“Also steaming rather than boiling vegetables is much better, anything that you cook in high temperatures for a long time seems to be the more problematic, reducing the nutrition qualities or generating some of these problematic compounds, like acrylamide,” says Macciochi.
Another problem with frying, or other cooking methods involving oil, is what happens when certain fats are heated up. It turns out heat can cause oils to undergo a series of chemical reactions, so when you cook them at high temperatures, you risk ending up with a subtly different ingredient to the one you started with.
Not all oils are equally susceptible to these changes. For example, olive oil has a relatively low “smoke point”, compared to saturated fats such as coconut oil. This is the temperature at which it starts to change – when it begins to vaporise and lose some of its beneficial compounds, such as the anti-inflammatory oleocanthal. This is also the point at which it starts to produce harmful compounds, such as certain aldehydes. Macciochi still recommends olive oil for most cooking, because of how healthy it is to begin with – just not for industrial cooking, or anything involving long cooking times.
However, though some types of cooking come with risks, avoiding cooked food altogether has the potential to be far more damaging. One German study of people who ate a raw-food diet for a number of years, found that the men lost around 9kg of weight (19 lbs), while the women lost around 12kg (26 lbs). By the end of the study, a significant proportion were underweight – and around a third of the women stopped having regular periods. The authors concluded, with typical scientific understatement “a very strict raw food diet cannot be recommended on a long-term basis”.
“Ultimately cooking meat and cooking carbohydrates is a good way to increase the availability of nutrients from these foods, as opposed to eating them raw,” says Macciochi, “because imagine a raw potato, it is very difficult to get the nutrients of it, not to mention that it is just not enjoyable.”
It seems like our ancestors were on to something, after all.
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