You can’t beat a big spoonful of vibrant green guacamole alongside a spicy Mexican vegan chilli. But be careful – it can easily turn into a grey sludge if you leave it for too long or don’t add enough lime juice. The discolouration is a natural reaction between fruit and the air, a process called oxidation. The same process causes apple slices to brown when exposed to air.
It’s not just fruit that does oxidation, it happens in your body. ‘Oxidative stress’ is thought to play a role in ageing, leading to wrinkled skin and brown skin patches, cataracts and age-related macular degeneration, plus a number of chronic diseases, including heart disease, cancer, diabetes and Alzheimer’s. It’s ironic that oxygen, an element that’s essential for life, can have such a damaging effect on the body.