Ever since its discovery in the 1930s, there’s been a debate about how much vitamin C should be taken and whether there’s a difference between vitamin C found in organic food and artificial vitamin C. 

Can we get enough vitamin C from food? 

While most animals can produce vitamin C from blood sugar, humans have lost this ability through gene mutation. Our ancestors supposedly originated from around the Equator where plentiful vitamin C rich fruits were readily accessible, so they did not need to produce vitamin C. Nowadays, however, as a result of modern agricultural practices, the vitamin C content of food is steadily decreasing; storing and heat treatment can further reduce it. As a result, it’s more important than ever to somehow supplement foregone vitamin C. (1, 2,) 

So how much vitamin C should be taken? 

The officially recommended daily intake of vitamin C is between ~60-110 mg depending on the region, but it’s likely that more vitamin C is needed for the proper function of the body. 

Various infections, intense physical activity and smoking all increase the body’s need for vitamin C. This is suggested by the fact that vitamin C supplementation decreased the risk of catching a cold and the duration of illness by half in sportspeople; in addition, the vitamin C levels of smokers are much lower compared to non-smokers. (3) (4) Studies which found vitamin C supplementation beneficial typically used a 500 mg or higher dose. 

Proper absorption is essential 

Familiarity with the absorption of vitamin C can likewise help determine the necessary amounts of vitamin C intake. Up to 200 mg nearly 100% of the vitamin gets absorbed; above 500 mg, however, the percentage starts to decrease. A daily intake of 1000 mg covers the entirety of the necessary supply, though even higher doses did not increase the body’s vitamin C level.(5) 

If one eats plenty of fruits and vegetables, a daily intake of 200 mg vitamin C can be supplied through organic food, but doses between 500 mg and 1000 mg would be extremely difficult to cover through nutrition alone.   

Is there a difference between organic and artificial vitamin C? 

Organic food and artificially produced vitamin C contain the same l-ascorbic acid molecule. Several studies examined whether there’s a difference between ascorbic acid found in food or food supplements, and found no difference. 

Even if there were  a difference in absorption, it would not be caused by the form of vitamin C but other ingredients in organic food. Effect-wise, artificially produced ascorbic acid fulfils all the functions of vitamin C; additional ingredients found in fruits and vegetables, such as polyphenols, can influence the absorption and utilization of vitamin C. (7) 

A benefit of organic food is that it contains all these ingredients, though its vitamin C level is often quite low. Thankfully, various supplements which include not only vitamin C but its cooperative active ingredients  are available for purchase, so one does not have to worry about deficit. 

Contradictory studies? 

Several studies have proved that intense supplementation and higher levels of vitamin C significantly reduce the risk of chronic illness and increase life expectancy. (8, 9, 10) On the other hand, multiple studies found that vitamin C supplementation does not result in the expected risk reduction of the same chronic illnesses. How is this possible? 

It’s often the case that the methodology of the study is not appropriate; some studies do not check the initial vitamin levels of participants. 

Plenty of people have been consuming vitamin C for decades, so the extra quantity supplemented during a study won’t have further effects on those who’ve been supplementing a high dose already. It follows that vitamin C supplementation is most effective for those whose vitamin C intake was previously insufficient. 

Doesn’t only depend on vegetables 

Many argue that higher levels of vitamin C is only beneficial since it means one presumably eats a lot of fruits and vegetables. However, in fact there’s a stronger connection between high vitamin C levels and lower risk of illness than frequent fruit- and vegetable consumption and health.  

In the Nurses Health Study, which followed over 85000 nurses through several decades, researchers concluded that vitamin C supplementation decreases the risk of cardiovascular diseases by 28%, while frequent fruit- and vegetable consumption only decreases it by 14%. (10) 

Accordingly, it takes a dose somewhat higher than the official recommendation to reach adequate levels of vitamin C and reap the benefit of the lowest risk of illness. Besides eating fruits and vegetables, vitamin C can be supplied through various supplements, which provide a practical solution to everybody

Additional information by Bence Szabó Gál: Although more than 1000mg really does not raise vitamin C levels any further, in order to remain at that level, it is necessary to take about 1000 mg every few hours. (I would like to add that an amount above 1000mg taken on an empty stomach can increase it even further, in the short term for about 20 minutes, it can increase it as much as you like because passive transport occurs there. So if you take, for example 10 thousand mg, it will be 100% absorbed, which increases its levels incredibly for a few minutes, but the level drops very quickly to the "1000 mg level" because it is quickly excreted by the kidneys). The point is that taking 1000mg a day only maximizes the Vitamin C level in the short term for a few hours, but 500-1000mg taken a few times a day maximizes it. (whether it is worth maximizing it is a question, but the answer is probably yes, as long as we are talking about a physiological level, i.e. up to 220 microM/l... higher than this is only possible with an intravenous or liposomal solution, and this has a pro-oxidant effect and it would be useful only in case of an infection or cancer, but not in other cases.)