Cracking the Mysteries of Walnut Research

Walnuts are known to be a rich source of disease-fighting nutrients; they are often labeled a “superfood” and are key components of the Mediterranean diet. Yet as much as science has revealed about the health benefits of walnuts, their phytochemical makeup in large has remained a mystery to this point.

This new research approach is expected to create unprecedented research opportunities that will lead to a greater understanding of the walnut’s impact on human health.

The research study, “Efficient preparative isolation and identification of walnut bioactive components using high-speed counter-current chromatography and LC-ESI-IT-TOF-MS,” was published in the September 1, 2014 issue (volume 158) of the scientific journal, Food Chemistry.

Led by Dr. Mary Grace, a senior researcher in Dr. Mary Ann Lila’s lab at the Plants for Human Health Institute (PHHI), the research establishes a unique method for discovering and studying the compounds at the core of the walnut’s health-promoting properties. Grace and the team at PHHI discovered two new compounds in the walnut while developing the research process, and are quick to emphasize the importance of characterizing each individual compound.

“There are undiscovered natural components in walnuts that are likely to contribute to human health protection,” said Grace. “Developing an efficient way to isolate compounds will enable researchers to study how they work and then connect the dots back to the health benefits of consuming walnuts.”

Scientists have produced numerous studies linking walnuts with health benefits like weight management, cancer prevention and heart health. Recognizing the phytochemicals responsible for the health perks and extracting a large enough quantity for research trials, however, has been a struggle.

The PHHI researchers sought to develop a process that would harvest sufficient samples of walnut phytochemicals while achieving clean separations; compounds often become diluted during extraction or otherwise can’t be collected in adequate amounts. Utilizing the new methodology, researchers are now able to gather large enough phytochemical samples from walnuts to conduct animal and clinical trials that can validate the health-beneficial properties.

By gaining a better understanding of the unique phytochemicals in walnuts and the processes by which they promote human health, researchers may one day be able to treat certain ailments by recommending specific amounts of walnuts for consumption.

“Dr. Grace’s work has the potential to advance walnut health research for many years to come,” said Dr. Mary Ann Lila, a co-author of the study and director of the Plants for Human Health Institute. “Researching walnuts isn’t like juicing a berry, and up until now we’ve had to rely on less-than-optimal strategies to collect and investigate phytochemicals from walnuts. That’s no longer the case.”

Grace’s process is expected to add value to a crop that is already economically and nutritionally important. Walnuts are the second largest nut crop in the United States, which produces well over 900 million pounds annually with a production value of more than $1 billion. The U.S. is the world’s largest exporter of walnuts.

Walnuts are not only important commercially, but are valuable sources of omega-3 fatty acids, vitamin E, protein and antioxidants associated with heart health and may also inhibit the growth of cancer cells. Packed with proteins, healthy fats and a broad array of essential vitamins and minerals, they are considered a nutritional powerhouse.

The California Walnut Commission provided funding support to this research project.