People have a natural instinct to eat healthy foods, rather than simply being drawn to greasy, sugary snacks, a study has suggested.
Researchers from the University of Bristol found that people seem to be drawn to specific nutrients – and not energy-dense foods.
Previously, scientists had thought that humans had evolved to favour foods rich in energy and had achieved a balanced diet simply by eating different foods.
The Bristol team found that people seem to have "nutritional wisdom", whereby foods are selected in part to meet our needs for vitamins and minerals.
Lead author Jeff Brunstrom, professor of Experimental Psychology, said: "The results of our studies are hugely significant and rather surprising.
"For the first time in almost a century, we've shown humans are more sophisticated in their food choices, and appear to select based on specific micronutrients rather than simply eating everything and getting what they need by default."
The paper, published in the journal Appetite, gives renewed weight to bold research carried out in the 1930s by US paediatrician Dr Clara Davis, who put a group of 15 babies on a diet that allowed them to 'self-select', in other words eat whatever they wanted, from 33 different food items.
While no child ate the same combination of foods, they all achieved and maintained a good state of health, which was taken as evidence of nutritional wisdom.
Professor Brunstrom's team developed a novel technique that involved measuring preference by showing people images of different fruit and vegetable pairings so their choices could be analysed without putting their health or wellbeing at risk.
In total, 128 adults participated in two experiments. The first study showed people prefer certain food combinations more than others. For example, apple and banana might be chosen slightly more often than apple and blackberries.
The choices seem to reflect amounts of micronutrients in a pair and whether their combination provides a balance of different micronutrients.
The researchers cross-checked their findings with real-world meal combinations as reported in the UK’s National Diet and Nutrition Survey.
This showed that people combine meals in a way that increases exposure to micronutrients in their diet.
Specifically, components of popular UK meals, for example fish and chips, or curry and rice, seem to offer a wider range of micronutrients than meal combinations generated randomly, such as chips and curry.
Professor Brunstrom said: "Far from being a somewhat simple-minded generalist, as previously believed, humans seem to possess a discerning intelligence when it comes to selecting a nutritious diet."
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