The versatile vitamin’s mechanisms of action
This article serves as Part 3 in our series on vitamin C, pain, and opioid use disorder. Check out Part 1 to learn about the vitamin’s use in the management of pain. In Part 2 we dive into its potential for easing opioid withdrawal symptoms and drug cravings.
Vitamin C (ascorbic acid, AA) is an essential nutrient in humans, meaning we cannot make the vitamin in our bodies and therefore need to consume it in our diets or from nutritional supplements. While most people know of vitamin C as an important nutrient for immune support, few people are aware of the vitamin’s role in the treatment of addictions.
Specifically, vitamin C may help those with opioid use disorder (OUD, or “opioid addiction”) have fewer drug cravings and less intense symptoms of withdrawal when they either reduce their dosage of opioids or stop using them altogether. This is great news, especially when we consider that drug overdose is the leading cause of death among Americans under the age of 50,1 and that opioids — drugs like oxycodone, hydrocodone, morphine, heroin, codeine, and fentanyl — are implicated in overdose deaths more than any other drug class, ending more lives than guns, breast cancer, or car accidents.2 In short: OUD is the deadliest drug crisis in American history.3,4
Opioid use disorder is the deadliest drug crisis in American history
That’s in large part because it is incredibly difficult to overcome OUD. For the person with OUD, any significant reduction in their daily drug regimen can lead to debilitating cravings and at times horrifically unpleasant symptoms of withdrawal – symptoms like severe pain, abdominal cramping, diarrhea, nausea and vomiting, sweating, agitation, insomnia, and elevated blood pressure and heart rate.5 In fact, the term “quitting cold turkey” comes from a description of the goose bumps that can form on a person’s skin as they go through withdrawal, giving the skin an appearance similar to that of uncooked poultry.
There are a number of mechanisms by which vitamin C may help people with OUD reclaim their lives and their sobriety:
Vitamin C supports both the immune system and mental health through its antioxidant activity. By scavenging a variety of reactive oxygen species (ROS), vitamin C protects our cells (including those of the central nervous system) against oxidative damage.6,7
A shockingly high number of psychiatric disorders – including anxiety,8,9 depression,10–12 bipolar disorder,13,14 panic disorder,15,16 obsessive-compulsive disorder (OCD),17 and schizophrenia – are associated with excess oxidative stress.18,19 Antioxidants are therefore crucial for mental health.20–22
A study of 137 individuals addicted to heroin revealed that this population experiences a high rate of oxidative injury as compared to healthy controls.23 Another study found that the longer a person had been using heroin, the more oxidative stress their body was under – and the injury to the cells was correlated with low levels of vitamin C and other antioxidants.24
The longer a person had been using heroin, the more oxidative stress their body was under.
Fortunately, numerous animal studies show that vitamin C can battle oxidative stress and reduce depression.25,26 Vitamin C has also been shown in multiple randomized, double-blind, placebo-controlled trials in human subjects to help not only with opioid addiction, but also with depression and anxiety.27–29 (People with mental health conditions like anxiety and depression are three times more likely to use opioids than the general population.3)
Vitamin C also preserves glutathione, A.K.A. “the master antioxidant” in our red blood cells and liver cells.
Opioid medications deplete glutathione levels in the body, thus enabling a vicious cycle of worsening pain, which requires more opioid usage, which further depletes glutathione levels, and thus in turn perpetuates pain.30,31
Just 500 mg of vitamin C supplemented daily was shown in one clinical trial to increase mean red blood cell glutathione levels by almost 50% after just two weeks.32 Vitamin C and glutathione have also been shown to completely reverse opiate-induced liver damage in rats.33
Oxidative stress and inflammation are birds of a feather: where you find one, the other is soon to follow. Inflammatory markers like C-reactive protein (CRP) are often elevated in those with depression and other mood disorders.34–37 Conventional pharmaceutical antidepressants (SSRIs, etc.) work in part by their anti-inflammatory and antioxidant effects,39,40 further illuminating the role of inflammation on mood.
Fortunately, vitamin C has been shown to dramatically decrease various markers of inflammation, including CRP, tumor necrosis factor (TNF), interferon, and interleukins.38
Vitamin C supplementation may thus support the body’s synthesis of important neurotransmitters.
