It might come as a surprise, therefore, that a study in 2019 found no such benefits with peanut butter.
When researchers studied the whole nut and peanut butter eating patterns of more than half a million people, they found that only whole nuts were associated with a lower risk of cancer, respiratory and heart disease.
Because this was a population study, it couldn’t confirm the two outcomes were related. In fact, the paper explains that people who eat peanut butter are more likely to smoke and eat red meat, and less likely to exercise – all risk factors for heart disease.
Another explanation, the researchers state, is that people who eat nuts may be eating a range of different nuts and benefitting from their different vitamins and minerals, whereas people who eat peanut butter might not be eating any other types of nuts.
An earlier population study from 2015 found that eating nuts was linked to lower levels of diabetes, whereas peanut butter wasn’t.
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But there aren’t many intervention studies directly examining the effects of nut butters on our health. One study of 38 adults, where participants added either roasted, raw or salted almonds, or almond butter to their diets for four weeks showed that all forms of almonds lowered LDL cholesterol.
However, this was a small study. Despite the large evidence base showing the health benefits of whole nuts, research into nut butters is lags behind – and what studies there are suggest there could be huge differences between the two forms of food.
What we do know is that the less that a food is processed, the healthier it generally is. But the process of turning nuts into nut butters – which involves roasting, blanching and grinding the nuts – is minimal, says Kevin Whelan, professor of dietetic at King’s College London.
“Removing the skin removes a bit of fibre, but it’s not very much because the kernel still contains lots of fibre,” he says.