(Updated with the latest science on December 30, 2021; Originally posted April 14, 2020)
Now, more than ever, people are looking for ways to “boost” or support their immune systems. An important step in staying healthy is eating a balanced diet of fruits, vegetables, whole grains, legumes, seafood and fatty fish, lean meats, low-fat dairy products, and nuts and seeds.
“Nutrients, the things we eat, are a very important part of how our immune system functions in addition to things like physical activity and not smoking,” said Dr. Philip Calder, professor of nutritional immunology at the University of Southampton and author of a recent peer-reviewed study, “Nutrition and immunity: lessons for COVID-19.” “The immune system is central to protection against infection. In the past 18 months, weak immune systems have been exposed as a major public health challenge.”
Good nutrition is essential to supporting a strong immune system, and if there is one food that packs a punch of a wide spectrum of vitamins and minerals, it is seafood. “Seafood is an excellent source of immune-supporting micronutrients, some of which, like Vitamin D, are really hard to get from other foods,” said Calder at the Seafood Nutrition Partnership’s 2021 State of the Science Symposium.
Data from the NIH-AARP Diet and Health Study of more than 420,000 people show eating seafood reduced respiratory deaths by 20 percent. In fact, higher fish and omega-3 fatty acid intakes were significantly associated with lower total mortality.
Seafood, both fish and shellfish, provides essential nutrients to the body that keep the immune health functioning properly. Seafood is a nutrient-packed food that reduces inflammation with vitamins A, B, and D, as well as omega-3 fatty acids and minerals such as calcium, selenium, phosphorus, iron, zinc, iodine, magnesium, and potassium (2,4).
Good nutrition is essential to supporting a strong immune system, which may offer protection from many health problems including chronic disease. The Dietary Guidelines recommend regular fish and seafood consumption for optimal wellness of all functions of the body (12). Data from the NIH-AARP Diet and Health Study of more than 420,000 people show eating seafood reduced respiratory deaths by 20% (1). In fact, higher fish and omega-3 fatty acid intakes were significantly associated with lower total mortality.
Here are some key nutrients found in a variety of seafood that works together in keeping your immune system functioning properly.
Omega-3s EPA and DHA – Omega-3s EPA and DHA found in seafood “are very important to the immune system,” Calder said. “They are also anti-inflammatory, which means they can reverse the harmful effects of the immune response. This is a really important effect in the context of immunity.” Different species of seafood offer different amounts of omega-3 fatty acids. Fish with the highest omega-3 levels include salmon, herring, anchovies, oysters, sardines, and trout. Here is a chart of seafood options that shows levels of omega-3 fatty acids.
B Vitamins – B vitamins such as B2, B6, and B12 all help keep the immune system working properly by regulating inflammation while promoting red and white blood cell development to keep the oxygen flowing while fighting against disease (4,7). Seafood, both fish and shellfish have a variety of B-vitamins.
Vitamin D – “Vitamin D controls the function of the immune system,” Calder said. D plays an important part in the innate antimicrobial (an agent that kills microorganisms) response, which helps keep the immune system functioning properly (2,8). “Perhaps the most important dietary source is fatty fish.” Seafood options that have a good source of vitamin D include sardines, salmon, herring, and tuna.
Iron – Iron is essential in the activation and reproduction of immune cells. All shellfish are high in iron, but clams, oysters, and mussels are particularly good sources.
Selenium – Selenium, which is often overlooked according to Calder, has a role in mitigating viral mutation. It is an antioxidant that helps to lower oxidative stress levels in the body, which in turn reduces inflammation and enhances immunity (10). All seafood has selenium; tuna, sardines, clams, halibut, and shrimp are all good options to consider.
Zinc – Zinc helps the immune system work properly and may help wounds heal. It’s found in cells throughout the body (2,4). It helps the immune system fight off invading bacteria and viruses. The body also needs zinc to make proteins and DNA, the genetic material in all cells. Shellfish like oysters, crab, and lobster are good sources of zinc. Zinc is found in fish like sardines, salmon, flounder, and sole.
Protein- Protein plays a role in the body’s immune system, especially for healing and recovery (2). Seafood contains a high-quality protein that includes all of the essential amino acids for human health, making it a complete protein source.