Tetrahydrobiopterin (also known as THB or BH4) is required for the biosynthesis of several neurotransmitters, including serotonin, melatonin, dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). Vitamin C supports brain chemistry by recycling THB.41,42
Vitamin C is also necessary for the body’s conversion of dopamine into norepinephrine. Perhaps unsurprisingly, animals deficient in vitamin C have been found to also have low levels of norepinephrine.43–45
Vitamin C has also been shown in rats to modulate the actions of dopamine and glutamate, an excitatory neurotransmitter. This is yet another mechanism by which vitamin C may dampen tolerance and withdrawal,46,47 as both the glutamatergic and dopaminergic systems are involved in opiate addiction.48
The adrenal glands, which sit atop each kidney, are central to our response to both physical and emotional stress. The cortex, or “crust” of these glands produces not only the stress hormone cortisol, but also vitamin C as part of the normal stress response.49 Vitamin C helps the body bounce back from the cortisol surge that follows stress.50 In fact, an inverse relationship between cortisol and vitamin C has been observed in humans, suggesting that high cortisol levels – and the poorer health outcomes associated with them – may be caused by vitamin C deficiency.51 Low vitamin C is also correlated with fatigue in humans.52
Vitamin C helps the body bounce back from the cortisol surge that follows stress.
It is well accepted that substance use disorders are a maladaptation to trauma and stress.53 This means that supporting adrenal health may both prevent and treat addictions.
While vitamin C is stored in many places throughout the body, the highest concentrations are found in the nervous system and in the adrenal glands.54,55 Because humans cannot endogenously synthesize the nutrient, however, and because the adrenals secrete vitamin C as part of the stress response,49,55 our vitamin C stores become taxed in stressful situations. Supplementing with vitamin C through the diet and/or supplements may therefore be helpful during times of stress.50
In the case of animals that can produce their own endogenous vitamin C, it has been observed that their production of the nutrient increases 300 to 500% during times of stress, disease, and injury.56,57,58,59
A randomized, placebo-controlled human trial found that those who took 3 grams of vitamin C daily enjoyed lower blood pressure, faster cortisol recovery, and fewer subjective feelings of being “stressed” than those who didn’t get vitamin C.50
Finally, vitamin C may also help with OUD via analgesic (pain-killing) effects by playing a role in amidated opioid peptide production.60,61 Vitamin C is a cofactor for the enzyme peptidylglycine α-amidating monooxygenase (PAM),62 the only known enzyme that makes essential modifications to peptide hormone precursors in humans.63 Giving vitamin C to animals has been shown to increase the production of PAM-derived hormones.64
Vitamin C supplementation may support the synthesis of endomorphins, natural opioid neurotransmitters that relieve pain.
Vitamin C supplementation may thus support the synthesis of endomorphins, natural opioid neurotransmitters that relieve pain. Inadequate vitamin C levels may lead to a lack of analgesic neurotransmitters and neuropeptide hormones and thus result in pain.
Correcting nutritional deficiency
While severe vitamin C deficiency (hypoascorbemia) can lead to the “pirate’s disease” known as scurvy,65 milder deficiencies of vitamin C can also wreak havoc our health.66 Specifically, people entering drug treatment and those with major depressive disorder (MDD) have been observed to have low plasma levels of vitamin C and other antioxidants. 67,68,69,70
People entering drug treatment and those with major depressive disorder have low plasma levels of vitamin C.
We know that people who use and abuse substances long term tend to have incomplete diets, compromised digestion, and resulting nutritional deficiencies.71 This is especially the case in OUD, as opioid drugs cause a slew of digestive troubles.72 Those digestive issues lead to poor nutritional intake, which then contributes to nutritional deficiencies, which cause poor stress coping and sub-optimal neurotransmitter production, which in turn reinforce addictive behavior.
In the human body, the highest concentrations of vitamin C are found in the nervous and endocrine systems,73 where it is essential to our pain-relieving, addiction-fighting biochemistry.61
Vitamin C is a potent antioxidant and anti-inflammatory agent. It is also necessary for the body’s normal stress response, and supports the synthesis of important neurotransmitters and possibly even endomorphins. In these ways, vitamin C may help prevent and treat opioid addiction.
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