Key Summary
- Researchers looked at health data from nearly 65,000 UK adults born around the end of post-war food rationing.
- Babies who had restricted sugar in the womb and up to age two were 23 per cent less likely to develop dementia in older age.
- For those who did get dementia, people with low early sugar intake were diagnosed about 2.6 years later.
Eating less sugar during a baby's first two years of life -- including during pregnancy -- may significantly protect their brain health later in life, according to a major study published in the journal Neurology.
To test the long-term effects of sugar on the brain, researchers used the end of UK World War II sugar rationing in 1953 as a comparison. When sugar rationing ended, average sugar consumption in the UK doubled almost overnight.
By tracking health records for nearly 65,000 UK Biobank participants, scientists compared adults born during sugar rationing with those born right after restrictions lifted.
The study showed that limiting sugar intake in pregnancy and through a child's first two years:
- Lowered dementia risk by 23% compared to children born after rationing ended.
- Delayed the onset of dementia by an average of 2.6 years for those who developed the condition.
- Supported better brain structure, with MRI scans showing healthier brain tissue and less damage in older age.
Researchers noted that about a quarter of this benefit came from lower rates of type 2 diabetes and high blood pressure in adulthood, which are known to increase dementia risk.
Jiazhen Zheng, lead author from the Hong Kong University of Science and Technology, said: “Our findings suggest that limiting sugar during the earliest stages of life may have lasting benefits for brain health. High sugar levels during pregnancy can cause health issues for mothers, which may affect how the baby's brain develops.”
Dr Sara Rodrigues, Senior Research Manager at Alzheimer’s Research UK, said: “This study helps us understand how brain health develops across our lifetime. However, it is an observational study, which means it shows a strong link but cannot prove that eating less sugar directly prevents dementia. More research is needed to fully understand this relationship.”
Zheng also said "further research is needed" to understand whether sugar was having this effect.
More evidence needed
One big issue is, it is impossible to know how much sugar each of the people in the study were actually eating, merely when they were born relative to sugar rationing.
"This evidence relates to people born in the 1940s and 1950s and so its applicability to young children today is limited -- for example, weaning took place earlier and this would have a large impact on the early nutrition of babies and children," said Richardson.
Prof Ian Maidment, professor of clinical pharmacy at Aston University, said: "It is an interesting idea, it helps inform debate, but in my opinion we need more evidence."
He said connecting "something that happened 80 years ago" and projecting that onto health now meant there were "loads" of other factors that could be playing a role.
Bahee Van de Bor, Consultant Paediatric Dietitian and British Dietician Association (BDA) Media Spokesperson, said that even when the study might not be accurate, it is still an important study.
“Parents should not assume that a product is low in sugar simply because it is marketed for babies or carries a ‘no added sugar’ claim. Ingredients such as honey, syrups, fruit juice and fruit juice concentrates all contribute free sugars. Puréed or concentrated fruit can also make products taste very sweet, even when table sugar has not been added.
"Nutrition labels show total sugars rather than free sugars, which can make products difficult to assess. Parents can look at the ingredients list, compare similar products and choose predominantly savoury foods, unsweetened yoghurt and finger foods that have not been routinely sweetened with fruit purées or concentrates.
"Breast milk or infant formula should remain a baby’s main drink until 12 months, with water offered from around six months. From age one, water and milk should be the main drinks.
"This is not about expecting parents to calculate every gram of sugar or prepare everything from scratch. Commercial baby foods can be convenient, but sweet pouches, desserts and snack products should not dominate a young child’s diet. Offering a variety of ordinary family foods, flavours and age-appropriate textures remains important.”
