Examples from everyday life for diastereoisomers ?
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Carbohydrates

Glucose and galactose, two of the most common monosaccharides found in the body, are diastereomers of each other:



Lactose, which is found in milk, is formed by a condensation reaction between glucose and galactose.

Eyesight

Retinal is a molecule found in the photoreceptor cells of eyes that normally exists in the 11-cis form. When it absorbs light, it undergoes an isomerisation to form the all-trans form:



This forms part of the biochemical pathway by which light is converted into an electrical signal in the nervous system.