Tag Archives: American Journal of Clinical Nutrition

Fish: Wild or Farmed?

Fish farms

Fish farms (Photo credit: mattroyal)

These days, an increasing number of health-conscious consumers are choosing to eat fish for its heart-healthy benefits. The American Heart Association recommends that adults eat fish twice a week to meet their needs for omega-3 fatty acids, but how do you know if the fish you’re eating is beneficial?

There are many factors to consider when choosing which fish to eat, two of which include species (the type of fish, such as halibut, salmon, etc.) and source (where the fish was raised or caught). These aren’t simple decisions when you consider that the nutritional value of fish varies from species to species, and that each source carries a different potential for contamination, nutrition and environmental impact.

There are millions of fish species, but only a handful are popular for eating and even fewer are considered healthy choices. To choose which species to eat, consider first its fatty acid profile. Fish that live in dark, cold waters naturally contain higher levels of Omega-3’s. The fish richest in omega-3s are cold water fatty fish like salmon, rainbow trout, anchovies, sardines, bass, herring, and tuna.

Next, consider the source. There are two categories of sources of fish: farmed or wild. Each method has its own list of pros and cons, which every consumer will have to weigh to make the best decision for his or her own health and priorities.

Farmed Fish
Fish farming, or aquaculture, means that the fish are raised in floating net pens near the ocean shore. Another name for this method is “ocean raised.”

Pros of Farmed Fish

  • Price: Farmed fish are often cheaper and more readily available than wild fish.
  • Controlled diet: Some farmed fish can have higher levels of Omega-3 fatty acids than wild fish. This is because fish farmers can better control the diets of the fish they raise—making sure that their fish eat more feed that is converted into Omega-3s than a fish might normally eat in the wild. However, there is really no way for consumers to gauge the amount of Omega-3’s in one piece of fish versus another.
  • Ecology: When fish are farmed, there is a lower danger of overfishing (or depleting) the population of wild fish.

Cons of Farmed Fish

  • Contamination: Farmed fish usually contain more contaminants. Farmed fish are fed processed pellets, often made from processed anchovies, sardines and other small fish. Unfortunately, the types of fish used to make the pellets are usually caught in the polluted waters closer to shore and are often contaminated with industrial chemicals. As a result, farmed fish tends to have much higher levels of chemical contaminants that may cause cancer, memory problems, and neurobehavioral changes in children. Farmed salmon, for example, has been found to contain seven times more PCBs (polychlorinated biphenyls), dioxins and pesticides than wild salmon. Consumers can reduce the amount of contaminants in farmed salmon by almost half by grilling or broiling it so that the juices drip off, cooking it until the internal temperature reaches 175 degrees Fahrenheit and removing the skin before eating.
  • Antibiotics: Besides being prone to industrial contamination, farmed fish are more subject to disease, which spreads quickly throughout the entire pen. Sick fish can escape into surrounding open water and spread disease to wild fish populations. To control disease, farmed fish are often given antibiotics to prevent the whole group from becoming ill. Research has shown that farmed salmon, for example, are administered more antibiotics by weight than any other type of livestock.
  • Lower Omega-3’s: While farmed fish can be fed an enhanced diet to increase its Omega-3’s, there is no way for consumers to know whether one piece of fish contains more healthy fats than another. According to research in The American Journal of Clinical Nutritionfarmed salmon contains two or three times fewer Omega-3’s even though it contains more overall fat than wild salmon due to its grain-based diet. The same is is true for other popular farmed fish, such as catfish and tilapia.

Wild-Caught fish
Wild fish, in contrast to farmed, live in open waters and eat a natural diet. Fishermen catch wild fish on open waters, their natural habitat.

Pros of Wild Fish

  • Flavor: Many people prefer the taste of wild fish. Farmed fish do not have as much room to move as their wild counterparts, which reduces the amount of muscle they can develop and affects texture and taste.
  • Appearance: Wild salmon is naturally bright in color due to its food source (krill and other small sea creatures), while farmed salmon is grayish in color and dyes must be added to bring the flesh to an appealing shade.
  • Nutrition: Wild fish are usually healthier (higher in Omega-3s) and less contaminated than farmed fish.

Cons of Wild Fish

  • Overfishing: Most marine biologists agree that there will not be enough wild-captured fish available to meet the growing demand, and many fisheries do not catch wild fish in a sustainable way. Overfishing can deplete certain species of fish, which affects the ecosystem at large.
  • Price: Fresh wild fish is sometimes hard to find and usually more expensive than farmed fish.
  • Distance traveled: Unfortunately, not every fish lover lives on the coast or near a fishery. An Alaskan salmon, for example, must be shipped thousands of miles to reach a grocery store near you. The shipping of fish all over the world uses fossil fuels and pollutes the environment.

Although there are established health advantages to eating fatty fish, the risks of contaminants can’t be ignored either. All fish, wild or farmed, must adhere to FDA limits for PCB content and mercury levels, but some fish may measure in just below that cutoff. This content can build up in the body over time and cause problems later. However, many scientists believe that the heart-healthy benefits of consuming fish outweigh the risk, especially for older adults who may have already had a heart attack. But younger consumers, especially woman who may become pregnant and have a lifetime of exposure to these pollutants ahead of them, may wish to limit the amount of farmed fish they eat.

