The rationing system during and after World War II improved the health of the British population.

If during pregnancy a future mother consumes foods high in fats, it may trigger rapid weight gain and an increase in the fetal fat mass in the early stages. Furthermore, such a diet might be associated with a heightened risk of obesity in the child, which is known to increase the likelihood of developing type 2 diabetes and hypertension (high blood pressure). This hypothesis was proposed by Turkish scientists in 2023.

Establishing the causal relationship identified by the researchers from Turkey is challenging: it requires forcing subjects to adhere to specific diets, which may be unethical. However, there are instances that can substitute for such experiments and provide researchers with equally valuable information, as utilized by Tadeja Gracner's (Tadeja Gracner) team from the University of Southern California (USA).

Gracner and her colleagues studied the impact of sugar exposure on the body over 1000 days from conception, using a situation that arose during World War II in Britain. They accomplished this through a quasi-experiment — a type of experiment where researchers do not directly influence the participants or the conditions but instead utilize existing groups.

In January 1940, a few months after Germany declared war, the British government introduced a rationing system and started regulating food distribution. For instance, adults were limited to a sugar intake of 40 grams per day. More than a decade later, in September 1953, ration cards were abolished, and the British quickly doubled their sugar consumption.

Gracner's team analyzed medical records of over 38,000 individuals who were examined from 2006 to 2019. At the time of the study, the participants' ages ranged from 51 to 66 years, all of whom were conceived several years before the rationing system was lifted. Thus, the subjects were exposed to sugar either while in the womb or in early childhood.

The researchers also analyzed medical data from 22,000 individuals conceived a year after the abolition of food rationing. Both groups were similar in gender and race, and they had comparable family histories of diabetes (the disease is present in close relatives — parents, siblings), which allowed for a more effective comparison between the two groups.

In both groups, nearly four thousand individuals were diagnosed with type 2 diabetes, and 19.6 thousand had hypertension. However, the development of both diseases in those born during and after the rationing period differed significantly.

It turned out that individuals from the first group had a 35 percent lower chance of developing type 2 diabetes by age 60, and for those who did develop it, this occurred on average four years later than for individuals conceived after the rationing system was lifted. Regarding hypertension, the risk of this disease by age 60 was 20 percent lower in the first group compared to the second, with an average delay in disease development of two years.

It is important to note that while the food rationing system altered the British diet, it seems that the significant factor was the reduction in sugar consumption. During the rationing period, the diet of British residents included the same types of food (fruits, dairy, grains, meat) as after the abolition of the system. However, with the end of the rationing system, the British began to consume these products in greater quantities.

Gracner explained that sugar consumption in early childhood likely fosters a lifelong preference for sweets. This may also lead to epigenetic changes that increase the risk of developing type 2 diabetes and hypertension in adulthood.

Some experts believe that individuals conceived during the rationing system were healthier not because they consumed less sugar per se, but due to another reason: a lower caloric intake resulting from reduced sugar consumption. During the rationing, the British consumed about 100 calories less per day, and the risk of obesity for those conceived during the rationing period was 30 percent lower than for those born after the system was lifted. According to specialists, this indicates that the reduction in calories played a crucial role.

In any case, the work of Gracner's team has been positively received by dietitians. In their study, the researchers showed that reducing sugar intake to recommended levels significantly improves well-being. According to the WHO, adults and children should reduce their daily sugar intake (both natural and added) to less than 10 percent of their total energy intake. Further reduction to less than five percent, or about 25 grams (six teaspoons) per day, would provide additional health benefits.

The research by Gracner's team has been published in the journal Science.