It’s fall and guess what? Cold and flu season is upon us!

Aside from preventative practices, healthy eating habits can help protect the body from being invaded by harmful bacteria and viruses. This is because the food we eat plays a vital role in helping our immune system function effectively (1, 2).

In this post, I have summarized a few simple tips to help you fight the flu by optimizing your immune system and boosting your body’s immunity.

Eat More Fibre, Less Sugar

There are a few studies that suggest simple sugars may reduce the efficacy of the immune system (3). I’m not going to lie… this association has not been well understood! However, what we know is that fibre intake does reduce inflammation (4, 5, 6). Therefore, you would benefit from substituting foods that are loaded with simple sugars (e.g. baked goods, sweetened dairy, desserts, juice) with high fibre foods (e.g. vegetables, fruits, legumes, and whole-grains).  

Tip: Aim for 25 to 38 grams of dietary fibre by replacing simple carbohydrates with complex carbohydrates, eating beans and lentils as a source of protein, and snacking on fruits, vegetables, and nuts!

Eat More Omega-3 Fatty Acids, Less Omega-6 Fatty Acids

Omega-3 fats are healthy polyunsaturated fats required for optimal body function. There are three types of omega-3 fatty acids: alpha-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The main source of ALA is plant foods such as flax seeds, chia seeds, walnuts, and soy products. DHA and EPA are found in animal foods such as fatty fish (e.g. salmon, herring, mackerel, sardines, trout). 

Omega-3 fats are well known for their anti-inflammatory effects (7, 8). Numerous studies have looked into the molecular mechanisms by which omega-3 fatty acids down-regulate pro-inflammatory genes and reduce inflammatory responses. This is why omega-3 fats are suggested to help those with cardiovascular health problems and other inflammatory conditions.

On the other hand, Omega-6 polyunsaturated fats may act as inflammatory mediators. This, however, is not clear and is subject to further investigation. Note that Omega-6 fats are also healthy and play an important role in promoting overall health. The question is regarding the “optimal” intake levels for Omega-6 fats.

While research is inconclusive, the best recommendation is to ensure a healthy balance between Omega-3 and Omega-6 fat intake (9). The most common source of Omega-6 fatty acids is cooking oils. Like any other food, it’s important that you do not over-consume oils; dietary guidelines recommend that you include more than two to three tablespoons of oils in your daily diet. In addition, you can ensure a healthy Omega-3 to Omega-6 ratio by eating foods that contain Omega-3 fats (9).

Tip: Eat fatty fish at least twice a week! Also, try to boost your Omega-3 fat intake whenever possible!

Omega 3 Fats – how to meet your needs through diet!

Eat More Fruits, Less Juice

To this day when I’m down with the cold or the flu, my mom reminds me to “drink lots of orange juice”! It’s true that orange juice is a good source of vitamin C, but remember that fibre is necessary for a strong immune system. Also, remember that drinking juice introduces the body to a surge of sugar! Hence, a better suggestion would be to eat fruits and vegetables that are a source of vitamin C. A single orange provides your daily vitamin C requirement! Other sources of vitamin C include strawberries, kiwi, sweet peppers and broccoli. So load up on these fruits and vegetables! 

Tip: Snack on fruits and vegetables instead of drinking juice. Drink lots of water (try water infused with citrus fruits)!

Eat More Zinc!

Another key nutrient to help boost immunity is zinc. In fact, zinc is required for the immune systems to function (10, 11)! Zinc is commonly found in seafood (including fish and oysters), beef, legumes (beans and lentils), nuts and seeds. Notice how some of these foods were mentioned earlier? Generally speaking, eating wholesome foods and including more variety in the diet promotes health and wellness! So the message is simple!

Tip: Add beans and lentils to your soup. Snack on seeds, especially pumpkin seeds! 

References

1. Myles, I. A. (2014). Fast food fever: reviewing the impacts of the Western diet on immunity. Nutrition journal, 13(1), 61.
   
2. Rijkers, G. T. (2015). Nutrition, immunity and human health. British Journal of Nutrition, 114(9), 1329-1330.
   
3. Sørensen, L. B., Raben, A., Stender, S., & Astrup, A. (2005). Effect of sucrose on inflammatory markers in overweight humans–. The American journal of clinical nutrition, 82(2), 421-427.
4. Ajani, U. A., Ford, E. S., & Mokdad, A. H. (2004). Dietary fiber and C-reactive protein: findings from national health and nutrition examination survey data. The Journal of nutrition, 134(5), 1181-1185.
5. Fernstrand, A. M., Bury, D., Garssen, J., & Verster, J. C. (2017). Dietary intake of fibers: differential effects in men and women on perceived general health and immune functioning. Food & nutrition research, 61(1), 1297053.
6. Ma, Y., Griffith, J. A., Chasan-Taber, L., Olendzki, B. C., Jackson, E., Stanek III, E. J., … & Ockene, I. S. (2006). Association between dietary fiber and serum C-reactive protein–. The American journal of clinical nutrition, 83(4), 760-766.
7. Calder, P. C. (2009). Fatty acids and immune function: relevance to inflammatory bowel diseases. International reviews of immunology, 28(6), 506-534.
8. Calder, P. C. (2010). Omega-3 fatty acids and inflammatory processes. Nutrients, 2(3), 355-374.
9. Jacob, A. (2013). Balancing Act. Today’s Dietitian, 15 (4), 38.
10. Maggini, S., Maldonado, P., Cardim, P., Fernandez Newball, C., & Sota Latino, E. R. (2017). Vitamins C, D and Zinc: Synergistic Roles in Immune Function and Infections. Vitam Miner, 6(167), 2376-1318.
11. Kaltenberg, J., Plum, L. M., Ober‐Blöbaum, J. L., Hönscheid, A., Rink, L., & Haase, H. (2010). Zinc signals promote IL‐2‐dependent proliferation of T cells. European journal of immunology, 40(5), 1496-1503.