Only you can decide whether the cardiovascular benefits of fish outweigh the possible safety, nutritional or environmental issues associated with the type of fish you eat. If you eat fish regularly, ask about its source when ordering at a restaurant and read labels for origin when shopping at the supermarket.

No matter what type of fish or seafood you choose, SparkPeople Dietitian Becky Hand offers these top 5 tips for adults* to enjoy healthy fish:

  1. Make seafood a priority. Enjoy fish or seafood at least twice per week.
  2. Be adventurous. Try various types of seafood that you enjoy.
  3. Reel in fatty fish such as salmon and trout. These offer the most health benefits. If you enjoy lean fish such as tilapia and catfish, think about adding another serving of fatty fish to your weekly dinner menu to make up for it.
  4. Don’t skimp on lean fish. They’re healthy, too! Aside from being low in fat and calories, lean fish and shellfish are also loaded with micronutrients that are necessary for good health. For example, tilapia is high in selenium; clams are high in iron; and oysters are high in zinc.
  5. Prepare fish properly. Use low-fat cooking techniques such as broiling, baking, stir-frying, and sautéing. Avoid fried fish and highly processed fish foods such as fish sticks. Season with herbs, spices, marinades and rubs.

*These fish guidelines apply to adults who are not pregnant or breastfeeding. Seafood guidelines are different for children and women who are pregnant or breastfeeding.

Editor’s Note: For more information on a variety of fish, sushi and seafood, including printable pocket-size reference guides, visit: or the Washington State Department of Health.

This article has been reviewed and approved by SparkPeople nutrition expert, Becky Hand, Licensed and Registered Dietitian.


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Magnesium-Rich Food Reduce Stroke Risk

竹叶眉 Bamboo Leaf Vegetable CNY15

A recent analysis of studies showed an 8% reduction in risk for each additional 100mg of magnesium eaten daily.  Possible Connection: The mineral is known to decrease blood pressure, cholesterol levels and the tendency toward diabetes, all of which affect stroke risk.  Foods include: nuts, leafy greens, whole grains, and dried beans.

The researchers found seven published studies over the past 13 years that analyzed the link between magnesium and stroke risk in a total of 241,000 men and women from the US, Europe and Asia. All studies focused on magnesium intake from food. Researchers determined how many milligrams (mg) of magnesium participants consumed from their self-reports of foods they ate each day.

The results: Magnesium was clearly associated with reduced stroke risk. For every 100 mg of magnesium that study participants consumed each day, their risk for an ischemic (blood clot) stroke went down by about 9%. That’s a big drop in risk! And the studies’ risk estimates were adjusted for other factors that might affect stroke incidence—including diabetes, body mass index, physical activity levels, high blood pressure, alcohol consumption, age and smoking—so it really does seem to be the magnesium that does the trick.

How might magnesium contribute to such a significant drop in stroke risk? To help interpret what researchers at the Karolinska Institute in Sweden found in their review, which was published in January 2012 in The American Journal of Clinical Nutrition, I called Roger Bonomo, MD, former director of the Stroke Center at Lenox Hill Hospital in New York City and an expert on stroke prevention.

Dr. Bonomo pointed out that prior research has indicated that magnesium reduces blood pressure and the risk for diabetes—two prominent risk factors for stroke.

What’s interesting is that among Americans studied, the average daily intake of magnesium from food was only 242 mg—that’s less than the 320 mg and 420 mg recommended for women and men, respectively, by the USDA. So even though magnesium appears to be a powerful way to fight off stroke, most Americans aren’t getting enough.

You might be wondering if the subjects in these studies were taking multivitamins that may have contained magnesium. Two of the seven studies adjusted for that, while the others didn’t. In other words, said Dr. Bonomo, taking a multivitamin might provide some magnesium, but it might not be enough. Check the bottle to see how much you’re getting in your multi…but you’ll want to eat magnesium-rich foods as well.


Let’s recap: Consuming an additional 100 mg of magnesium a day may reduce your risk for stroke by 9%. And magnesium isn’t an expensive drug with side effects—it’s a natural mineral that’s already in many of the foods we eat. So what are you waiting for? Most of us, Dr. Bonomo said—especially those of us at high risk for stroke, high blood pressure or diabetes—would benefit from eating more magnesium-rich foods, such as…

  • Pumpkin seeds (191 mg per ¼ cup)
  • Almonds (160 mg per 2 oz.)
  • Spinach (156 mg per cup)
  • Cashews (148 mg per 2 oz.)
  • White beans (134 mg per cup)
  • Artichokes (97 mg per one large artichoke)
  • Brown rice (84 mg per cup)
  • Shrimp (39 mg per 4 oz.)

You can also supercharge your cooking with magnesium if you use oat bran (221 mg per cup) and buckwheat flour (301 mg per cup).

I asked Dr. Bonomo whether anyone should be concerned about overdosing on magnesium. “It’s hard to eat too much magnesium,” he said. “If we do, our kidneys excrete the extra through urine, so only those with kidney failure need to make sure they don’t consume too much.”

Source: Roger Bonomo, MD, neurologist in private practice, stroke specialist and former director, Stroke Center, Lenox Hill Hospital, New York City.




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