The length of time it takes for platelet counts to increase depends on both the cause and the treatments used. Platelets are continually produced and replaced and have an average lifespan in the bloodstream of eight to 10 days (when not broken down by the immune system, involved with clotting, or other conditions that may affect this). Therefore, in theory, you should be able to see the effects of changes you make within only a few weeks. That said, dietary changes may not lead to rapid change. For example, if you are very low on nutrients (such as folate or iron), it could take a while to build up your body stores of these nutrients.