Market analysis of vitamin C-containing dietary supplements in Germany and the USA: Consumer information and risks and benefits.

The common cold and other flu-like illnesses are the leading cause of absence from work for adults and absence from school for children. Especially during the winter people look for an easily available and reliable way of preventing colds. Many studies have been performed on the effects of vitamin C on the common cold, and some studies have been conducted on the potential link between high doses of vitamin C and adverse effects such as kidney stones. This analysis aims to gather the available information on both beneficial and adverse effects and compare these findings to the current market of vitamin C-containing supplements. To get an accurate picture, this analysis was conducted to examine the market of vitamin C supplements further and inspect the labeling, dose, cost, and advertisement of 106 selected preparations sold by online stores in Germany and the USA. The goal was to determine what benefits and risks consumers can expect when taking the available products and if they are sufficiently informed by manufacturers. The mean daily therapy cost of vitamin C across all products was $ 0.37 for a mean daily dose of 613.9 mg. The recommended daily dose of vitamin C for adults is 90 to 110 mg and 100% bioavailability is reached from doses of 100 to 400 mg. Overall safety concerns were present among products from both Germany and the USA. For instance, more than three quarters of products exceed the recommended daily dose for vitamin C-containing dietary supplements and nearly 40% of all preparations transgress a potential upper safety level. Additionally, there were some issues with product labeling, as 12 to 14% of products from Germany and 5 to 20% of products from the USA were missing warnings that are legally required or recommended. Monopreparations were generally more popular than combination preparations. However, more than one-third of all products contained other active ingredients besides vitamin C which might increase the risk of overdoses especially if paired with other dietary supplements or multivitamins. While 80% of all products advertise vitamin C to boost the immune system, the benefits in regard to the common cold are slim, as regular vitamin C supplementation fails to lower the incidence of colds among the healthy general public. Adverse effects of even high doses of vitamin C are rare but caution is advised for people with limited kidney function or patients who have previously dealt with kidney stones. The mean daily doses of the products in this analysis will likely not lead to adverse effects among the healthy general public but might be unsafe for people who have experienced kidney stones before. In conclusion, the daily doses taken in the form of vitamin C supplements are often high, and consumers are not informed properly.