In 1993 Prof. Dr. Somlyai has discovered that cancer cells cannot tolerate low-deuterium environments (as low as 100 ppm). There is solid science behind. He and his workmate, Prof. Dr. Boros even buy the publication fee for their own scientific papers to make them available to the general public because they are open to recieve scientific criticism. The idea of deuterium depletion manifested in a therapy using deuterium depleted water, which is drank regularly or injected directly into tumors. It has been approved for animals and being used in therapy since 15 years with great success. The human experiments have succeeded to demonstrate that mentioned water significantly improves acute survival rate, and survival rate is significantly better after 1 year of treatment.
The authorities have declined to approve its use in humans because there were no significant improvement in survival rate after 3 years of treatment. So "we dont have a cure for cancer".
Life, since eucaryotic cells have appeared, thrive to deplete deuterium levels inside mitochondria because deuterium kills atpase enzyme, which produces the energy for the whole body. One method of doing this is to keep procaryote cells and fungi in the gut, which in turn tend to concentrate deuterium, which is required for their genes to multiply. Feces is therefore richer in deuterium, getting the body levels lower.
Ocean deuterium level is 155. When the water evaporizes, the steam has 2.5% - 4% less deuterium as the water. The cloud then moves around, and rains the deuterium-richer water first, leaving the deuterium depleted rain for the end. When clouds form around the equator, and they quickly fall in the form of summer thunderstorms, they tend to be higher in deuterium. But if the clouds form, move around through the poles, then back to 45 degrees latitude, they can reach the 130 ppm, which is tremenduosly good for mitochondria. We know that cancer is less prevalent as we go closer to poles.
The consequence of mitochondria having low deuterium levels is that they produce citric acid with low deuterium content, which later turns into fat. That's why lard has 118 ppm deuterium in it, which generally means that eating a ketogenic diet of such fats (and drinking as little water as needed) is super efficient in depleting deuterium in the body. It takes 2-3 months to reach the equilibrium of deuterium levels after a change in diet/lifestyle. The Wartburg-effect might be a consequence of this.
ppm is parts per million, which labels how many deuterium isotopes are present for 1000000 hydrogen atoms. So oceans have roughly one deuterium-containing water molecule every 6600 water molecules.
The above is basically what I understood researching the topic, please google Somlyai and Boros for more.