Consuming nuts may have advantages over other snack foods for health and body-weight regulation. Suggested mechanisms include increased satiety and lower glycaemia. We used an acute randomised crossover trial to assess glycaemic and appetite responses to consuming two isocaloric snacks (providing 10% of participants’ total energy requirements or 1030 kJ (equivalent to 42.5 g almonds), whichever provided greater energy): raw almonds and sweet biscuits among 100 participants with available data (25 males and 75 females) following 106 being randomised. Two hours after consuming a standardised breakfast, participants consumed the snack food. Finger-prick blood samples measuring blood glucose and subjective appetite ratings using visual analogue scales were taken at baseline and at 15 or 30 min intervals after consumption. Two hours after snack consumption, an ad libitum lunch was offered to participants and consumption was recorded. Participants also recorded food intake for the remainder of the day. The mean area under the blood glucose response curve was statistically and practically significantly lower for almonds than biscuits (mean (95% CI) difference: 53 mmol/L.min (45, 61), p < 0.001). Only the composite appetite score at 90 min was higher in the almond treatment compared to the biscuit treatment (45.7 mm vs. 42.4 mm, p = 0.035 without adjustment for multiple comparisons). There was no evidence of differences between the snacks for all other appetite ratings or for energy intake at the ad libitum lunch. However, mean energy intakes following snack consumption were significantly lower, both statistically and in practical terms, for the almond treatment compared to the biscuit (mean (95% CI) diff: 638 kJ (44, 1233), p = 0.035). Replacing popular snacks with almonds may have advantages in terms of glycaemia and energy balance.

Dietary guidelines recommend consuming 30 g of nuts per day to reduce the risk of chronic disease. A ‘handful’ is commonly used to guide consumers. Research is lacking on how this translates into actual gram amounts. This study quantified the grams of nuts represented by different portion size measures, including a ‘handful’ and ‘30 g serving’ among 120 participants. Each participant was randomised to a sequence where they received three of six different nut types (from almonds, cashews, hazelnuts, macadamias, peanuts, and walnuts) and were instructed to take a: ‘usual serving’, ‘handful’, ‘small handful’, ‘large handful’, and ‘30 g serving’ of each. Combining all nut types, the median ‘handful’ was 36.3 g, compared to 28.7 g for the estimated ‘30 g serving’ and 24.8 for the ‘usual serving’. The ‘large handful’ was approximately double the ‘handful’ (61.3 g), whereas the ‘small handful’ was about half (16.7 g). Eighty-three percent of portions chosen were at least 80% of the recommended 30 g intake when participants were asked to take a ‘handful’, compared to 63% for the ‘30 g serving’. It appears a ‘handful’ can be used as a practical tool to guide recommended nut intakes, and increases the amount selected compared to instructions to take a ‘30 g serving’.

Despite being rich sources of monounsaturated fat and a number of vitamins, minerals, and phytonutrients, hazelnuts have received less attention than some other nut types. A qualitative systematic review was carried out to determine the effects of hazelnut consumption on acceptance and markers of cardiometabolic health, including blood lipids and lipoproteins, apolipoproteins A1 and B100, body weight and composition, blood pressure, glycemia, antioxidant status, oxidative stress, inflammation, and endothelial function. In total, 22 intervention studies (25 publications) met our inclusion criteria. The findings indicate some improvements in cardiometabolic risk factors; however, limitations in study design mean interpretation is problematic. The inclusion of hazelnuts in the diet did not adversely affect body weight and composition. Acceptance of hazelnuts remained stable over time confirming nut consumption guidelines are feasible and sustainable. Future studies using more robust study designs in a variety of populations are required to draw more definitive conclusions on the health benefits of hazelnut consumption.

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