There's well-established evidence that nuts are good for us. They're packed full of fibre and healthy fats, and have been linked to a lower risk of cardiovascular disease and cancer.
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.