Harvard researchers have correlated walnut consumption with a 17 percent lower risk of Type 2 diabetes and 29 percent lower risk of cardiovascular disease. 

The study, supported by the California Walnut Commission, set out to identify the precise components in walnuts that may be responsible for reducing the risk of these ubiquitous diseases.

Findings point to the specific metabolite profile of walnuts that may be responsible for promoting health. 

This is the first study to examine the association between walnut metabolites and the risk of cardiometabolic diseases, the authors write. 

These findings further emphasize the connection between walnut consumption as part of a healthy diet and cardiometabolic health.

However, the researchers conclude that the results do not prove cause and effect. More research is needed in other populations since this study was focused on older Spanish adults only. 

Researchers used AI to identify 19 metabolites that are associated with walnut consumption.Revealing metabolites
Researchers at the Harvard TH Chan School of Public Health in collaboration with investigators from Rovira i Virgili University and the University of Navarra, Spain, used a novel machine learning model – a subset of AI – to identify 19 metabolites associated with walnut consumption.

The body forms specific metabolites based on what food is consumed. 

“In this study, we revealed the unique metabolomic signature of walnuts, which brings us one step closer to understanding ‘how’ walnuts are good for our health,” says Dr. Marta Guasch-Ferré, lead investigator of this research and scientist at the Department of Nutrition at Harvard TH Chan School of Public Health.

Analyzing the data 
Researchers examined data from 1,833 participants of the PREvención con DIeta MEDiterránea (PREDIMED) study. 

This was a large-scale, multi-year study that took place in Spain and looked at the effects of a Mediterranean diet in the prevention of cardiovascular disease among people at high risk for heart disease. 

Participants were aged 55-80 and followed one of three diets:  

• Mediterranean diet supplemented with mixed nuts (50 percent walnuts, 25 percent almonds, and 25 percent hazelnuts). 
• Mediterranean diet supplemented with extra-virgin olive oil. 
• Low-fat diet. 

Leveraging AI
Machine-learning models like the one used in this epidemiological study may help further research into diet and how it affects individuals. 

“With data-driven technologies, we are able to enhance our understanding of the relationship between diet and disease and take a personalized approach to nutrition which will lead to better prevention and management of various health conditions,” says Guasch-Ferré.

“These cutting-edge technologies are shaping the future of nutrition recommendations.”

Given the field of metabolomics is rapidly evolving, future studies will be needed to identify additional biomarkers of walnut intake that were not pursued in this study. 

More research is also needed to understand individual metabolic responses after consuming walnuts.

Furthering walnut research
In a recent study that compared variations of the Mediterranean diet, walnut intake combined with lower red or processed meat consumption was significantly associated with lower intrahepatic fat levels after controlling other variables.

Meanwhile, a study in Spain found that the consumption of a mix of nuts (almonds, hazelnuts and walnuts) for 14 weeks significantly improved sperm count, viability, motility and morphology.