Caffeine is the naturally occurring alkaloid and stimulant in coffee, tea, cocoa, guarana, cola and other plant product beverages. A strong cup of brewed coffee will give you about 100 milligrams of caffeine, instant coffee around 80 milligrams, often less, and tea down around the 40 milligrams. It varies from product to product and how you prepare the drink.
Heath is an unlikely Mr. Olympia. He grew up on playgrounds in Seattle playing basketball. His backcourt mate on the 1998 state championship team at Rainier Beach High School was Jamal Crawford, still in the N.B.A. Heath, just 5 feet 9 inches and a naturally chiseled 175 pounds, got a Division I basketball scholarship at the University of Denver. He majored in business and averaged 1.3 points over four seasons.
Creatine kinase is expressed in eyes. The eyes can take creatine up from the blood via two different transporters, the classic SCL6A8 (creatine transporter) and MCT12. It seems that expression of the receptors and accumulation of creatine occur in a relatively higher level in photoreceptors, which perceive color. Similarly to many other tissues, they appear to protect the cells during periods of low oxygen availability.
In regard to the blood brain barrier (BBB), which is a tightly woven mesh of non-fenestrated microcapillary endothelial cells (MCECs) that prevents passive diffusion of many water-soluble or large compounds into the brain, creatine can be taken into the brain via the SLC6A8 transporter. In contrast, the creatine precursor (guanidinoacetate, or GAA) only appears to enter this transporter during creatine deficiency. More creatine is taken up than effluxed, and more GAA is effluxed rather than taken up, suggesting that creatine utilization in the brain from blood-borne sources is the major source of neural creatine. However, “capable of passage” differs from “unregulated passage” and creatine appears to have tightly regulated entry into the brain in vivo. After injecting rats with a large dose of creatine, creatine levels increased and plateaued at 70uM above baseline levels. These baseline levels are about 10mM, so this equates to an 0.7% increase when superloaded. These kinetics may be a reason for the relative lack of neural effects of creatine supplementation in creatine sufficient populations.