Fish is an essential component of a healthy diet, offering a wealth of nutrients vital for overall well-being. Rich in omega-3 fatty acids, vitamin D, selenium, and high-quality protein, while remaining low in saturated fat, fish provides numerous health advantages. However, it’s crucial to understand the potential risks associated with consuming fish, such as exposure to contaminants like mercury and microplastics, as well as environmental and ethical concerns related to overfishing. This article delves into the benefits and risks of incorporating fish into your diet, providing guidance on making informed choices for your health and the planet.
Health Benefits of Eating Fish
Cardiovascular Health
Strong evidence suggests that including fish in your diet, or supplementing with fish oil, can significantly benefit your heart and blood vessels. Studies indicate that consuming approximately one to two 3-ounce servings of fatty fish per week-such as salmon, herring, mackerel, anchovies, or sardines-can reduce the risk of dying from heart disease by as much as 36 percent.
The omega-3 fats present in fish play a crucial role in protecting the heart against erratic cardiac rhythm disturbances, lowering blood pressure and heart rate, improving blood vessel function, and reducing triglycerides and inflammation at higher doses. These benefits are so compelling that organizations like the Dietary Guidelines for Americans and the American Heart Association recommend that everyone consume fish twice a week.
Potential Reduction in Risk of Other Chronic Conditions
Eating fish once or twice a week may also reduce the risk of stroke, depression, Alzheimer’s disease, and other chronic conditions.
Nutritional Value
Seafood is a concentrated source of many essential nutrients. It is the primary dietary source of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are involved in many aspects of health, including nerve cell function and the regulation of inflammation. Diets high in seafood significantly benefit the health of the nervous and cardiovascular systems, mainly due to the content of EPA and DHA in seafood.
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Seafood is highly nutritious, providing a source of healthy fats, protein, vitamins, and minerals. Eating seafood has been linked to a lower risk of many health conditions, including coronary heart disease (CHD), depression, and liver cancer.
Benefits of a Pescatarian Diet
A pescatarian diet, which is a primarily vegetarian diet with the addition of fish and other seafood, may offer potential health benefits. Eating a diet consisting mainly of plant-based foods has a variety of health benefits, which the addition of fish and fish products may enhance.
People who follow a pescatarian diet have a lower risk of cancer than meat eaters. Following a pescatarian diet also had a specific reduction in risk for colorectal cancers - those affecting the colon and rectum.
Studies show that following a plant-based diet may help reduce the risk of type 2 diabetes and metabolic syndrome. The omega-3 fats found in fish have powerful anti-inflammatory effects and may benefit health in many ways when consumed in large doses.
Potential Risks and Considerations
Contaminants in Fish
Numerous pollutants, including mercury, polychlorinated biphenyls (PCBs), dioxins, and pesticide residues, can find their way into the foods we eat, including fish. Very high levels of mercury can damage nerves in adults and disrupt the development of the brain and nervous system in a fetus or young child. While the effects of lower levels of mercury found in fish are controversial, they have been linked to subtle changes in nervous system development and a possible increased risk of cardiovascular disease.
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However, it's important to put these risks into perspective. An analysis by Harvard School of Public Health professors Dariush Mozaffarian and Eric Rimm suggests that the benefits of eating fish outweigh the risks. They calculated that if 100,000 people ate farmed salmon twice a week for 70 years, the extra PCB intake could potentially cause 24 extra deaths from cancer-but would prevent at least 7,000 deaths from heart disease. Furthermore, levels of PCBs and dioxins in fish are very low, similar to levels in meats, dairy products, and eggs.
At the levels commonly consumed from fish, there is also limited and conflicting evidence for effects of mercury in adults. The Environmental Protection Agency, the Food and Drug Administration, the Institutes of Medicine report, and the analysis by Mozaffarian and Rimm all conclude that this evidence is insufficient to recommend limitations on fish intake in adults, given the established benefits of fish consumption for cardiovascular disease.
Mercury Levels and Pregnancy
High intake of mercury appears to hamper a baby’s brain development. However, low intake of omega-3 fats from fish is at least as dangerous. Women should recognize that avoiding seafood altogether is likely to harm their babies’ brain development. The healthiest approach for women who are or may become pregnant, nursing mothers, and young children is to eat two servings per week of fish or other seafood, including up to one serving per week of white (albacore) canned tuna, and avoid the four fish species higher in mercury (shark, swordfish, tilefish, king mackerel).
Fried and Salted Fish
Frying seafood leads to unfavorable changes, including the creation of harmful compounds called heterocyclic amines (HCAs), acrolein, aldehydes, and polycyclic aromatic hydrocarbons, which are known to contribute to the development of diseases like cancer. Eating fried fish frequently is associated with an elevated risk of certain cancers, including lung and prostate cancer. Intake of salted and smoked fish has also been associated with significantly increased disease risk.
Microplastic in Seafood
Human activity has caused a buildup of microplastic in the marine environment. Researchers warn that ingesting seafood containing microplastic likely harms health, though research in this area is limited.
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Environmental and Ethical Issues
The demand for seafood has led to overfishing and has destroyed marine environments worldwide. Experts fear that the poor fishing management, irresponsible methods used to procure seafood, and the rampant overfishing that occurs worldwide will lead to a collapse of fisheries and a global food crisis. Prioritizing sustainable fishing and fish farming practices is critical to protect existing marine environments.
