Boosting Flu Season Immunity: 4 Must-Have Nutrients

Dear immune builders, 

In case you haven’t noticed, we’re approaching two monumentous occasions on the calendar year–1) Sweater szn (that’s hip slang for “season,” in case you were wondering), and 2) Flu szn.

Although they present in tandem, you’re probably wondering how you can maximize your time with #1 and totally avoid having anything to do with #2 (and hey, I don’t blame ya–I’m the same way).

If you’ve stepped into like *any* store recently, you probably noticed the display of products, powders, and sprays promising to help you do just that–keep you healthy for the season. While I do believe these products and supplements have their place and may be useful for some, I want to focus on a few ways that you can stay healthy through FOOD this szn (because you know, I’m a dietitian & all). Also synthetic, man-made nutrients (what you’ll find in most supplements) do not always function the same way as the nutrients found in the matrix of food. 

There are a lot of factors involved in building a strong and healthy immune response. However, for the sake of not writing a novel, I’ll highlight the few most important nutrients and tell you how you can easily incorporate them into your daily life (to protect you through sweater szn and BEYOND!)

*Note: I am a Registered Dietitian & the information presented below is backed by research. However, it is not intended to treat/ cure any illnesses, or act as a substitute for individualized medical advice. If you have questions about how this information applies to you personally, please consult your physician and/or Registered Dietitian. 

1. Vitamin C. Woah there, buddy. I know what you’re thinking. “Claire–how obvious. Like, tell me something I don’t know.” Stick with me here.

Vitamin C

The importance of vitamin C to your immune system is well known, however, I see a lot of people choosing to load up on this guy once they’re already sick. Hate to break it to you, but it won’t magically cure your ailments once they’re already upon you. You have to make efforts to include it often!

Vitamin C is an essential, antioxidant vitamin, meaning your body can’t produce it on its own–you have to eat it! It’s also water-soluble, meaning that your body will naturally get rid of any excess that it can’t make use of. This is why taking insane amounts (you know, those supplements that provide like 500% of your daily needs?) will honestly just end up giving you really expensive pee.

For vitamin C to contribute to the strength of your immune system, it’s best to include at least 1-2 food sources of it daily. This way, it can actively play its part before sickness even becomes an issue. Many fruits & veggies contain vitamin C, but some of the most powerful are:

  • Citrus fruits (oranges, grapefruits, lemons, limes, etc.)
  • Other orange & red fruits like cantaloupe, papaya, mango, and strawberries
  • Veggies such as yellow, orange, and red bell peppers, spinach, kale, broccoli, and Brussels sprouts

2. Vitamin E is a fat-soluble antioxidant vitamin. Since it’s fat soluble, it’s stored in the fatty membrane surrounding each of your cells. Interestingly enough, adequate vitamin C intake helps to protect tissue levels of vitamin E and, therefore, indirectly contributes to its immune protecting properties1.

As you age, vitamin E can help to enhance the immediate immune response triggered when you’re exposed to a pathogen, as well as protect your cells from the oxidative damage that can lead to more chronic diseases such as cancer.

Some great food sources of vitamin E include:

  • Almonds
  • Sunflower seeds
  • Hazelnuts
  • Peanuts
  • Salmon
  • Avocados (….I’ll leave my personal opinions on the lil’ green slime balls out of this discussion)
Zinc is the answer
The day Alie & I discovered Zinc was the answer.

3. Zinc’s essentiality for humans was only discovered about 50 years ago! It is a dietary trace element, but it’s also one of the most abundant elements found within the cells in your body.

Zinc is super important for multiple aspects of metabolism and immunity. The mechanisms through which zinc functions in the body are immense and intricate. Generally speaking, though, when it comes to immunity, zinc is crucial to the development of cells that mediate innate immunity (aka the nonspecific defense mechanisms your body has in place to protect you at the first sign of a foreign-invader)2.

Zinc can also function as an antioxidant! (refer to previous vitamin E discussion as to why this is important ^^)

A few food sources of zinc are:

  • Meat
  • Shellfish
  • Legumes & whole grains (not as well absorbed by the body as zinc found in animal products, but still great to include for vegans and/or vegetarians)
  • Nuts & seeds (hemp, pumpkin, sesame)
  • Dairy foods

4. Vitamin D is another fat-soluble vitamin. Your body can only make it after being exposed to sunlight (you can thank your liver & kidneys for that one), but it can also be found in a variety of foods.

Vitamin D is most known for its essentiality in the process of intestinal calcium absorption that promotes proper bone growth and strength. However, research also suggests its importance in the innate immune and antimicrobial response3. AND, as an added bonus, many foods that are naturally high in vitamin D also contain probiotics–the “good bacteria” similar to those found naturally in your gut that also work to protect you from sickness.

healthy food

Some vitamin D containing foods are:

  • Salmon, herring, sardines & tuna
  • Shrimp
  • Egg yolks
  • Milk & cheese
  • Mushrooms (Apart from fortified foods, mushrooms are the only plant source of vitamin D–however, they contain vitamin D2, whereas animal sources contain vitamin D3. Both types of vitamin D are beneficial, but D2 is not as effective as D3. Also, in order to contain vitamin D, mushrooms have to either A) be grown wild, or  B) be exposed to UV light during growth).

Some vitamin D containing foods that also contain live, probiotic cultures are:

  • Kefir 
    • here for a sweater szn-inspired recipe using kefir
  • Yogurt
  • Some types of cheese (look for “active cultures” listed on their food labels)

*Note: If you follow a vegetarian or vegan eating pattern, vitamin D (along with vitamin B12) may be one of the vitamins you choose to supplement–especially in the winter months. 

Questions? Don’t hesitate to reach out here. I’d love to help you implement these suggestions into your life on an individualized level.

Yours Chewly,




P.S. These two aren’t food related, but I’d be doing the topic a disservice if I failed to mention them: SLEEP and STRESS. Lack of sleep and increased levels of stress don’t do your body any favors when it comes to sickness prevention. Strive to keep your sleep schedule sufficient and regular. Also, be sure to engage in as many stress-relieving habits (movement, meditation, socialization, reading, reflecting, journaling, etc.) as you can on a regular basis!

P.S.S. If you’re super serious about preventing spread of the flu and/or you work with higher-risk populations (the elderly, infants, school-age children etc.), then a flu shot may also not be the worst idea. That one’s up to you to decide, but I’m just saying… 


Sources & Additional Readings:

  1. Bendich A. Vitamin E and immune functions. Current neurology and neuroscience reports. Accessed October 1, 2018.
  2. Prasad AS. Current neurology and neuroscience reports. Published 2008. Accessed October 1, 2018.
  3. Aranow C. Current neurology and neuroscience reports. Published August 2011. Accessed October 1, 2018.



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