Vitamin C overconsumption in the human system – clinical manifestations and recommended daily intake guidelines
Wojciech Wiśniewski
2026-03-24
4 min. read
Vitamin C overconsumption in the human system – clinical manifestations and recommended daily intake guidelines
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Due to the genetically determined inability to endogenously synthesize ascorbic acid—stemming from the absence of the enzyme L-gulonolactone oxidase, which catalyzes the final step of its biosynthesis—humans, along with other primates and guinea pigs, must obtain this essential vitamin exclusively from external dietary sources. As the season of heightened susceptibility to upper respiratory tract infections approaches, there is a noticeable surge in demand for dietary supplements containing L-ascorbic acid, which are available not only through brick-and-mortar pharmacy networks but also via alternative distribution channels, including online retailers and specialized health stores.
Daily intake of vitamin C
L-ascorbic acid is a widespread substance and a significant amount is found in fruits and vegetables (wild roses, black peppers, parsley, red pepper, celery, strawberries, kiwifruit, citrus fruits). It is also widely believed that the most significant source of vitamin C deficiency in the diet of a woman is a lack of vitamins, due to the increased intake of carbohydrates from her body, the low cost of this substance.
Overdose of vitamin C
It is assumed that on average with food we provide 7080 mg of vitamin C, which corresponds fairly well to the recommended daily intake [1].The problem may arise when we reach for a variety of vitamin preparations, available in any pharmacy, without a prescription. Although there have never been any symptoms of vitaminC overdose from eating vegetables and fruits or drinking fruit and vegetable juices, such a large amount of synthetic vitamin C taken as various preparations (above 2000 mg/hour) can cause kidney stones and stomach-to-mouth disorders.
Symptoms of an overdose of vitamin C
The human body is able to defend itself against an excess of vitamin C by limiting the absorption capacity of the intestine and removing the excess from the urine.[2] From a scientific point of view, vitamin C is not a toxic substance due to the lack of contraindications to its excess intake. However, it is not entirely known what dose of L-ascorbic acid can be too high. The body's reaction to this substance is an individual trait. Therefore, the preservation of particular safety while taking high doses of vitamin D is also valuable. According to the medical literature, there are several studies that provide nutritional benefits not only to the body but also to other nutrients and nutrients, which can be eliminated from the body at the same time. It is important to note that the use of C-albinoids in the diet is not only beneficial for the body, but also for the health and well-being of the body.