Global shift in farmed fish feed may impact nutritional benefits ascribed to seafood

The fish-farming industry is increasing its use of plant-based ingredients in its feed and moving away from traditional feed made from fish, which could impact some of the health benefits of eating certain types of seafood, suggests a new analysis from the Johns Hopkins Center for a Livable Future (CLF) at the Johns Hopkins Bloomberg School of Public Health.

The findings are published March 11 in the journal Environment International.

Half of the seafood consumed by Americans is farmed. Fish farming, also known as aquaculture, is the fastest-growing food animal sector, outpacing the beef and poultry industries. While wild fish find their own food -- which includes smaller fish for carnivorous species -- intensively farmed fish are fed a manufactured aquaculture feed. Until recently, this manufactured feed was typically composed of high levels of fishmeal and fish oil derived from wild fish -- but it has become unsustainable to catch more wild fish to feed growing numbers of farmed fish, so the industry has shifted the makeup of the feed. For example, twice as much soybean meal was used in commercial aquaculture feed in 2008 as compared to fishmeal, and the use of crop-based ingredients is projected to increase 124 percent between 2008 and 2020.

"Farmed fish get their health-promoting omega-3 fatty acids, EPA and DHA, from their feed, and specifically from fish oil," says study leader Jillian Fry, PhD, director of CLF's Public Health and Sustainable Aquaculture Project and a faculty member at the Bloomberg School. "Our review found that increasing plant-based ingredients can change the fatty acid content in farmed fish, which can affect human nutrition."

The new study details the industry shift to crop-based feed ingredients, such as soy, corn, and wheat, to replace wild fish as a key ingredient in manufactured feed. The researchers -- in collaboration with colleagues from the University of Minnesota's Institute on the Environment and McGill University -- reviewed aquaculture and public health literature, and conducted a new analysis to estimate the environmental footprint for the top five crops used in commercial aquaculture feed.

The shift has been hailed by some as a positive change in light of the increasingly depleted oceans and the rapidly expanding aquaculture industry. But the shift may have some unintended consequences as well.

Using vegetable oils instead of fish oil changes the fatty acid content of fish and nutritional value for human consumption, the researchers say. Considering Americans are encouraged to consume seafood high in omega-3 fatty acids, which promote improved cardiovascular health and neurodevelopment, this has large implications for dietary recommendations and the aquaculture industry. More research is needed, they say, to better understand the impact of this shift in feed on the health benefits of consuming farmed fish.

While fish-based ingredients are seen as acutely limited, so are the resources such as land, water and fertilizer used to produce feed crops. Aquaculture's environmental footprint likely now includes increased nutrient and pesticide runoff from the industrial crop production needed to supply fish food. This runoff is a key driver of water pollution globally, and can negatively impact public health. Depending on where and how feed crops are produced, plant-based fish feed could be indirectly linked to negative health outcomes for agricultural workers and nearby communities due to exposure to air, water or soil contaminated by nutrients and/or pesticides.

Fry says that these new findings may raise more questions than they answer.

"The nutritional content of farmed fish should be monitored," Fry says. "The aquaculture industry should assess the environmental footprint and public health impacts of their crop-based feed ingredients and seek those produced using sustainable methods."

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The above post is reprinted from materials provided by Johns Hopkins University Bloomberg School of Public Health. Note: Materials may be edited for content and length.

Time to rethink your vegetable oil?

Risk of heart disease and diabetes may be lowered by a diet higher in a lipid found in grapeseed and other oils, but not in olive oil, a new study suggests.

Researchers at The Ohio State University found that men and women with higher linoleic acid levels tended to have less heart-threatening fat nestled between their vital organs, more lean body mass and less inflammation.

And higher linoleic acid levels also meant lower likelihood of insulin resistance, a precursor to diabetes.

This finding could have obvious implications in preventing heart disease and diabetes, but also could be important for older adults because higher lean body mass can contribute to a longer life with more independence, said Ohio State's Martha Belury, a professor of human nutrition who led the research.

But there's a catch. Low-cost cooking oils rich in linoleic acid have been disappearing from grocery shelves, fueled by industry's push for plants that have been modified to produce oils higher in oleic acid.

"Vegetable oils have changed. They're no longer high in linoleic acid," said Belury, an expert in dietary fats and part of Ohio State's Food Innovation Center.

The research appears online in the journal Molecular Nutrition & Food Research.

The research team also looked at the health effects of oleic acid, found in olive oil and some other vegetable oils, as well as long-chain omega-3 fatty acids, found in fatty fish including salmon and tuna.

