when you exercise a lot your immune system can be compromised. it's particularly important that gym-goers & sportspeople guard against being short of vitamin c as it keep the immune system working at full capacity & supports the production of strong collagen & cartilage.the body can not store vitamin c so you plan to supplement your diet you either need to take it in small amounts through the day or choose a high-dose time release product. this one is ideal: delivering 1000mg in micro-pellets so it is absorbed slowly into the bloodstream over 6-8 hours. along with immune system protection & enhanced collagen production vitamin c helps protect the body's cells from oxidative stress caused by free radical damage. more than just vitamin c with bioflavonoids & rosehips longer lasting released over 6 hrs unbelievable value our top seller at just 7p/day