Lack of vitamin C can impair older people’s memory and other cognitive skills
Brain cells (neurons) contain comparatively large concentrations of vitamin C, a nutrient that helps us maintain a healthy nervous system in a number of different ways. Scientists have discovered that lack of vitamin C can affect the brain’s neural signaling. Consequently, a vitamin C deficiency can impair memory and other cognitive skills in seniors. This was demonstrated in a study from Flinders University in Australia. Mild cognitive impairment is widespread among older people and represents an early stage of dementia so it is important to get plenty of vitamin C every day throughout life.
Alzheimer’s disease, the leading cause of dementia, takes years to develop. On a global scale, dementia and Alzheimer’s disease become increasingly widespread as a result of the increasing number of seniors. According to a report from the American Alzheimer’s Association, 6.5 million Americans suffer from the disease, while 12-18 percent of adult Americans aged 60 years and older have mild cognitive impairment, which can be a precursor of dementia. Similar figures can be expected in other Western countries.
Although mild cognitive impairment (MCI) with poor memory and loss of other cognitive skills is not necessarily linked to Alzheimer’s disease, the symptoms can be pre-clinical in many cases.
MCI is widespread among older people so researchers from Flinders University in Australia wanted to see what factors contributed. It turns out that low levels of vitamin C in the blood are linked to impaired cognitive skills.
Vitamin C’s role in the brain and nervous system
The brain contains relatively large amounts of vitamin C, a nutrient that is important for the development of neurons, the synthesis of neurotransmitters, and the formation of fatty myelin sheaths that surround and protect neurons and promote the transmission of impulses between neurons.
Vitamin C is also a powerful antioxidant that protects neurons against oxidative stress caused by free radicals.
Our energy metabolism and other metabolic processes generate free radicals. The free radical burden is increased by ageing processes and exposure to toxins. Free radicals are highly reactive molecules that must be kept on a tight leash and controlled by antioxidants such as vitamin C in order to avoid oxidative stress and damage to healthy tissue.
Vitamin C also contributes to the reduction of harmful iron and copper ions in the brain. A vitamin C deficiency can therefore result in oxidative damage to macromolecules in the brain, and the myelin sheaths that protect the neurons are particularly vulnerable.
It has been known for a long time that vitamin C is a vital constituent of collagen and that scurvy is the extreme, final stage of vitamin C deficiency with life-threatening, internal bleeding. This stage is preceded by extreme fatigue and mental disturbances. Although scurvy is very rare in the developed countries, subclinical scurvy is quite common, especially among seniors. Sub-clinical scurvy is associated with bruising, poor wound healing, impaired immunity, fatigue, and depression.
- Vitamin C is also known as ascorbic acid
- The concentration of vitamin C in the brain is around 100 times greater than in the bloodstream
- The brain has a formidable ability to remove vitamin C from the bloodstream
Previous studies have already shown that vitamin C plays a major role in the brain and that lack of the vitamin is linked to loss of cognitive skills, depression, and confusion. The scientists behind the new study compared cognitive skills and vitamin C levels in 160 hospitalized people aged 75 years and older. The cognitive skills were assessed by means of the Mini Mental State Examination (MMSE) and the Clock-Drawing Test (CDT). MMSE uses a 30-point scale that focuses on sense of direction, memory, attention, concentration, lingual skills, and visuospatial function.
In the CDT test, the participants are asked to depict different times of the day by marking the hours and minutes on an empty clock face. This task requires the use of several different cognitive, visual, and physical skills.
The reason why the scientists wanted to include the CDT test is that it is highly sensitive and specifically suited for detecting mild dementia. The test can also distinguish patients with mild cognitive impairment from healthy individuals. By combining these two different tests you increase the chances of detecting dementia and other types of cognitive impairments.
Widespread vitamin C deficiency and how it impairs loss of cognitive skills in old age
The scientists found that more than half (57%) of the patients in their study had cognitive impairment, while 26 percent had vitamin C levels lower than 11 micromoles/L and had borderline scurvy.
The study revealed that the cognitive score was significantly lower in patients who lacked vitamin C. In fact, further analyses showed that being vitamin C-deficient was linked to a more than times greater risk of cognitive impairment after adjusting for confounding factors.
The study also demonstrated that patients who had borderline or actual vitamin C deficiency showed signs of symptoms normally linked to subclinical scurvy. Many older people suffer from bleeding gums, bruising, and other skin problems that can also be caused by other factors. According to the scientists, it is important, no matter what, for hospitalized patients to have their vitamin C levels measured in case a deficiency is suspected.
The new study is published in Antioxidants.
How much vitamin C do we need?
Vegetables, fresh fruit, herbs, and berries are all good sources of vitamin C. Food loses a lot of its vitamin C content when it is frozen, fried, or stored for longer periods of time. The daily reference intake (RI) level for vitamin C in Denmark is 80 mg. The requirements for the nutrient may vary from person to person, so some people may need even more.
It appears that certain factors increase the need for vitamin C. This goes for things such as ageing, stress, smoking, and drug abuse.
A normal multivitamin typically contains around 80-100 mg of vitamin C, while vitamin C supplements typically contain 500 – 1,000 mg. It is a good idea to choose non-acidic sources of vitamin C (such as calcium ascorbate) that are gentle on the stomach.
Vitamin C content in mg per 100 grams of food
Y. Sharma et al. Relationship between Vitamin C Deficiency and Cognitive Impairment in Older Hospitalized Patients: A Cross-Sectional Study. Antioxidants 2022
Danielle Masterson. Low vitamin C linked to cognitive impairment in older adults. NUTRAingredients-usa.com
Hara Estroff Marano. The Cognitive Benefits of Vitamin C. Psychology Today 2018
Pernille Tveden-Nyborg og Jens Lykkesfeldt. Vitaminer til hjernen. Aktuel Naturvidenskab, nr. 4 2016
Frida - Database med fødevaredata udgivet DTU Fødevareinstituttet (fooddata.dk)
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