Walnuts (Juglans regia) Chemical Composition and Research in Human Health

Abstract

Walnuts are among the most widely consumed commercially grown tree nuts in the world. Many health benefits have been claimed for the consumption of these, including reduced risk of cardiovascular disease, coronary heart disease, type II diabetes treatment, and prevention and treatment of certain cancers, and the lessening of symptoms attributed to age-related and other neurological disorders. The health-promoting benefits of walnut consumption are ascribed to its fatty acid profile, which is rich in polyunsaturated fatty acids with a particularly high ω3:ω6 ratio-the highest among all the tree nuts. The content of polyphenols and other phytochemicals in walnuts, with their claimed cytotoxic properties, also make them an attractive candidate for research for the prevention of free radical-induced nucleic acid damage. Research of walnut consumption in humans and animals employing a range of data sets and statistical methods suggest that walnuts may be considered a safe potential nutraceutical or possibly pharmaceutical substance. Nevertheless, few reviews of scientific research on the proposed benefits of these nuts exist, in spite of the numerous claims attributed to them in the lay media. This brief review article attempts to disseminate much of the information surrounding walnut consumption, and human health benefits, to other scientists and the interested general reader.

Kernel oil content and oil composition in walnut (Juglans regia L.) accessions from north‐eastern Italy

“…It is a valuable lipid food source; indeed the oil content, ranging in commercial walnut varieties from 620 to 740 g kg −1 kernel, is the predominant component of this nut crop . Walnut oil is naturally rich in polyunsaturated fatty acids (PUFAs), mainly linoleic (55–70%) and linolenic (10–18%) acids, and is consequently poor in monounsaturated fatty acids (MUFAs), represented by oleic acid (10–20%), and in saturated fatty acids (SFAs) . Walnuts are mainly consumed as fruit, and their nutritional qualities and use depend mainly on their oil fatty acid profile.…”

“…The development of alternative walnut oil feedstocks with improved functionality while maintaining nutritional quality has therefore become a priority for the food industry. The specific goal in walnut breeding could be improving the oxidative stability through reduction of PUFAs and relative increase of MUFAs . The objective of improved stability could be reached by raising the SFA content, but that can have adverse effects on human health due to the increase of low‐density lipoprotein (LDL) in blood caused by high palmitic acid (C16:0) consumption .…”

“…[2][3][4] Walnut oil is naturally rich in polyunsaturated fatty acids (PUFAs), mainly linoleic (55-70%) and linolenic (10-18%) acids, and is consequently poor in monounsaturated fatty acids (MUFAs), represented by oleic acid (10-20%), and in saturated fatty acids (SFAs). 2,[4][5][6] Walnuts are mainly consumed as fruit, and their nutritional qualities and use depend mainly on their oil fatty acid profile. Walnut oil is excellent if used fresh for edible purposes, because it is rich in the so-called -3 and -6 fatty acids that are essential for the human diet.…”

Effects of Walnut Consumption on Colon Carcinogenesis and Microbial Community Structure

“…Among all the nuts from the tree nut family, walnuts (Juglans regia) are the most enriched in PUFAs, with the highest ratio of omega-3:omega-6 (1:4.2). Walnuts also contain high levels of g-tocopherol, a form of vitamin E with proven anticancer benefit (9,12). A number of studies have identified beneficial effects of walnut consumption in a variety of diseases, including heart disease, diabetes, neurologic disorders, and cancer (9).…”

“…Nuts contain a large variety of beneficial bioactive components, including monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) and contain only low amounts of saturated fatty acids (SFA), as well as a number of phytochemicals (i.e., phenolic antioxidants), dietary fiber, and minerals (9,10). PUFAs, including omega-3 fatty acids, reduce inflammation and have also been shown to lower polyp burden in animal models of colon cancer (11).…”