Uppdaterat: 2 nov. 2020
Does nutrition play a role in our immune system? Absolutely - and you can help support your immune system though the foods you eat! Even the World Health Organization recently published an article of how nutrition can play a role in our body's ability to prevent, fight and recover from infections. Having a healthy diet can also reduce the likelihood of other health problems such as obesity, heart disease, diabetes and some kind of cancer.
Before we dive in, it is important to understand the immune system is complex and there is usually not one factor that does it all, instead there are several factors that pays a role in the immune system and this is why it is important to look at the whole picture. For the purpose of this blog however I will be focusing on what you can try to do with your nutrition in order to keep your immune system as strong as possible. Even though there are other factors such as sleep, stress and exercise that may also play a role in this. There is still much we don´t know when it comes to nutrition and immunity but we are starting to understand that nutrition matters. Also, it does not matter much if you do it once in a while, what is even more important is what you do most of the time! In other words, you don´t want to just eat well during the fall when everyone is getting sick, you want to eat well majority of the time prior to strengthen your immune system as much as possible and prevent nutrient deficiencies.
PROTEIN: is also called our "building blocks" and the proteins support immune function because the immune cells are different proteins (such as lymphocytes, cytokines, phagocytes etc.). Sources of protein include: meat, chicken, seafood, eggs, beans, lentils, tofu and tempeh.
VITAMIN C: is involved in several important functions in the body including with anti bodies, which is an important protein involved in the immune system. It also helps protect the bodys other cells. Since vitamin C is a water soluble vitamin, it means it cannot be stored and therefore you need it daily in your diet. It is also heat sensitive, therefore it loses some of its nutritional value if you heat it up several times or keep the food heated during a longer period of time. Having too much vitamin C through the diet is not common although taking very high doses through supplements may cause digestive symptoms such as diarrhea and may also cause kidney stones in sensitive people. Also those with heart burn might want to take it easy with too much vitamin C/citrus fruits at once. Sources include: bell peppers, pineapple, cabbage, melon, kiwi, raw leafy greens, berries, tomatoes and other citrus fruits such as oranges, tangerines, grapefruit, lemon and lime.
VITAMIN D: helps maintain the balance of the immune system and your gut. During the winter times and especially if you live in the northern countries such as Sweden. Vitamin D is a fat-soluble vitamin, meaning it can be stored in the body but it is still important to try to include it daily because also everyones need is a bit different (although there usually is one recommended dose for everyone). If you have darker skin you need a bit more compared to someone who has lighter skin. You can absorb vitamin D from the sun, but you will not absorb as much if your skin is covered with clothes. Sources include: fatty fish such as salmon, sardines, mackerel, eggs (with the actual yolk).
ZINC: not having enough or having excess zinc (such as though a high dose supplement) in the body can impact the immune system. Having the right balance help the immune cells and defense mechanisms in the body. Zinc is also one of the minerals that are the toughest for the body to absorb. Animal sources of zinc are better absorbed in the body. If you are a vegetarian/vegan then you need to increase your zinc intake with an additional 25-30 %. Phytate inhibits the absorption of zinc (same as iron) and sources include: meat, pork, lamb, dairy, whole grains, mussels and nuts.
SELENIUM: plays a crucial role in the development and wide variety of physiological processes including effect on immune responses. The immune system relies on adequate dietary selenium. How much selenium foods include depends on the selenium in the soil where plants are grown or what the animals eat. Sources include: seafood, meat, chicken, dairy and Brazil nuts.
IRON: not having enough iron such as iron deficiency can suppress the immune system. From my clinical and private practice experience iron deficiency is one of the most common deficiencies I tend to see, especially among vegans, those who don´t eat enough food, avoid meats, pregnancy and eating disorders. Also, it is the most common deficiency in the world. There are two types of iron, heme and non-heme. Heme iron is easier for the body to absorb and comes from animal sources. Non-heme comes from plant sources and is more difficult for the body to absorb and it is also more influenced by other components. To increase iron absorption you can have it with vitamin C. There are also polyphenols in tea, some herb teas, coffee and wine (doesn't matter if it is alcohol free or not) which inhibits the absorption of iron. Same thing goes with phytates which you find in whole grains, beans, lentils, seeds, nuts which also can inhibit the absorption of iron. Some of the phytates can however be broken down when you consume sour dough bread because of the longer fermentation time. Sprouting the beans, lentils, nuts and seeds can also decrease the amount of phytates which makes it a bit easier to absorb the iron. Consuming too much calcium can also inhibit the absorption of iron, but the research has mainly been done in single meal observations and not longer periods throughout the day. What you can do is to consume calcium and iron two hours apart from each other. The best way is really to include iron rich foods in your diet to prevent iron deficiency because taking an iron supplement may also cause constipation in some people. The is also a risk of iron toxicity from taking too much from supplements, therefore make sure you are in contact with your doctor.
Heme sources: meat (but try to consume lean meats), chicken, turkey, mussels, seafood
Non-heme sources: beans, lentils, dark leafy greens such as spinach or kale, broccoli, dried apricots, peas, tofu, tempeh and soy beans.
VITAMIN A: is important for the skin and lining of the stomach, gut and lungs. This is also where the first line of defense begins against bacteria and viruses. There are two forms of vitamin A: preformed vitamin A called "retinol" which is found in animal foods and provitamin A most commonly known as "carotenoids" which is found in plant-based foods. Carotenoids are dark-colored pigments in plants and can be turned into the active form of vitamin A. One of the carotenoid is called "beta-carotene" which you might have heard of before. Retinol sources include fatty fish, liver, fully fat dairy products and eggs (including the actual yolk). Beta-carotene sources include sweet potatoes, carrots, spinach, mango, papaya, cantaloupe, peaches and apricots.
MAGNESIUM: is involved in several processes in the body (more than 300!), important for the immune system and help support the function of the white blood cells. Sources include: meat, fish, seafood, leafy greens, almonds, nuts, sunflower seeds, whole grains, kidney beans, tofu, cacao and dark chocolate (you might be happy about this one!).
VITAMIN B6: is involved in producing both antibodies and white blood cells which are involved in the immune system. Vitamin B6 is also a water-soluble vitamin so you need it in your daily diet. Sources include: pork, meat, chicken, salmon, banana, hazelnuts, potato with the skin, berries, dairy, oatmeal, beans, lentils and leafy greens.
COPPER: the immune system requires copper to perform several functions but we don´t know the exact mechanism of how it does so. Having too much though a supplement may cause digestive issues and if used during a longer period of time may cause liver damage. This is why it is much better to include it from your diet. Sources include: liver, seafood, nuts, oysters, and cacao. There is also some in meat, fish and whole grains.
B12: having B12 deficiency can suppress the immune system and I have ran across many clients who have had deficiency. If your vegan you need to supplement with B12 because it is found only in animal source foods. Also as we age and the stomach acid decreases it may become more difficult to absorb B12, this is also for those who have been taking antacids for a longer period of time such as Omeprazol. Therefore, include B12 in your daily diet and sources include: eggs (including the actual yolk), liver, meat, chicken, dairy products, enriched plant-based milks such as soy milk or oat milk.
These are the main ones but what you can do starting today is to include these foods in your diet. Next time you go to the grocery store, make a list so you don´t forget these foods because nutrition matters and as more time passes we will realize of how much it actually matters!