Unproven diet claims (alkaline, juice, 'anti-cancer' diets)

The alkaline diet claims foods change blood pH and that acidic conditions cause cancer; blood pH is homeostatically fixed and diet cannot alter it, and tumour microenvironment acidity is a consequence of tumour metabolism, not of diet. Gerson therapy (juices, coffee enemas, supplements) has caused electrolyte deaths and has no evidence of efficacy; amygdalin/laetrile is cyanogenic and has been shown ineffective in an NCI trial. A 2018 JNCI study found patients choosing alternative medicine alone had 2.5 times the mortality of those receiving conventional treatment. These claims spread through social media, wellness marketing and, occasionally, licensed practitioners; they exploit the real evidence that diet affects cancer risk. Countering them requires clinicians to ask about diet and supplements without judgement and to offer evidence-based dietitian support, so that the vacuum is filled by something better.