The necessity of enzymatically hydrolyzing walnut protein to exert antihypertensive activity based on in vitro simulated digestion and in vivo verification.

Since not all proteins are suitable for preparing bioactive peptides by enzymatic degradation, the purpose of this study is to evaluate the necessity of walnut protein (WP) enzymolysis to exert its potential antihypertensive activity. Five proteases were used to hydrolyze WP to produce WP hydrolysate (WPH) enzymatically. The angiotensin-I-converting enzyme (ACE) inhibitory activity of WP and WPH before and after simulated digestion in vitro was measured, and the antihypertensive effect was evaluated in vivo. The results showed that after simulated digestion in vitro, the ACE inhibitory activity of WP digests (44.85%) was not significantly different from that of WPH digests (p > 0.05). In vivo experimental results showed that both WP and WPH had significant blood pressure lowering effects in the acute and long-term administrative experiments. The mechanism of its antihypertensive activities was regulating the balance of the renin-angiotensin-aldosterone system and the kallikrein-kinin system by inhibiting ACE activities in tissues and regulating the level of endothelium-derived vasoconstrictor factors and relaxing factors in serum. It seems unnecessary to carry out enzymatic hydrolysis to produce walnut peptides with antihypertensive activity.

Antidiabetic effects of water-soluble Korean pine nut protein on type 2 diabetic mice.

Korean pine nut protein (PNP) has a variety of biological activities, which are good for human health, but its ability to preventing diabetes has not been reported. This study evaluated the effects of water-soluble proteins of Korean pine nut obtained from a dilute alkali extract on carbohydrate metabolism of type 2 diabetic mice on a model of diabetes induced using a high fat diet combined with streptozotocin. The results showed that the hypoglycemic effect of PNP at a middle dose was the most significant, which was 38.7% lower than that of control. The extract significantly improved the oral glucose tolerance and liver indexes, increased the activity of the carbohydrate metabolism enzymes, and regulated the expression of the function of key genes for carbohydrate metabolism. It had a positive effect on both insulin resistance and glycolytic/gluconeogenesis signaling. In conclusion, PNP can regulate fasting blood glucose, improve insulin resistance, correct the glucose metabolism disorder in diabetic mice, and have a positive regulatory role. As the functional food, it has the potential to be beneficial in the treatment of type 2 diabetes mellitus as a new hypoglycemic functional food.

Walnut oral immunotherapy for desensitisation of walnut and additional tree nut allergies (Nut CRACKER): a single-centre, prospective cohort study.

BACKGROUND: The safety and efficacy of oral immunotherapy for tree nut allergy has not been demonstrated to date, and its effectiveness is complicated by the high prevalence of co-allergies to several nuts. This study aimed to investigate the use of walnut oral immunotherapy in the desensitisation of walnut and additional tree nuts in patients who are co-allergic to several nuts. METHODS: In a single-centre, prospective cohort study (the Nut Co-Reactivity ACquiring Knowledge for Elimination Recommendations study) at the Institute of Allergy, Immunology, and Paediatric Pulmonology at the Yitzhak Shamir Medical Centre, we recruited patients aged 4 years or older who were allergic to walnut, with or without co-allergy to pecan, hazelnut, and cashew. The diagnosis of each food allergy was based on a positive skin prick test or specific serum IgE (≥0·35 kUA/L) to the corresponding nut together with a positive oral food challenge, unless an immediate (within 2 h of exposure) reaction in the past year had been documented. Patients with uncontrolled asthma or a medical contraindication to receive adrenaline were excluded. Patients were assigned to walnut oral immunotherapy or the control group (observation and strict dietary exclusion) on the basis of the order of presentation to the clinic. Oral immunotherapy began with a 4-day dose-escalation phase to establish the single highest tolerated dose, which was consumed daily at home for 24 days; subsequent monthly dose escalations were repeated until 4000 mg walnut protein was achieved. Patients who were desensitised to walnut continued to consume 1200 mg walnut protein daily for 6 months as maintenance. The primary outcome was walnut desensitisation (passing an oral food challenge with 4000 mg of walnut protein) at the end of the study, analysed by intention to treat. In patients who were co-allergic to pecan, hazelnut, and cashew, the proportion who achieved cross-desensitisation to these nuts in addition to walnut desensitisation was examined. FINDINGS: 73 patients with a walnut allergy were enrolled between May 15, 2016, and Jan 14, 2018. 49 (89%) of 55 patients in the oral immunotherapy group were desensitised to walnut compared with none of 18 patients in the control group (odds ratio 9·2, 95% CI 4·3-19·5; p<0·0001). Following walnut desensitisation, all patients who were co-allergic to pecan (n=46) were also desensitised to pecan. Additionally, 18 (60%) of 30 patients who were co-allergic to hazelnut or cashew, and 14 (93%) of 15 patients who were co-allergic to hazelnut alone, were either fully desensitised or responded to treatment. 47 (85%) of 55 patients had an adverse reaction (mostly grade 1 or 2) during up-dosing in the clinic; eight patients required intramuscular epinephrine in response to a dose at home. Of 45 patients who had follow-up data for the maintenance phase, all maintained walnut desensitisation and one patient required epinephrine during this period. INTERPRETATION: Walnut oral immunotherapy can induce desensitisation to walnut as well as cross-desensitisation to pecan and hazelnut in patients who have tree nut co-allergies, with a reasonable safety profile. A low daily dose of the allergen maintains desensitisation. FUNDING: None.