Vitax Forskolin iron and thiamine, but none of these ingredients are available in doses high enough to compete with the benefits provided by HCA. - Second , we can conclude that HCA is not very effective when taken alone. HCA binds naturally to calcium within Vitax Forskolin. This reduces bioavailability by at least 50%. This is believed to be the reason why many early studies of HCA did not produce significant weight loss results. - Third , it can be concluded that, based on at least three separate studies, HCA is more effective when bound with salt, so HCA-SX was created.