Consumption of whole walnuts or their extracted oil can reduce heart disease risk and boost cardiac health, a new study has found.
Researchers found that walnuts can improve heart health through a mechanism other than simply lowering cholesterol.
"We already know that eating walnuts in a heart-healthy diet can lower blood cholesterol levels," said Penny Kris-Etherton, Distinguished Professor of Nutrition, Penn State.
"Now we understand additional ways in which whole walnuts and their oil components can improve heart health," Kris-Etherton said.
In a randomised-controlled trial, the researchers gave 15 participants with elevated blood cholesterol one of four treatments - either 85 grammes of whole walnuts, 6 grammes of skin, 34 grammes of defatted nutmeat, or 51 grammes of oil.
The team of Penn State, Tufts University and University of Pennsylvania researchers evaluated biochemical and physiological responses in the participants before the treatments were administered and again 30 minutes, one hour, two hours, four hours and six hours after administering the treatments.
The researchers repeated this process for each of the remaining three treatments.
Results showed that a one-time consumption of the oil component in walnuts favourably affected vascular health.
In addition, consumption of whole walnuts helped HDL - good cholesterol - perform more effectively in transporting and removing excess cholesterol from the body.
"Our study showed that the oil found in walnuts can maintain blood vessel function after a meal, which is very important given that blood vessel integrity is often compromised in individuals with cardiovascular disease," said Claire Berryman, graduate student in nutritional sciences, Penn State.
"The walnut oil was particularly good at preserving the function of endothelial cells, which play an important role in cardiovascular health," said Berryman.
According to the researchers, walnuts contain alpha-linolenic acid, gamma-tocopherol and phytosterols, which may explain the positive effects of the walnut oil treatment.
"Implications of this finding could mean improved dietary strategies to fight heart disease," said Berryman.
"Our study indicates that simple dietary changes, such as incorporating walnuts and/or their oil in a heart healthy diet, may reduce the risk of heart disease," Kris-Etherton said.
The study will appear in the Journal of Nutrition.
