motor, cognitive and behavioural development in the early years.

It would seem that the effect of the FDA and EPA recommendation has lodged in people’s minds as a general message that fish is bad for you because of the potential for mercury poisoning. But perhaps what women need to do is learn about the nutritional benefits of different types of fish and which ones are likely to have higher levels of mercury and decide for themselves.

However, this is only possible with good, reliable, information.

One potential source of information that may be useful here is Co-op America’s “Safe Seafood Tip Sheet”. This purports to be the only source that “looks at both the health and environmental issues surrounding your fish choices”.

The producers of the Tip Sheet say they drew on the “best data on environmental sustainability from the Monterey Bay Aquarium” and also examined the Environmental Working Group’s information about toxins, and took into account the information from the FDA, EPA and other agencies.

They suggested, for example that Anchovies, Calamari, Clams, Crawfish, Herring, King crab, Lobster (spiny/rock), Mid-Atlantic blue crab, Perch, Sardines, Sole, Tilapia, and Whitefish, among others, are safe to eat.

Not recommended, they said, for various reasons either to do with environmental unsustainability or toxicity are Monkfish, Sea bass, Shark, Swordfish, Halibut, Atlantic Cod, Farmed Catfish, and others.

They also suggested certain seafood should be limited to one serving a month, including lake trout, pollock, wild catfish, non-Atlantic cod, Blue mussel.

Click here for Co-op America’s “Safe Seafood Tip Sheet” (PDF download).

Written by: Catharine Paddock