Here, Fishy Fishy!
- Intern Foodies
- Oct 9, 2019
- 5 min read
Updated: Oct 10, 2019
Fish in the Sea and the Diet
So far in my series of posts, I have discussed the Mediterranean diet pattern’s inclusion of a plethora of seasonal fruits and vegetables, and its highlight of olive oil as a main ingredient for everyday consumption. Today, I will be diving into the Mediterranean diet’s emphasis on fish along with some potential risks of too frequently eating other forms of protein, like red meat. Fish isn’t completely free of dangers, however. Most fish contain varying levels of mercury, which can be toxic to humans in large doses. This post will tell you all about how to avoid these problems and still receive the benefits of a fish-focused diet.
Surf or Turf?
As I discussed in my first blog post, the Mediterranean diet recommends consumption of fish 2-3 times a week, moderate consumption of poultry products, and rare consumption of red meats. Following this eating pattern can go a long way in supporting health due to the composition of these three animal protein types.
Fish are excellent sources of unsaturated omega-3 fatty acids. These are types of polyunsaturated fat (PUFA) whose fatty acid tails have multiple double bonds in them. The Omega-3 PUFAs are used in many ways throughout the body including in cell membranes, the creation of hormones, and for blood clotting regulation. Omega-3 fats have been shown to have protective effects on the heart and cardiovascular system. They can help lower blood pressure, stabilize heart rate, promote healthy blood vessel function, and in higher doses can lower triglycerides and inflammation throughout the body. A review of findings from scientific studies suggests that eating just 1-2 servings per week of fish high in these omega-3 fatty acids can help to lower one’s risk of dying from heart disease by 36%. Emerging evidence also suggests that eating fish as recommended can also reduce the risk of conditions like depression and Alzheimer’s disease.
Fish also are good sources of Vitamin D and minerals like iodine. Vitamin D can be made in our bodies from sunlight, but still many people are deficient in it as a vitamin that has important hormonal and regulatory roles in the body. Fatty fish like salmon are some of the best natural sources of Vitamin D, with a 4 oz serving having 112% of the average person’s recommended vitamin D intake. Iodine is a mineral crucial to the proper function of the thyroid gland, which uses hormones to regulate many of the body’s organ systems. While iodized salt is an option, using it also increases sodium intake, which can then negatively affect blood pressure. Instead, fish like cod is a great source of iodine for the body that doesn’t require the addition of salt.
Finally, fish is an excellent source of protein, but so are foods such as chicken, beef, and pork. What makes fish a better option? Aside from the health benefits described above, fish is lower in saturated fats when compared to other animal proteins, especially red meats. Saturated fats have been shown to raise blood LDL cholesterol and have negative effects on heart health. Frequent consumption of processed meats like hot dogs, sausages, and beef jerky have even been shown to increase risk for certain cancers. While chicken is often leaner and contains less saturated fat than red meats, it still doesn’t pack the same punch of vitamins, nutrients, and omega-3 fatty acids that fish provides. There are many reasons why making fish the top choice for animal protein is beneficial for overall health outcomes, especially in the case of heart health.
Mind the Mercury!
You may have heard the argument that eating fish is dangerous because the amount of mercury it contains. Mercury is found naturally in the environment, including the air, soil, and water. When its natural occurrence is combined with the factors of water pollution, the mercury in the ocean affects fish more than other animals, especially since the water is the environment animals like fish live and grow in. Throughout their lives fish slowly absorb and store small amounts of mercury in their bodies, that can add up over time. When we eat the flesh of fish we then ingest this mercury.
Since mercury is found naturally in all environments, we humans usually have a bit of mercury in our bodies too, just not enough to cause negative side effects. However, when forms of mercury are consumed in high doses, it acts as a powerful neurotoxin in the body. Possible side effects of mercury poisoning include:
muscle weakness
uncoordinated movements
impairment of walking, hearing, and speech
loss of peripheral vision
“pins and needles” feelings in the feet, hands, and around the mouth
The consequences of mercury poisoning can be worse for infants and children, whose nervous systems are not as resistant to negative effects from mercury. If they are exposed to high doses in the womb or early childhood, this can create long term impairments in their development. Children and pregnant women should still consume fish to get its health benefits, but it is recommended that they only eat the fish that commonly have very low levels of mercury in them. If you have more questions or concerns about your mercury consumption, you can talk to your doctor for more information.
Certain fish consumption advisories may be administered by the government to inform the public of certain fish types or amounts that should be avoided. This can be specific scenarios of avoiding water types that the fish came from or certain sensitive populations like women of childbearing age. Excluding these special situations, fish is usually sorted into 3 categories regarding their mercury concentrations:
Best Choices have the lowest amount of mercury in them and may be consumed 2-3 times per week. This includes fish like salmon, tilapia, canned light tuna, catfish, and sardines.
Good Choices have a slightly higher amount of mercury in them, but are still safe to be consumed once a week. This includes mahi mahi, halibut, and tuna of the yellowfin, albacore, and white varieties.
Choices to Avoid have the highest levels of mercury and shouldn’t be eaten if possible. This includes shark, swordfish, and bigeye tuna.
A final note of importance when choosing fish to purchase is to be mindful of sustainability and the environment. Overfishing is a big issue plaguing our oceans, rivers, and other marine wildlife, and with a diet suggesting that fish be consumed 2-3 times per week, it is crucial to make sure you are purchasing your fish from sustainable and responsible sources. A great resource for consumers is the Monterey Bay Aquarium Seafood Watch Website and mobile app. The Monterey Bay Aquarium has databases available for consumers to search the types of seafood they are buying to ensure their purchasing habits are ocean-friendly. They classify the types and sources of seafood as “best choices”, “good alternatives”, or “avoid”, as is described in the image below. The mobile application is available both on the Apple AppStore and the Google Play store for Android phones.
The staple protein of fish in the Mediterranean diet has been shown to have many positive health effects when consumed a few times every week. However, with regards to fish, not all are treated completely equal. For example, fatty fish are the best sources of Omega-3 fats, and it is important to mainly consume fish lowest in levels of mercury. Overall, fish is an excellent choice and a great contributor to the benefits seen by adhering to the Mediterranean diet. In my next and final post, I will discuss the beverage recommendations of the Mediterranean diet pattern, including a unique inclusion of moderate consumption of red wine. Cheers!
References
Harvard School of Public Health. (2019). Fish: Friend or Foe? Retrieved from: https://www.hsph.harvard.edu/nutritionsource/fish/
Harvard School of Public Health. (2019). Omega-3 Fatty Acids: An Essential Contribution. Retrieved from: https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/
Malesa-Ciecwierz, M. $ Usydus, Z. (2015, January). Vitamin D: Can fish food-based solutions be used for reduction of vitamin D deficiency in Poland? Nutrition, 31(1), 187-192. https://doi.org/10.1016/j.nut.2014.07.003
United States Environmental Protection Agency. (2017). Health Effects of Exposure to Mercury. Retrieved from: https://www.epa.gov/mercury/health-effects-exposures-mercury
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