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Vitamin C plays a key role in keeping our immune system strong. Our immune systems are often likened to little armies, with “branches” and “soldiers” playing various roles in protecting us. That analogy is actually pretty good as we all have many different systems and cells in place that all play a different role when fighting off any sort of invader such as bacteria or viruses. And like real armies, some battles are easier to win than others. Bacteria can arguably be less complicated to deal with, as our body’s innate and adaptive immune system can often more readily locate them and attempt to deal with them. And, if they run into problems, antibiotics can usually provide help in eradicating the unwelcome guests. Viruses on the other hand, can be much more difficult to deal with, both for our immune systems and from a clinical perspective. 

When a virus infects us, it quickly attempts to hide inside our own cells in order to survive and replicate. To complicate matters for our immune systems, viruses, being highly adaptable, have developed ways to avoid being found while hiding out. And while our immune systems do have multiple cells and systems on board to discover cells with viruses hiding out in them, they are only successful if all these systems are working properly.

Vitamin C deficiency, the fourth most common nutrient deficiency in the US, can result in impairment of these mechanisms and cause you to be more susceptible to infections while making it more difficult for your immune system to fight off invaders once you are infected. With a large number of folks in the US deficient in this key nutrient, it’s no wonder they turn to high supplemental doses of vitamin C when they get sick, in an effort to ramp up their sluggish immune systems when they are needed most.

The reality is, rather than waiting until you are sick to pound the vitamin C, it may be much more effective to regularly maintain optimal levels of vitamin C through your diet. By regularly maintaining optimal levels, not only could you be more likely to ward off microbial invaders before they’re able to set up camp, but your immune system will be better prepared to fight if necessary.

The current RDA in the US for vitamin C is dependent on age and gender (as well as if you’re pregnant/lactating or a smoker) with 90mg/day recommended for adult males and 75mg/day for non-pregnant females. Unfortunately, this amount isn’t quite enough to reach optimal plasma levels. Ideally, your dietary intake should be between 100-200mg/day. Studies show that most individuals with low levels of vitamin C (plasma ascorbate levels under 23 μmol/L) are able to reach optimal plasma levels in one to two weeks with this amount.

Vitamin C Foods

The best part is that as long as you’re eating a colorful array of fruits and veggies, it’s incredibly easy to meet this level each day. These are our top 10 Paleo-friendly foods that have more than enough vitamin C on board to help you reach optimal levels, and maintain them, in no time. Your immune system, and all its “soldiers” will thank you!

+ 1/2 large yellow bell pepper 171mg

+ 1 medium red bell pepper 152mg

+ 1 large orange 98mg

+ 8 large strawberries 85mg

+ 1 large kiwi 85mg

+ 1 cup chopped broccoli 81mg

+ 1 cup chopped kale 80mg

+ 1 cup brussels sprouts 75mg

+ 1 cup chopped red cabbage 51mg

+ 20 small clams 42mg

Bonus foods!

While you aren’t going to eat large amounts of these foods, ounce for ounce, they all pack a pretty sizable amount of vitamin C. It’s definitely worth working them into your daily diet whenever you can.

Orange and lemon peels – Freeze and grate into smoothies, salad dressings, or teas. Ounce for ounce, they pack twice as much vitamin C as the fruit!

Chives – An excellent addition to eggs, salads, soups, or just about any veggie dish. Especially useful for folks with FODMAP issues that want that onion taste, but need to avoid onions.

Parsley – Extremely versatile, add it to salads, smoothies, roasted veggies, soups, salad dressings, or stews. For a real treat (and vitamin C bump), try Alton Brown’s Parsley Salad recipe.

Leeks – With a milder flavor than the typical onion, you can use leeks anywhere you would their stronger flavored counterparts.



Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017;9(11):1211. Published 2017 Nov 3. doi:10.3390/nu9111211

Carr AC, Pullar JM, Bozonet SM, Vissers MC. Marginal Ascorbate Status (Hypovitaminosis C) Results in an Attenuated Response to Vitamin C Supplementation. Nutrients. 2016;8(6):341. Published 2016 Jun 3. doi:10.3390/nu8060341

Patrone F, Dallegri F. [Vitamin C and phagocytic system: present status and perspectives (author’s transl)]. Acta Vitaminol Enzymol. 1979;1(1-6):5-10.