More vitamin C is linked to less depression

Most people are unaware of vitamin C’s key role in mental health and mood. According to a large population study that is published in Frontiers in Nutrition, having higher levels of vitamin C in the blood is linked to a lower risk of depression. The official dietary recommendations for vitamin C only focus on preventing the potentially lethal deficiency disease called scurvy, and things like stress, ageing, stimulant use, overweight, infections, and chronic illnesses can increase your need for the nutrient.

The new study was based on the large population study called NHANES (Nutritional Health and Nutrition Examination Survey). A total of 3,404 participants filled in a health questionnaire (PHQ-9) and had their blood levels of vitamin C (ascorbic acid) measured. Afterwards, the researchers selected 299 participants, all of whom had been diagnosed with depression, plus a control group of 1,107 people who matched other parameters. They used a model called RCS (Restricted Cubic Splines) to investigate the relation between serum levels of vitamin C and the rate of depression.
The study showed that participants with depression on average had significantly lower serum levels of vitamin C (42.97 µmol/l) compared with the control group participants without depression (52.97 µmol/l). The same was the case after adjusting for possible confounders, which means there is a significant inverse relation between serum levels of vitamin C and the risk of developing depression.
According to the researchers, their findings shed new light on the importance of increased serum levels of vitamin C in the prevention and treatment of depression. In that connection, it is important to know that the dietary intake of vitamin C is not necessarily linked to serum levels of the nutrient.
Nonetheless, the study authors refer to 25 other studies with nearly 92,000 participants that also revealed a link between vitamin C levels and the risk of developing depression.

How does vitamin C protect against depression?

Vitamin C is a powerful antioxidant that protects cells and tissues against oxidative stress caused by free radicals. Everyone is exposed to free radicals, but factors like stress, smoking, alcohol abuse, poisoning, overweight, ageing, and chronic diseases like type 2 diabetes increase the free radical load.
Oxidative stress can damage nerve cells and the function of neurotransmitters that are directly linked to our mood and risk of developing symptoms of depression. Oxidative stress can also affect the hippocampus, which is the part of the human brain that controls memory and sense of direction, and it can even affect other parts of the brain that control our mood.
Vitamin C also counteracts the COX-2 enzyme and chronic brain inflammation, which increases our risk of depression.
In addition, vitamin C has the ability to protect nerve cells against premature apoptosis, which is programmed self-destruction carried out by damaged and worn-out cells.

• The vitamin C content in the brain is around 100 times higher than the vitamin C content in our blood.
• This demonstrates that the brain has a relatively large need for vitamin C to carry out different functions in the nervous system and to protect itself against oxidative stress.

How vitamin C reaches our brain, and how much we need

Some of the good sources of vitamin C are fruit, vegetables, and herbs. Vitamin C is absorbed in the small intestine and carried with the blood to the brain and different organs. The recommended dietary intake of vitamin C is 80 mg daily. Stress, infections, smoking, stimulant abuse, ageing, overweight, chronic diseases, and poisoning can increase the need for vitamin C because of increased free radical formation and oxidative stress.
Even minor vitamin C deficiencies can affect the brain and increase the risk of depression and other diseases. For that reason, vulnerable population groups should strive to get more vitamin C than the official recommendation.
When choosing vitamin C in supplement form it may be a good idea to stick with a non-acidic source that is gentle on the stomach. Excess vitamin C is excreted via the urine.

• Vitamin C is important for the synthesis of collagen in our connective tissue
• Scurvy is a deficiency disease where people die of internal bleeding caused by porous connective tissue.
• Sub-clinical scurvy is widespread and characterized by bruising, bleeding gums, nosebleeds, poor wound healing and/or a week immune defense.
• Vitamin C is also important for the immune defense, circulatory system, iron uptake, the brain, and the nervous system – plus it is a vital antioxidant.
• Tiredness, bad moods, and depression are known as early and non-specific signs of being vitamin C-deficient.

References:

Mengyuan Chen et al. Higher serum ascorbic acid levels are associated with lower depression prevalence in US adults: a case-control study. Frontiers in Nutrition. 2024

Pernille Tveden-Nyborg og Jens Lykkesfeldt. Vitaminer til hjernen. Aktuel Naturvidenskab, nr. 4 2016