Omega-3, vitamin D and the immune system

What we eat plays an important role in our health and well being. Many of the nutrients we get from food are essential, meaning that the body cannot produce these nutrients itself, and must get them through the food we eat. This requires a good and well balanced diet. The marine omega-3 fatty acids EPA and DHA are examples of essential fatty acids. Vitamin D is also a nutrient we need to get through our diet if we do not get enough sunlight. Sufficient Vitamin D is essential for our immune system to function normally, and Omega-3 has been shown to play a role in the acquired immune system.

Vitamin D - the sunlight vitamin

Vitamin D is special because the body can produce this vitamin through the skin if the skin is exposed to sunlight. Nevertheless, studies show that a lot of people suffer from vitamin D deficiency[1-4], especially in northern regions and during wintertime when there are shorter days of sunlight. People with dark skin or people with clothing covering most of the skin are also particularly prone to vitamin D deficiency.

Due to this, it is especially important to ensure adequate intake of vitamin D through the diet during the darkest winter months. Unfortunately, other than fat fish, roe and egg yolk, there are few good sources of vitamin D in our diet. Some types of margarine, butter and milk are fortified with vitamin D.

A lot of people know that Vitamin D is important for bone health, but few know that Vitamin D is essential for the immune system to function normally[5]. Vitamin D seems to be especially important for the innate immune system, which is the body's first line defense against bacteria and viruses. The innate immune system is nonspecific and is activated quickly after initial contact with the infectious agent. Low levels of vitamin D have been associated with an increased number of infections, including upper respiratory tract infections and influenza[6]. Studies also show that the number of infections was significantly reduced when supplementing with vitamin D[6].


Omega-3 is a collective term for long-chained unsaturated fatty acids, and includes, among others, ALA, EPA and DHA. ALA is an omega-3 fatty acid found in vegetable sources such as avocado, walnuts and vegetable oils. ALA does not have many biological functions other than being an energy source and is therefore a poor source of omega-3. EPA and DHA, on the other hand, have many essential functions. These fatty acids are important constituents of cell membranes and produce signaling molecules that can reduce inflammation[7]. Studies have also shown that supplementation of fish oil could make B-cells, a type of white blood cell and part of the acquired immune system, more responsive to inflammatory stimuli and secrete more antibodies[8, 9]. This could mean that fish oil can improve the acquired immune system.

As with vitamin D, many people consume inadequate amounts of omega-3 through their diet[10]. Generally, EPA and DHA are only found in marine sources such as fish and seafood. Fatty fish and cod liver are especially rich in these fatty acids. Because a lot of  people do not eat adequate amounts of fish and seafood in everyday life, it could be necessary to use a supplement of fish oil. Smartfish's products contain good amounts of EPA and DHA from fish oil, and meet the daily needs. In addition, Smartfish's products are fortified with vitamin D to ensure the intake of this important vitamin.

  1. Hypponen, E. and C. Power, Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors. Am J Clin Nutr, 2007. 85(3): p. 860-8.
  2. Visser, M., et al., Low serum concentrations of 25-hydroxyvitamin D in older persons and the risk of nursing home admission. Am J Clin Nutr, 2006. 84(3): p. 616-22; quiz 671-2.
  3. Ginde, A.A., J.M. Mansbach, and C.A.C. Jr, Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med., 2009. 169(4): p. 384-390.
  4. Thomas, M.K., et al., Hypovitaminosis D in medical inpatients. N Engl J Med, 1998. 338(12): p. 777-83.
  5. EFSA Panel on Dietetic Products, N.a.A.N., Scientific Opinion on the substantiation of health claims related to vitamin D and normal function of the immune system and inflammatory response (ID 154, 159), maintenance of normal muscle function (ID 155) and maintenance of normal cardiovascular function (ID 159) pursuant to Article 13(1) of Regulation (EC) No 1924/2006, E.F.S.A. (EFSA), Editor. 2010: EFSA Journal.
  6. Gunville, C.F., P.M. Mourani, and A.A. Ginde, The Role of Vitamin D in Prevention and Treatment of Infection. Inflammation Allergy Drug Targets, 2013. 12(4): p. 239-245.
  7. Siriwardhana, N., N.S. Kalupahana, and N. Moustaid-Moussa, Health benefits of n-3 polyunsaturated fatty acids: eicosapentaenoic acid and docosahexaenoic acid. Advances in food and nutrition research, 2012. 65: p. 211-222.
  8. Rockett, B.D., et al., n-3 PUFA improves fatty acid composition, prevents palmitate-induced apoptosis, and differentially modifies B-cell cytokine secretion in vitro and ex vivo. Journal of Lipid Research, 2010. 51: p. 1284-1297.
  1. Gurzell, E.A., et al., DHA-enriched fish oil targets B cell lipidmicrodomains and enhances ex vivo andin vivo B cell function. J Leukoc Biol., 2013. 93(4): p. 463-470.
  2. Papanikolaou, Y., et al., U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003-2008. Nutrition journal, 2014. 13: p. 31-31.