Commercial fishing vessels often use irresponsible methods of fishing, such as trawling, which not only destroys the delicate habitats on the ocean floor, but can lead to massive amounts of non-targeted species, like turtles and sharks, being caught as bycatch.
Making Informed Choices
Fish to Include in Your Diet
A person on a pescatarian diet can eat canned sardines, canned salmon, canned tuna, fish sticks, frozen salmon, trout, and herring, frozen shrimp, fresh fish, such as cod, salmon, pollock, catfish, and sardines, fresh shellfish, such as shrimp, clams, and scallops.
Other foods to include are fruit, vegetables, cereals and whole grains, including oats, bulgar wheat, amaranth, corn, and rice, pseudo grains, such as quinoa and buckwheat, which are gluten-free, legumes, including kidney beans, pinto beans, and peas, legume products, including tofu and hummus, nuts and nut butters, seeds, such as flaxseeds, hemp seeds, and chia, eggs and dairy, if lacto-ovo-vegetarian.
Recommendations for Specific Populations
Except perhaps for a few fish species, the scale tips in favor of fish consumption for women who are pregnant. In a study of almost 12,000 pregnant women, children born to those who ate less than two servings of fish a week didn’t do as well on tests of intelligence, behavior, and development as children born to mothers who ate fish at least twice a week.
The healthiest approach for women who are or may become pregnant, nursing mothers, and young children is to eat two servings per week of fish or other seafood, including up to one serving per week of white (albacore) canned tuna, and avoid the four fish species higher in mercury (shark, swordfish, tilefish, king mackerel). It is important that women recognize that the list of fish and seafood that they should eat is far larger than the few specific species to be avoided. Eat up to 12 ounces (two average meals) a week of a variety of fish and shellfish that are lower in mercury.
Sustainable Seafood Choices
Prioritizing sustainable fishing and fish farming practices is critical to protect existing marine environments. You can help by reducing your overall consumption of seafood, purchasing only sustainably caught seafood, and avoiding eating species that are overfished.
Choose fish that’s fished or farmed in environmentally sustainable ways. Clams as well as Arctic char from Canada caught by barriers and fences are among the best choices, and there are many more sustainable options. Use the Monterey Bay Aquarium Seafood Watch online search tool to learn which fish are considered the worst choice for sustainability.
Preparing Fish Healthily
Instead of breading and deep-frying or pan-frying seafood, try baking, sauteing, or steaming seafood. Pair seafood with other nutritious foods, such as vegetables, beans, and whole grains.
Other Considerations
- Check local advisories: Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas.
- Be mindful of omega-3 sources: Not all omega-3 fats come from fish. Americans also consume plant omega-3s in the form of alpha-linolenic acid (ALA), which is found in flax seeds, walnuts, and a few vegetable oils.
The Mediterranean Diet
If you're looking for a heart-healthy eating plan, the Mediterranean diet might be right for you. The foundation of the Mediterranean diet is plant foods. Moderate amounts of dairy, poultry and eggs are part of the Mediterranean diet, as is seafood. Unsaturated fats are a strength of the Mediterranean diet. Olive oil and nuts are the main sources of fat in the Mediterranean diet.
Fish also are a key part of the Mediterranean diet. These are known as fatty fish. Omega-3s are unsaturated fats that may lower immune system action in the body known as inflammation. Lean fish and shellfish also are included in the Mediterranean diet. Shellfish include shrimp, crab, clams and scallops.
Potential Disadvantages of a Pescatarian Diet
Depending on your current diet, going pescatarian may represent a shift from how you’re used to eating. And if you’re unsure how to cook fish, you may find the transition tough. Luckily, fish and shellfish are relatively simple to prepare.
Also, be mindful of how you're preparing your fish. Broiling, grilling, baking, poaching, steaming, and sautéing are preferable to frying. Additionally, if you are worried about mercury consumption from fish, the current recommendation is at least two servings of fish per week.
One caveat: If you're pregnant, pay particular attention to your choices and aim to consume no more than 8 to 12 oz of fish per week. The nutrients in fish support healthy fetal growth, and experts recommend consuming two to three servings of lower-mercury fish per week. Ideally, these will come from fish with the lowest levels of mercury, which includes crab, shrimp, tilapia, salmon, sardines, and cod. Children are also encouraged to eat two servings per week of these fish.
Concerns with Farm-Raised Fish
One of the biggest concerns with farm-raised fish is its potential to contain industrial chemicals, including terephthalic acid (TPA) and polyvinyl chloride (PVC). Fish raised in farms may also contain chemicals used to "improve" their coloring (e.g. the salmon you buy that appears ultra-pink), which could have an impact on our health. And then there's the question of the antibiotics.
Farmed fish are generally "grown" as monocultures - or a single species of fish. Most farmed fish are grown in nets that are overcrowded, which can pose problems. The population can become infested with sea lice, or other microbes, due to their congested living conditions. They recommend eating farmed salmon, for example, no more than once or twice a month.
Plastic Contamination
Recent studies have shown that the so-called Pacific Garbage Patch in the north Pacific Ocean is more than twice the size of France, containing a giant mass of marine debris, including hundreds of millions of pieces of plastic. Wild fish have been found with plastic in their digestive systems, and many of the chemicals in plastic get absorbed into their fat.