Landmark study of 200,000 people reveals surprising truth about processed foods and health

The new research adds to the growing pushback against blanket judgments on processed food

Ultra-processed foods have long been vilified by nutritionists, but they may be softening their stance after new research suggests what matters most for long-term health is the overall nutritional quality of a diet, not how processed the food is.

New research led by the Harvard T.H. Chan School of Public Health tracked more than 200,000 people across three separate long-term studies spanning thirty years.

Participants’ diets were sorted into four groups adhering to different eating habits: healthy and ultra-processed, healthy and minimally processed, unhealthy and ultra-processed and unhealthy and minimally processed.

Roughly half of the respondents went on to die or develop heart disease or type 2 diabetes over the study period.

As predicted, the healthier diets carried lower risk and poorer diets carried higher risk - but interestingly, this pattern held regardless of processing level.

An ultra-processed diet built on nutritious choices carried a similar risk profile to the more minimally processed one built the same way.

Lead researcher Dr Xiaowen Wang argued that processing itself isn’t the enemy; many ultra-processed staples like fortified cereals, wholegrain bread, and tinned beans still deliver fibre, nutrients and antioxidants.

Meanwhile, some natural foods like homemade cakes, fruit juices, potatoes, red meat, and white rice can just as easily undermine a healthy diet.

The scientists’ advice is to pay attention to what constitutes the majority of your diet, and not whether an item happens to be processed.

With this in mind, the researchers were careful not to give a blanket pass to junk food, namely items like burgers, chips, pizza, doughnuts, fizzy drinks and biscuits, still warranting limits.

The findings arrive against a backdrop of growing alarm over UPFs, which make up an estimated 56 per cent of daily calorie intake for the average Briton, which has been linked to harm across nearly every organ system.

Scientists are also probing whether UPFs play a role in rising bowel cancer rates among people under 50.

But this latest work adds to a growing body of opinion pushing back against a one-size-fits-all verdict on processed food.

The research was presented at Nutrition 2026, the annual conference of the American Society for Nutrition.