An orange at breakfast, peppers at lunch, a kiwi as a snack: vitamin C starts with variety on your plate. Here is how to navigate food sources, everyday functions and the label.
01 · What it does
Also called ascorbic acid, vitamin C helps the body make collagen, acts as an antioxidant and improves iron absorption from plant foods. It also supports normal immune function. Functions explained by NIH.
02 · Beyond citrus
Peppers, kiwis, strawberries and broccoli offer other ways to include it in your day. A varied, balanced diet is the starting point; prolonged storage and cooking can reduce vitamin C in food. Food sources from NHS and storage guidance from NIH.
03 · Immunity does not mean preventing every cold
For most people, vitamin C supplements do not reduce the risk of catching a cold. Regular use may slightly shorten an episode; starting after symptoms appear does not seem helpful. What the research shows.
04 · Milligrams and NRV: two different numbers
Milligrams express the amount. The NRV percentage compares it with a labelling reference value: for vitamin C, this is 80 mg in the European Union. Thus, 500 mg equals 625% NRV. This percentage is neither an individual dose recommendation nor a measure of product effectiveness. EU Regulation 1169/2011, Annex XIII.
05 · Make an informed choice
Check the amount in the stated daily serving, including any other supplements you use. High doses can cause digestive problems. If you have haemochromatosis, another medical condition or take medicines, speak with your doctor before use. Precautions and interactions.
The Bio-Clock formula
Find ingredients, pack size and directions in the Bio-Clock Vitamin C product page. For the multipack, see the 3-pack.
Updated 7 October 2026. Food supplements do not replace a varied, balanced diet and a healthy lifestyle.