Walnuts pack the biggest punch when it comes to healthy nuts

Walnuts have been crowned king of nuts when it comes to health benefits, according to scientists.

Researchers studied a range of nuts, including almond, peanut and cashew, to assess their levels of polyphenol - a type of antioxidant - the first time a large number of samples of both raw and roasted nuts has been analysed for total polyphenol content.

The team, from the University of Scranton, Pennsylvania, published their findings in the latest issue of the Royal Society of Chemistry journal Food and Function.

Professor Joe Vinson's study evaluated nine types of raw and roasted nuts and two types of peanut butter to assess the total amount of polyphenols found in each, as well as the polyphenols' expected ability to inhibit oxidation of lower density lipoproteins, often referred to as "bad cholesterol". His study found that walnuts had the highest levels of antioxidants and that the quality, or potency, of antioxidants present in walnuts was highest among the nuts. 

Dr Vinson said: "Walnuts rank above Brazil nuts, pistachios, pecans, peanuts, almonds, macadamias, cashews and hazelnuts." His study also found that total polyphenols in peanut butter were considerably lower than roasted peanuts, but the difference was not statistically signi?cant. 

Dr. Vinson's study also found that nuts account for around eight percent of the daily antioxidants in the average person's diet. "The total nut consumption (tree nuts and peanuts) in the United States was estimated at 12.9 grams per day, which is similar to the 2007 European Union consumption of 11.1 grams per day," he said. "Peanuts comprised 65 percent of the nut consumption in the United States and 45 percent in the European Union."

He concluded that the relative low consumption of nuts in the daily diet might stem from many people being unaware that nuts are such a healthful food. Others may be concerned about gaining weight from a food so high in fat and calories. But he points out that nuts contain healthful polyunsaturated and monosaturated fats rather than artery-clogging saturated fat.

The research concluded: "Nuts are high in fiber, low in saturated fats, high in beneficial unsaturated fats, and very high in antioxidants. Nuts are a nutritious snack and food additive providing both nutrients and bioactive antioxidants which provide significant health benefits to the consumer."

Advising consumers to keep the portion size small, Dr Vinson said it takes only about seven walnuts a day, for instance, to get the potential health benefits uncovered in previous studies.

References

Nuts, especially walnuts, have both antioxidant quantity and efficacy and exhibit significant potential health benefits
Joe A. Vinson and Yuxing Cai
Food and Function., 2012
DOI: 10.1039/C2FO10152a