Vitamin A – Vitamin A helps regulate the immune system and protect against infections by keeping skin and tissues in the respiratory system healthy. It also is known as an anti-inflammation vitamin because of its critical role in enhancing immune function. Oily fish like salmon, king mackerel, cod, tuna are good sources of vitamin A.
Iodine – Iodine is the fuel that powers all metabolic activity in the body. Since the immune system relies on the proper functioning of the metabolism to stay healthy, iodine is useful in making sure your immune response is active (6). Iodine is found in a good quantity of seafood like cod, scallops, lobster, seabass, and shrimp.
Magnesium – Magnesium aids in regulating immune cell development (9). Fish like salmon, mackerel, and halibut all contain magnesium.
Potassium and calcium – Potassium indirectly controls calcium and immune cell signaling (11). Sardines, salmon, and shrimp all have sources of calcium whereas fish with good sources of potassium include halibut, tuna, cod, and snapper.
No one food or supplement can prevent illness, but the immune system can be supported by including these key nutrients found in seafood on a regular basis.
The Consensus: How to Support the Immune System
Try to stay healthy overall and keep the immune system functioning at its best. Everyone can benefit from eating the recommended amount of seafood – which is two or more servings per week according to the Dietary Guidelines for Americans to add up to 1,750mg of omega-3s EPA+DHA per week (12).
Seafood is a great option to include on your weekly menu because it pairs well with other food groups. Try eating a balanced diet of fruits, vegetables, whole grains, legumes, seafood and fatty fish, lean meats, low-fat dairy products, and nuts and seeds. All of these foods have a variety of key nutrients that contribute to immune health. If one isn’t getting an adequate amount of these foods in their diet daily, be sure to consult a doctor to see whether a supplement would be beneficial.
Other lifestyle habits important to health and supporting the immune system are exercise, getting adequate sleep, managing stress, and not smoking.
A Deeper Dive Into the Science
For a deeper dive into the science of immune health, here is a video of Dr. Calder’s presentation at the 2021 State of the Science Symposium.
- Zhang, Y. et al. Association of fish and long-chain omega-3 fatty acids intakes with total and cause-specific mortality: prospective analysis of 421 309 individuals. J Intern Med. 2018 Oct;284(4):399-417. doi: 10.1111/joim.12786.https://www.ncbi.nlm.nih.gov/pubmed/30019399
- Childs C. et al. Diet and Immune Function. Nutrients. 2019 Aug; 11(8): 1933. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723551/
- Lee GY. et al. The Role of Vitamin E in Immunity. Nutrients. 2018 Nov 1;10(11). pii: E1614. doi: 10.3390/nu10111614. https://www.ncbi.nlm.nih.gov/pubmed/30388871/
- Maggini S. et al. Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients. 2018 Oct 17;10(10). pii: E1531. doi: 10.3390/nu10101531.https://www.ncbi.nlm.nih.gov/pubmed/30336639
- US Department of Agriculture, Food Data Central at fdc.nal.usda.gov https://fdc.nal.usda.gov/fdc-app.html#/food-details/174202/nutrients
- U.S Department of Health and Human Services. National Institutes of Health. Office of Dietary Supplements: Iodine. https://ods.od.nih.gov/factsheets/Iodine-Consumer/
- U.S Department of Health and Human Services. National Institutes of Health. Office of Dietary Supplements: B12 https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
- Aranow, C. Vitamin D and the Immune System. J Investig Med. 2011 Aug; 59(6): 881–886. doi: 10.231/JIM.0b013e31821b8755. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
- Schmitz, C. et al. Magnesium and the Immune Response. Science Direct. Molecular, Genetic, and Nutritional Aspects of Major and Trace Minerals 2017, Pages 319-331. https://www.sciencedirect.com/science/article/pii/B9780128021682000269
- Avery, J. et al. Selenium, Selenoproteins, and Immunity. Nutrients. 2018 Sep; 10(9): 1203. Published online 2018 Sep 1. doi: 10.3390/nu10091203https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163284/
- Feske, S. et al. Ion Channels in Innate and Adaptive Immunity. Annu Rev Immunol. Author manuscript; available in PMC 2016 Apr 6. Published in final edited form as: Annu Rev Immunol. 2015; 33: 291–353. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4822408/
- U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. https://www.dietaryguidelines.gov/