The UK reference intake is 80mg a day, which a varied diet with fruit and vegetables can supply. Many people choose to take more, typically 500mg to 1,000mg, particularly during winter or periods of stress. Above around 1,000mg the body absorbs proportionally less and passes the rest, and higher amounts can cause loose stools. If you take more than 500mg, splitting it across the day is more effective than one large dose.

Standard vitamin C is ascorbic acid, which is mildly acidic. Buffered vitamin C binds it to a mineral, usually calcium or magnesium, which neutralises the acidity. It suits people who find plain vitamin C causes heartburn or stomach discomfort, anyone taking higher amounts, and those with sensitive teeth who take powder in water. The vitamin C content is the same; only the acidity changes.

No supplement can claim to prevent colds, and the evidence does not support that. What vitamin C does is contribute to the normal function of the immune system, and to maintaining normal immune function during and after intense physical exercise when taken at 200mg or more a day. In other words, it helps your immune system do its job, rather than stopping infections outright. A steady daily intake matters more than a large dose once symptoms appear.

Capsules give a fixed amount and are easy to take on the go. Powder dissolved in water lets you measure exactly what you want, adjust up or down, and take larger amounts without swallowing several capsules. Powder is also the practical choice for children or anyone who cannot take capsules. Both contain the same vitamin C.

Yes, and it is a useful combination. Vitamin C increases the absorption of iron from food and supplements, which is why our Iron & Vitamin C capsule pairs them. Zinc ascorbate combines zinc and vitamin C in one capsule for anyone who wants both without two separate products. If you take vitamin C with iron, keep tea and coffee at least an hour away, as they counteract the benefit.