Vitamin C intake and multiple health outcomes: an umbrella review of systematic reviews and meta-analyses

Abstract

The purpose of this article was to assess the existing systematic reviews and meta-analyses for the association between vitamin C intake and multiple health outcomes. A total of 76 meta-analyses (51 papers) of randomised controlled trials and observational studies with 63 unique health outcomes were identified. Dose–response analysis showed that vitamin C intake was associated with reduced risk of all-cause mortality, cardiovascular disease (CVD), oesophageal cancer, gastric cancer, cervical cancer and lung cancer with an increment of 50–100 mg per day. Beneficial associations were also identified for respiratory, neurological, ophthalmologic, musculoskeletal, renal and dental outcomes. Harmful associations were found for breast cancer and kidney stones for vitamin C supplement intake. The benefits of vitamin C intake outweigh the disadvantages for a range of health outcomes. However, the recommendation of vitamin C supplements needs to be cautious. More prospective studies and well-designed randomised controlled trials (RCTs) are needed.

Keywords:

• Vitamin C
• health
• umbrella review
• meta-analysis
• systematic review

Disclosure statement

No potential competing interest was reported by the author(s).

Additional information

Funding

This work was supported by the Henan University science and technology innovation talents support program under Grant 19HASTIT005; the National Key Research and Development Program under Grant no. 2017YFC1309200; and Medical Science and Technology key projects of Henan Province and Zhengzhou under Grant 192102310088 and 19A32000820.