Though inflammation decreased as blood levels of those fatty acids rose, higher levels of oleic acid or long-chain omega-3s did not appear to have any relationship to body composition or signs of decreased diabetes risk despite longstanding recommendations that people eat more of these "healthy" fats.

"It really kind of popped out and surprised us," Belury said.

Previous research found that taking linoleic acid supplements increased lean body mass and lowered fat in the midsection. As little as a teaspoon and a half was all it took, Belury said. The current study is the first study to examine linoleic acid alongside body composition and other health markers in people who hadn't been given supplements or prescriptive diets, she said.

Because of previous research showing cardiovascular benefits of linoleic acid, the American Heart Association in 2009 recommended people take in at least 5 to 10 percent of their energy in the form of omega-6 fatty acids, which includes linoleic acid.

But U.S. consumption of linoleic acid is declining because of genetic modification of plants for food manufacturers seeking oils higher in oleic acid, Belury said.

There's been a pronounced shift in the last five years, she said, and it is linked to the push against trans fats. When linoleic acid is made solid (hydrogenated) for processed foods, it is more likely to convert to trans fat than its oleic cousin.

So oils, notably safflower, sunflower and soybean, now routinely contain less linoleic acid -- it often makes up less than 20 percent of the fatty acids in commonly purchased oils, based on food labels and confirmed by testing in her lab, Belury said.

Grapeseed oil for now remains an excellent source of linoleic acid, which constitutes about 80 percent of its fatty acids, she said. Corn oil also remains a decent source, she said.

The team used data from two previous studies that focused on stress and included 139 people. In those studies, researchers assessed body composition using DXA scanning, an advanced way of measuring fat and muscle mass.

They tested blood drawn after the men and women fasted for 12 hours, calculating the amount of linoleic acid (and other fatty acids) in red blood cells. All of the linoleic acid in our bodies comes from food sources.

They also evaluated the blood for insulin resistance and two markers of inflammation that are connected with disease.

Then they plotted results for each health category against the group's results for each of the three fat categories: linoleic acid, oleic acid and long-chain omega-3 fatty acids.

Belury said the study doesn't explain the apparent interplay between linoleic acid and measures of risk for heart disease and diabetes. It shows an association between those things, but not a cause and effect. And its power is limited because it relied on looking back on two previous research efforts and those involved middle-aged men and women who were slightly healthier on average than the general population.

The study participants lived in and around Columbus, Ohio. It's possible that the results would have been different in a population with diets that tend to be higher in omega-3 rich fatty fish, Belury said.

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The above post is reprinted from materials provided by Ohio State University. The original item was written by Misti Crane. Note: Materials may be edited for content and length.

Fuel or food? Study sees increasing competition for land, water resources

As strategies for energy security, investment opportunities and energy policies prompt ever-growing production and consumption of biofuels like bioethanol and biodiesel, land and water that could otherwise be used for food production increasingly are used to produce crops for fuel.

About 4 percent of the world's agricultural land and 3 to 4 percent of its fresh water are now used for growing biofuels, according to a new study published March 3, 2016 in the Nature journal Scientific Reports. About one-third of the malnourished people in the world, the findings suggest, could be fed by using these resources for food production.

With the world's population at about 7.4 billion people, and projected to grow to about 9 billion by the middle of the century, the need for food and fuel could increasingly be at odds.

"We are investigating and evaluating the affects of biofuels on food security -- the food-energy nexus -- and its link with the global appropriation of land and water," said Paolo D'Odorico, an environmental sciences professor at the University of Virginia who co-wrote the paper with colleagues in Italy. "The land and water resources claimed by biofuel production have been poorly quantified, and we are trying to gain better understanding to help inform public policy."

D'Odorico said that if biofuel production for transportation were to be increased to 10 percent of the total fuel used by the transportation sector -- as is projected to occur based on recent policy and business patterns that encourage renewable energy production -- the planet could meet the food needs of only about 6.7 billion people.

"We are looking at a food deficit for about 700 million people with respect to our current world population," D'Odorico said. "It will only get worse as the population grows."

The research team based its analysis on biofuel consumption rates inferred from data by the United Nation's Food and Agriculture Organization and other sources. They estimated the water and land footprints of one unit of biofuel energy and reconstructed global trade patterns for bioenergy crops. They determined that the approximately 4 percent of agricultural land and water used for producing biofuels would be sufficient to feed about 280 million more people if used for food crops.

"These results clearly show the extent to which biofuels are competing with food for the limited land and water resources of the planet, and are becoming an additional obstacle to bringing food production in line with the increasing needs of the human population," D'Odorico said.

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The above post is reprinted from materials provided by University of Virginia. Note: Materials may be edited for content and length.