Vitamin C [Nutrient feature!]

Can you guess what all of these foods have in common?


They are all excellent sources of vitamin C.



Here's something fascinating that I recently learned about vitamin C. The number one storage site for vitamin C in the body is ... the adrenal glands. Your body needs vitamin C to make norepinephrine, an essential hormone and neurotransmitter that's important for your 'fight or flight' response. If you're constantly stressed, this depletes the levels of vitamin C in your adrenal cortex and could compromise your adrenal function.


Unlike most mammals and other animals, humans do not have the ability to synthesise vitamin C and must obtain it from the diet. If you use it and you don't keep eating it, you lose it. And if you lose it, that's a problem. Your body relies on vitamin C to complete many vital functions because vitamin C acts as a cofactor for a number of enzymes that make important things happen in the body. For example, if you don't have vitamin C, your body can't:


  • Make collagen. You need collagen to maintain connective tissue, heal injuries to tissue, and remodel bone.

  • Make carnitine. Important for using fatty acids for energy.

  • Protect immune cells called neutrophils. If you're exposed to bacteria or a virus, neutrophils defend your body and release chemicals to neutralise the threat. In this process, neutrophils soak up vitamin C so that the neutrophil itself doesn't self-destruct in the firing line.


How much vitamin C do you need each day?


This one's a little complicated. Most of the time, the RDA (USA) and RDI (AU) match. But for vitamin C, they don't.

  • The RDA in the US is 75 mg for an adult female and 90 mg for an adult male.

  • The RDI is Australia is set at just 45 mg for both females and males.

However, if you dig a little deeper you'll see that in Australia there's also a 'Suggested Dietary Target' set for vitamin C at 190 mg for women and 220 mg for men.* You won't find this in an app like Cronometer though, so remember to factor it into your calculations. We also know that an upper intake level of 2 g/day (that's g, not mg) is sufficient to prevent susceptible adults from experiencing related digestive troubles.


Based on this, I aim for > 200 mg daily. I'd rather be on the optimal end of the scale than on the average side.**


What are some excellent food sources of vitamin C?


Most people think vitamin C = oranges. I'm a big fan of oranges, but there's other fantastic foods that you can add to your day to bump up your vitamin C.


Here's a list of some of my favourite foods in order of vitamin C content based on NCCDB data. I've used realistic portion sizes so that you can easily put this into practice and be able to tally your daily intake.

  • Red capsicum. The surprise winner. 1 cup of red capsicum contains 117 mg of vitamin C.

  • Pineapple. 1 cup of pineapple contains 79 mg.

  • Oranges. 1 medium orange contains about 70 mg.

  • Kiwi fruit. Just 1 kiwi fruit contains 64 mg.

  • Parsley. Half a cup of fresh parsley contains 40 mg. (Tip: It's easy to consume that if you chop it finely and toss it in a salad.)

  • Tomato. 1 large tomato contains 25 mg.

  • Lemon. The juice from one lemon contains 18 mg.

All up, this plate contains about 320 mg of vitamin C. That's 3.5 x the RDI.



A tip for preparing your foods to maximise vitamin C content


If you can, eat these foods fresh and either raw or lightly cooked. Vitamin C is sensitive to light, air and heat. If you're cooking a food that contains vitamin C you'll still access some of it (for example, broccoli or brussel sprouts), just keep in mind that it loses about 25 % of its vitamin C content due to cooking.


Notes


* An SDT is set for nutrients if there is a reasonable body of evidence of a potential preventive effect in relation to chronic disease at levels substantially higher than the RDI.


** There's also evidence that 200 mg is the upper limits for maximal bioavailability. After that, bioavailability starts to decrease an the body excretes a lot more vitamin C.


Sources