Effects of energy-restricted diets with or without nuts on weight, body composition and glycaemic control in adults: a scoping review
Energy-restricted (ER) diets promote weight loss and improve body composition and glycaemic control. Nut consumption also improves these parameters. However, less is known about the combined benefit of these two strategies. This scoping review implemented a systematic search of Medline, Embase and Scopus to identify randomised controlled trials evaluating the effect of ER diets with or without nuts on body mass, body composition and glycaemic control in adults. After reviewing titles and abstracts, twenty-nine full-text articles were screened, resulting in seven studies reported in eight papers that met the inclusion criteria. Energy restriction was achieved by prescribing a set energy target or reducing intake by 1000-4200 kJ from daily energy requirements. Interventions ranged from 4 to 52 weeks in duration and contained 42-84 g/d of almonds, peanuts, pistachios or walnuts. While all studies reported that energy restriction resulted in significant weight loss, the addition of nuts to ER diets demonstrated significantly greater weight loss in only approximately half of the included studies (4/7 studies). There was limited evidence to support additional benefits from nuts for body composition measures or glycaemic control. Although improvements in weight loss and glycaemia were not consistent when nuts were included in ER diets, no study revealed an adverse effect of nut consumption on health outcomes. Future studies could explore the effect of consuming different types and amounts of nuts, combined with various levels of energy restriction on weight, body composition and glycaemic control. https://doi.org/10.1017/S0954422424000106
Tree nut phytochemicals: composition; antioxidant capacity; bioactivity; impact factors. A systematic review of almonds; Brazils; cashews; hazelnuts; macadamias; pecans; pine nuts; pistachios and walnuts
Tree nuts contain an array of phytochemicals including carotenoids; phenolic acids; phytosterols and polyphenolic compounds such as flavonoids; proanthocyanidins (PAC) and stilbenes; all of which are included in nutrient databases; as well as phytates; sphingolipids; alkylphenols and lignans; which are not. The phytochemical content of tree nuts can vary considerably by nut type; genotype; pre- and post-harvest conditions; as well as storage conditions. Genotype affects phenolic acids; flavonoids; stilbenes and phytosterols; but data are lacking for many other phytochemical classes. During the roasting process; tree nut isoflavones; flavanols and flavonols were found to be more resistant to heat than the anthocyanins; PAC and trans-resveratrol. The choice of solvents used for extracting polyphenols and phytosterols significantly affects their quantification; and studies validating these methods for tree nut phytochemicals are lacking. The phytochemicals found in tree nuts have been associated with antioxidant; anti-inflammatory; anti-proliferative; antiviral; chemopreventive and hypocholesterolaemic actions; all of which are known to affect the initiation and progression of several pathogenic processes. While tree nut phytochemicals are bioaccessible and bioavailable in humans; the number of intervention trials conducted to date is limited. The objectives of the present review are to summarise tree nut: (1) phytochemicals; (2) phytochemical content included in nutrient databases and current publications; (3) phytochemicals affected by pre- and post-harvest conditions and analytical methodology; and (4) bioactivity and health benefits in humans.