Sentence:  Mostly, the microbiome is beneficial. It helps with <WSD>digestion</WSD> and enables people to extract a lot more calories from their food than would otherwise be possible. Research over the past few years, however, has implicated it in diseases from atherosclerosis to asthma to autism. 
Meaning of the word marked with <WSD> tags:  The process, in the gastrointestinal tract, by which food is converted into substances that can be utilized by the body.