Most people think of vitamin C in connection with the immune defense, but as it turns out, the largest concentration of vitamin C is actually found in the brain. This is because vitamin C is enormously important for the energy turnover, the nervous system, and the cognitive skills, and this is described in a new review article. There is also evidence of widespread vitamin C deficiency, which may eventually impair cognitive skills and increase the risk of dementia and Alzheimer’s disease. If a pregnant woman lacks vitamin C, it can disrupt the development of the baby’s brain. There is a number of factors that increase our need for the nutrient, so the big question is how much do we need to secure optimal brain function throughout life?
The human brain consumes massive amounts of vitamin C. The nutrient is important for the energy turnover, and it helps the neurons produce thoughts and feelings and supports movements and other functions. Vitamin C is also an important antioxidant that protects the neurons against oxidative stress. It has many other functions that relate to our physical and mental health, and many of these functions became known after Linus Pauling and W. A. Havorth were awarded the Nobel Prize in 1937 for the discovery and extraction of this essential vitamin.
Vitamin C’s many roles in the nervous system
Vitamin C is involved in the maturation of various neurons and the formation of lipid-containing myelin sheaths that protect our neurons and enhance the transmission of impulses between neurons. That is why vitamin C is so important for our cognitive skills.
Vitamin C is also important for the synthesis of neurotransmitters and the conversion of dopamine to serotonin that is crucial for our feeling of well-being and positively motivated actions. Science has known for a long time that vitamin C is a constituent of the collagen in connective tissue that is essential for the structure of our blood vessels, skin, gums, and bones. In the old days, thousands of sailors died of scurvy, which is the extreme consequence of being vitamin C-deficient and manifests itself as internal bleeding. The initial symptoms of scurvy are fatigue, mood swings, and depression, and these symptoms are rooted in the brain and nervous system.
Blood levels of vitamin C are related to cognitive skills
During the period between 1980 and 2017, Australian scientists reviewed 50 studies that compared blood levels of vitamin C with cognitive functions such as language, learning skills, concentration, memory and orientation. The scientists took blood samples and measured the different cognitive functions, using a questionnaire called Mini Mental State Examination (MMSE). They found a significant correlation. First of all, those study participants whose cognitive skills remained intact, had significantly higher levels of vitamin C in their blood compared to study participants with cognitive impairment.
Other studies have shown that impaired immune defense, fatigue, depression, bruising, and poor wound healing are a sign of being vitamin C-deficient. A Danish research article published in the journal Aktuel Videnskab has suggested that maternal vitamin D deficiency may harm the development of the fetus.
|Most animals are able to synthesize vitamin C, but humans, apes, guinea pigs, and bats have lost this ability due to evolutionary changes and depend on getting the nutrient from their diets.|
Even minor deficiencies may harm the nervous system in the long run
According to the Australian review article, even minor deficiencies of vitamin C in the blood may result in weakened cognitive skills, whereas increasing your vitamin C levels may have the opposite effect. Study participants with insufficient levels of vitamin C in their blood were twice as likely to develop cognitive impairment compared with the participants that had enough vitamin C.
Several studies of short-term vitamin C supplementation have showed conflicting results, so it seems likely that it is primarily a chronic vitamin C deficiency that causes loss of neurons in connection with dementia and other psychiatric disorders.
|It is interesting to consider that fatigue, bad mood, and depression are known as early but non-specific signs of being vitamin C-deficient.|
Vitamin C protects against oxidative stress, dementia, and Alzheimer’s disease
Oxidative stress is when the balance between harmful free radicals and protective antioxidants is disturbed. Free radicals are aggressive molecules that attack the lipids in cell membranes, setting off a chain reaction. The myelin sheaths of the neurons are particularly vulnerable to such attacks. We are all exposed to free radicals, and the free radical burden is heavily increased by stress, poisoning, ageing processes, and radiation. Both dementia and Alzheimer’s disease are conditions that are characterized by oxidative damage to brain cells caused by free radicals.
Oxidative stress activates certain enzymes that promote the formation and accumulation of beta-amyloid plaque, a type of protein that is involved in the development of Alzheimer’s disease.
Oxidative stress prevents the clearance of toxic compounds and metabolic waste products from the brain, thereby increasing the risk of inflammation and cellular death. At the same time, it reduces the ability of neurons to burn glucose, which is their primary fuel. Our only way of protecting ourselves against oxidative damage is by getting enough antioxidants such as vitamins A, C, and E plus selenium, zinc, and various plant compounds.
Lack of vitamin C is rather common
There is widespread vitamin C deficiency. The CHALICE study from New Zealand showed that 62 percent of 50-year-olds from all income levels have too little vitamin C in their blood. The scientists also found a relation between cognitive functioning and blood levels of vitamin C.
Deficiency and poor utilization of vitamin C may be caused by unhealthy diets, stress, smoking, poisoning, lesions, ageing processes, and abuse of alcohol and narcotic drugs. Consuming too much sugar is also a risk factor, as sugar and vitamin C compete for the same channels that lead into the cells. The more sugar you consume, the more it reduces the effect of vitamin C.
Vitamin C content in mg/100 grams
How much do we need?
Fresh fruit, vegetables, herbs, and berries are good sources of vitamin C. However, a large amount of the nutrient is lost when you freeze, cook, or fry the food or store it for a long time. The reference intake (RI) for vitamin C in Denmark is 80 mg for adults and children older than 11 years of age. This may not be enough to cover our actual need though. If you have a healthy lifestyle without too much stress, tobacco, and stimulants, eating six daily servings of fruit and vegetables or a daily multivitamin is considered enough. Still, studies of more recent date show that even minor vitamin C deficiencies can cause serious changes to the brain. Vulnerable groups such people with chronic stress, smokers, older people, substance abusers, pregnant and breastfeeding women, and children with smoking parents should consume more than the officially recommended amount of vitamin C. Most multivitamins contain around 80-100 mg of vitamin C, whereas vitamin C supplements are more likely to contain 500-750 mg – or more. Make sure to choose a supplement with non-acidic vitamin C (calcium ascorbate) that is gentle towards the stomach.
Vitamin C in the brain
|Important: Our brain function depends on many factors such as diet, physical activity, and mental challenges.|
Hara Estroff Marano. Psychology Today 2018
Pernille Tveden-Nyborg og Jens Lykkesfeldt. Vitaminer til hjernen. Aktuel Naturvidenskab, nr. 4 2016
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