When it comes to fish, you are what you eat

It is well known that eating fish is good for your health. Dr Anne Williams of the University of Otago tells Charmian Smith about the benefits – and some of the downsides – of eating fish.

Fish and chips may be one of the most popular ways to eat fish in New Zealand, but it’s not necessarily the healthiest because of the frying, says Dr Anne Williams of the Department of Nutrition from the University of Otago.

Originally from the United States, she has a background in fisheries science and nutrition and thinks of fish consumption from a global perspective. She is also the director of the World Health Organization (WHO) Collaborating Center for Human Nutrition in Otago.

However, appointed to the university at the start of the pandemic, she has not yet been able to come to Dunedin and works from Atlanta, Georgia. Now that the borders have opened up, she plans to move here in time to teach in person from the second semester.

“If we talk very broadly, fish is a good source of long-chain fatty acids, the polyunsaturated fatty acids that are important for membranes and our nerve endings and a lot of cell signaling,” she said. .

Most people know that there are good fats (mono and polyunsaturated) and bad fats (saturated and trans) and that fish in general contains good fats, especially omega 3 and omega 6 long chain fatty acids. .

Fish is also a great source of lean protein, she says.

While here we mainly eat filleted fish (except for white bait and shellfish), in many traditional societies they eat small whole fish or parts of larger fish which we generally discard, such as nutrient-rich fish heads and livers.

While working with native communities in Alaska, she first encountered people who liked to eat fish eyeballs. It made her think about what a unique source of vitamin A they were, she said.

When she was working in western Kenya around Lake Victoria, she discovered that the larger fish were sent to fancy restaurants or exported, but the locals ate omena, small fish the size of our white baits .

“If you eat small fish, you’re consuming their intestines and skeletal structure. What’s important in these organ systems is that you get a lot of micronutrients. In food-insecure populations, there’s often micronutrient deficiencies,” she said.

“These little fish are cheap, they’re tasty, they’re used in much of the local cuisine, which includes fish stews. It’s one of the most nutrient-dense foods available to locals. They are a very important source of proteins, fats and multiple micronutrients that are often missing from the diet.”

Many of the health benefits of eating fish (contributing to heart, brain and eye health and helping to prevent depression) come from the long-chain polyunsaturated fatty acids as well as micronutrients, but it all depends on how you cook it from, she said.

You can quickly reduce the health benefits if you eat your fish fried — as in fish and chips — rather than steamed or in a stew.

Canned fish has similar nutritional value to cooked fish.

“Whenever I have a choice between fish and other meats, I go for fish,” she said.

She prefers not to talk about the advantages of wild fish over farmed fish due to the politics and economics around fish farming, but a lot depended on what they were fed, says Dr Williams.

You are what you eat and that’s true whether you buy pastured eggs from the supermarket, grass-fed dairy, or wild or farmed fish, she explains.

But there are downsides to eating fish, and it’s worth choosing your fish carefully, she says.

With wild fish there is always the question of sustainability and overfishing, if a species is endangered and how it is caught.

New Zealand has a quota management system that has both supporters and detractors, and Dr Williams cites the example of the International Pacific Halibut Commission she has worked with. It has a reputation for being one of the best managed fisheries in the world, she says.

Halibut is a large flatfish caught off the Pacific coast of North America, but almost 100 years ago fishermen realized the population was in decline and called for monitoring. A treaty between the United States and Canada established the commission which still manages the fishery, assesses fish stocks and undertakes research.

In general, wild-caught fish have been shown to have a lower carbon footprint than lamb or beef, despite the fuel used in the boats to catch the fish and the processing costs. However, if imported, the fish also incurs the additional carbon cost of transport.

Then there’s the issue of environmental toxins such as methylmercury, a highly toxic compound in the oceans that can build up in fish, especially larger, longer-lived species.

Pregnant and breastfeeding women and young children are more vulnerable to potential heavy metal toxicity, although they also benefit from the micronutrient density and favorable fatty and amino acids, Dr. Williams says.

“If you’re concerned about environmental toxins, you’d be interested in eating lower down the food chain. Heavy metals and pollutants have had less opportunity to amplify in smaller fish that are eaten by larger fish. and fish that have longer lifespans that are large and old and have the potential to acquire more and more toxins over their lifetime.”

A more recently recognized concern is the problem of microplastics in the ocean that fish eat or absorb – but that’s another story.

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