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Riavita C+D vitamin + Quercetin

Science behind

Science behind

C+D Vitamin +Quercetin

The role of vitamins in health maintenance is an important area of research to this day

Research on the effects of vitamins mostly focuses on eliminating deficiency and restoring normal physiological functions. If the condition of a disease improves after vitamin supplementation, it can be assumed that the given vitamin has a role in the process. Recently more and more research is emerging that specifically addresses the health effects of extra daily intake of vitamins.


Scientific background...

As an antioxidant, Vitamin C supports the immune system in a relatively non-specific way through the balance of oxidative processes. Although the recommended minimum daily intake is 80 mg, many researchers are interested in the effect of a daily vitamin C intake of 1000 mg on various diseases.

Serum levels of both vitamin C and vitamin D are known to be inversely related to tiredness, meaning that their deficiency leads to fatigue. In a study of 62 people, participants who complained of general body pain, neck and back pain and fatigue were treated with vitamin D, and as a result, their condition began to improve rapidly.

Survivors of the stroke suffer from a high degree of fatigue and depression during the recovery phase. According to a British study, one of the reasons for this is vitamin D deficiency. All participants who received vitamin D supplementation had improved parameters. The results were also confirmed in a Chinese study of more than 500 patients recovering from an ischemic stroke.


  • Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients. 2020; 12(1): 228.
  • Decrease in Serum Vitamin D Level of Older Patients with Fatigue. Nutrients. 2019; 11(10):2531.
  • Vitamin D Levels in Patients Presenting with Non-Specific Neuromuscular Pain and Fatigue in Ethiopia. EJH Sci. 2020; 30(3):337-346.
  • Does Vitamin D Deficiency Predispose to Post Stroke Fatigue? Ir Med J. 2020; 113(2):23.
  • Effect of Vitamin D Supplementation on the Prognosis of Post-stroke Fatigue. Front Neurol. 2021; 12:690969.

It has been known since the 1940s that vitamin C deficiency can lead to high cholesterol and triglyceride levels. In severe vitamin C deficiency, cholesterol can build up in the liver to the point that it can harm the liver. In people with deficiency, taking the right amount of vitamin C has reduced blood cholesterol levels and improved cardiovascular performance.

A typical vitamin C deficiency disease is scurvy, when the walls of the capillaries become fragile and bleeding occurs. Collagen is present in the vessel wall and vitamin C is a co-factor in collagen synthesis, so if it is not present in sufficient amounts, the structure of the vessel wall will become damaged, and it can become permeable.


  • Vitamin C in Disease Prevention and Cure: An Overview. Indian J Clin Biochem. 2013; 28(4): 314–328

A termékről (általános információ)

(a régi termék oldal "Termék leírás" része)

Vitamins are essential for the normal functioning of our body. Inadequate vitamin intake can lead to deficiency diseases that are worsening within weeks or even days.

To avoid this, experts have defined the minimum daily intake. In case of water-soluble vitamins it is really worth to ingest the determined minimum, while in the case of fat-soluble vitamins, it is also good if the ingestion is uneven through the days of a week, unless on a weekly basis, sufficient amount is consumed. In addition, the daily upper level of vitamin intake (the amount that can be safely ingested) is very high, thus it is difficult to overdose them. For example, Vitamin C and Vitamin D can be consumed in several times higher amounts than the minimum recommendation, without putting a burden on the body. Moreover, many scientific research papers suggest that is is not only recommended to ingest the right amount of daily dose, but is is preferred to exceed it in certain cases, as extra vitamin intake can be beneficial for the health.

Vitamin D

Vitamin D is unique among vitamins both in the terms of structure and properties. It is fat-soluble, therefore our body can store it for up to a month. Still, even a large daily intake is considered safe. Currently, the tolerable daily upper limit is 4000 IU (international unit). Vitamin D is commonly known as a main supporter of the immune system: it makes us more resistant to certain infections. Additionally, it helps the absorption of calcium and phosphorus and in the proper growth and development of bones and teeth. Moreover, its antidepressant-like effect was also observed. Insufficient Vitamin D levels lead to fatigue, muscle weakness, physical pain and more fragile bones.

Vitamin C

Perhaps the best known and most popular vitamin. Vitamin C was discovered by Albert Szent-Györgyi in 1928 when he was looking for the cure for scurvy. Later, he was awarded the Nobel Prize in 1937 for his exploration of the cellular oxidation processes, including the antioxidant role of vitamin C. Vitamin C became the antidote to scurvy, which he could extract from lemon juice and from Hungarian red pepper in an amount that was sufficient to treat his patients.

Ever since, Vitamin C is one of the most commonly used substance in disease preventing home remedies, it is available in many forms and combinations. By supporting our antioxidant system, it protects the body against free radicals coming from our environment or produced in our body. Among the many functions of vitamin C, the most important are reducing the risk of certain chronic cardiovascular diseases, reducing the chance of developing gout by lowering uric acid levels, and helping to absorb iron and support the normal functioning of the immune system. Many people say that it also plays an important role in preventing and treating colds.

Vitamin C works together with many other antioxidants to help regenerate each other while keeping free radicals under control. With dietary antioxidants, e.g. together with a flavonoid called quercetin, the antioxidant capacity can be significantly increased.


Quercetin is a natural flavonoid, which has been detected in almost all plants to a greater or lesser extent. It plausibly has a role in the prevention of chronic diseases (such as cardiovascular diseases), and there are also scientific papers reporting about its immune system supporting effect, as well as about its direct antiviral effect. We also have several articles in our 'Science' section where quercetin appears. Click on the 'Quercetin' tag below to read more, for example about its effect against influenza or the coronavirus!

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