To date, there have been two hypotheses about how it protects organisms. One is water replacement
presumption which supports that trehalose can replace water to form hydrogen bond with biological
molecules when cells lose water, so the molecule can keep primary structure not losing its biological activity.
The other assumption is trehalose’s glass-forming ability[14]. It insists that trehalose can form glassy state
and resemble glass state of ice after its glass transition temperature (Tg), and then it packs biological molecule
tightly. The result is that the molecule has enough space in losing water case to resist destroy of harmful
surroundings. And this transition to the glassy state or the vitrification theory has been put forward as the
most widely accepted hypothesis to explain the bioprotective action of trehalose. No matter which point was
right, it could not influence its application. For example, Experiments have confirmed that it could help
treating dry eye[15]. Experiments have confirmed that externally added trehalose (there was no trehalose in
mammals) was a better treatment for moderate-to-severe dry eye syndrome in comparison with two
commercially available eyedrops. The reason might be that trehalose is a natural substance. Moreover,
trehalose plays an osmoprotective role in physiological responses, enabling the plants to better tolerate the
adverse effects of abiotic stress[16].