Vitamin C! What is it and what’s it for? Go ahead and take an educated guess… I bet you came up with oranges being a good source of it, and that it can help stave off colds (current research here is actually mixed but let’s be honest, I think many of us, me included, do take it when we start feeling a little bug brewing). Well, you’re right. But here’s some intel you might not have been aware of. Vitamin C is also known as ascorbic acid and is a water soluble vitamin. Under physiologic conditions (normal body conditions), vitamin C exists in its ionized form, ascorbate or ascorbate anion (as it loses a hydrogen). Historically, vitamin C came into the limelight (so pun-ny, limes contain vitamin C, hehe) centuries ago because a deficiency of it results in scurvy. Many mammals can actually synthesize vitamin C on their own, BUT humans cannot (neither can fruit bats so I guess we are in good company, whatever a fruit bat is). The reason we can’t synthesize the vitamin is because we lack an enzyme (gluconolactone oxidase) needed in the pathway that synthesizes vitamin C. Vitamin C is a six carbon compound and a derivative of glucose [1, 2].
The best sources of vitamin C are fruits and vegetables however foods can be fortified, like breakfast cereals for example. Vitamin C is found in its ascorbic acid form in most foods however sometimes it is found in its oxidized form which is referred to as dehydroascorbic acid (it’s missing two protons and two electrons in this form). Vitamin C supplements come in several forms, including free ascorbic acid, calcium ascorbate, sodium ascorbate, and ascorbyl palmitate. Heat, light oxidation and alkaline environments denature the vitamin, whereas it remains stable in acidic solutions. Iron and copper can also oxidatively destroy vitamin C in the GI tract [1, 2].
Vitamin C is required for a number of bodily processes including the synthesis of collagen, carnitine, tyrosine (synthesis and breakdown), and the synthesis of neurotransmitters in that the enzymes that catalyze these anabolic reactions contain mineral cofactors like copper or iron, and vitamin C acts as an antioxidant/reducing agent that keeps these metal atoms in their reduced states so they can continue to function in their enzymatic roles. Vitamin C also functions as an antioxidant in the body. In terms of this role, vitamin C can reduce radicals like hydroxyl, hydroperoxyl, superoxide, alkoxyl, and peroxyl. It can also scavenge hydrogen peroxide, singlet oxygen and hypochlorous acid, and it can reduce some reactive nitrogen species (RNS) as well [1, 2]. This is all good stuff by the way!
And check this out. The highest concentrations of vitamin C in the body are in the adrenal and pituitary glands. High concentrations are also found in the eyes, brain, and in white blood cells. Because of the liver’s total weight, it contains the most vitamin C in the body [1, 3].
In terms of the adrenal glands, vitamin C provides support to them as they produce cortisone and epinephrine. The adrenals also synthesize other hormones that are extremely important, such as sex hormones and cortisol. Cortisol helps the body respond to stress, in addition to serving other functions. The more cortisol the body makes, the more vitamin C that is used in the process. Also, more stress equates to a greater need for vitamin C. The adrenals have vitamin C concentrations 100 times higher than that in the blood. Vitamin C for example is needed as a cofactor for converting dopamine to norepinephrine. During the stress response through hormone regulation, vitamin C is secreted, like in response to stimulation by adrenocorticotrophic hormone (ACTH) for example. So basically, it appears that and increase in secretion of vitamin C is an important part of the body’s stress response, and it also appears that vitamin C requirements are higher in those with higher levels of stress [3, 4, 5, 6].
Regarding the pituitary gland, it acts as a major regulator of other glands because the hormones it releases control these other glands. For example, pituitary hormones affect the thyroid gland, ovaries, testes, and guess which other glands? The adrenals! In particular, the pituitary gland releases andrenocorticotropic hormone (ACTH) which stimulates the adrenal glands to synthesize cortisol during times of stress [6, 7].
So it appears [to me] that vitamin C and these glands (the adrenals and pituitary gland) are related at least in part via the stress response of the body. The pituitary gland releases ACTH in times of stress which stimulates the adrenals to produce cortisol, and this requires the involvement of vitamin C.
And we thought vitamin C was just for colds. Who knew?!?!
- Gropper, S; Smith, J. (2013). Advanced Nutrition and Human Metabolism, Sixth Edition. Wadsworth. p. 307-318