Chris' ad hoc assessment of aldehyde risks is right on target. Aldehydes are very low because all biological systems that convert alcohols to aldehydes also convert aldehydes to carboxylic acids. There are two problems that can crop up, (1) an imbalance in enzyme function between alcohol dehydrogenase and acetaldehyde dehydrogenase which allows acetaldehyde to build up, and (2) a weakness in aldehyde detoxification systems (i.e., glutathione, and to a lesser extent, other reduced-sulfur substances). People with these problems generally do not handle alcoholic beverages gracefully, so they learn pretty fast to avoid ferments and booze. They also tend to be chemically sensitive, reacting to "sick" buildings, particle board, new carpet, perfumes, smog and other oxidative stresses more than other people. Since microbes in the human gut ferment alcohols into aldehydes on a daily basis, the healthy gut (metabolically and physiologically) can easily adapt to a slight increase from fermented foods and beverages. Since sugar also ferments into alcohol, acetaldehyde and acetic acid, there is always some degree of an aldehyde influence. Being paranoid about this without any evidence of adverse reactions is likely counterproductive. Thank you Chris for a wise analysis in the absence of hard data.
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