Table 3.
Summary of in vivo studies and their characteristics in the context of nut consumption and type 2 diabetes (T2D)-related outcomes.
| First Author (Year) [Reference] | Nut (Study Length) | Animal Model Used | Control | Intervention | Glucose and Insulin Metabolism Effects | Other Outcomes |
|---|---|---|---|---|---|---|
| Bilbis, L.S.; et al. (2002) [25] | Aqueous extract of peanut (21 days) | Alloxan-induced diabetic rats (n = 12) and non-diabetic rats (n = 12), divided into 3 equal groups | Non-diabetic with unrestricted standard diet and: (a) water ad libitum; (b) unrestricted access to drinking water and 2 mL of the extract 3 times/day; or (c) free access to the extract as the only drinking water. | Diabetic controls: treated as (a), (b) or (c) | The extract (alone or plus water) decreased FBG in both normal and alloxan-induced diabetic rats. | Significant decrease in serum TG, TC, HDL-C and LDL-C in both normal and alloxan-induced diabetic rats. |
| Fukuda, T.; et al. (2004) [26] | Polyphenol-rich walnut extract (PWE) (4 weeks) | db/db (n = 15) and C57BL/KsJ-db/db (n = 6) mice | Control db/db mice (n = 8) and C57BL/KsJ-db/+ m mice (n = 6, used for the blank group) were given water. | Experimental db/db mice (n = 7) received oral PWE (200 mg/kg BW) | Significant decrease in the level of urinary 8-hydroxy-2′-deoxyguanosin (in vivo marker of oxidative stress) in PWE-fed mice | Serum TG level was improved after PWE administration |
| Ramesh, B.; et al. (2006) [27] | Peanut oil (42 days) | Normal (n = 12) and STZ-diabetes induced (n = 18) Wistar rats | G1: Normal rats G3: Diabetic rats | G2: Normal rats + peanut oil diet (2%) G4: Diabetic rats + peanut oil diet (2%) G5: Diabetic rats + GLI (600 µg/kg BW) | Diabetic rats fed with peanut oil significantly reduce glucose, HbA1C, and G6Pase and FBP activities | Diabetic rats fed with peanut oil showed a small but significant reduction in TC, VLDL-C, LDL-C and TG and an increase in HDL-C. |
| Vassiliou, E.K.; et al. (2009) [41] | Peanut oil (21 days) | Male KKAy (n = 24) mice | KKA y mice fed with normal diet (11.4% fat) | Diabetic KKAy + HFD. Diabetic KKAy + HFD with peanut oil (0.70 mL/day). HFD is 58% fat. | Diabetic mice administered peanut oil had lower glucose levels than animals administered HFD alone. | |
| Choi, Y.; et al. (2016) [29] | Walnuts (20 weeks) | Male C57BL/6J mice (≥6 mice/group) | Regular rodent chow | HFD (45% energy-derived) with or without walnuts (21.5% energy-derived) | Glucose and insulin resistance tended to improve with walnut supplementation. | Walnut supplementation did not change the HFD-induced increase in BW or VFM. However, dietary walnuts significantly decreased the amounts of hepatic TG observed in HFD-fed mice. |
| Adewale, O.F.; et al. (2016) [42] | Peanut oil Palm oil (3 weeks) | Normal (n = 12) and alloxan-induced diabetic Wistar rats (n = 36) | Non-diabetic | Diabetic non-supplemented. Diabetic supplemented with PeO or PaO (200 mg/kg/day) | Significant reduction in blood glucose of supplemented groups (PeO + PaO) compared to the diabetic non-supplemented group. | Plasma Vitamins C and E and albumin levels were significantly increased in the supplemented groups versus the diabetic non-supplemented group. |
BW, body weight; FBG, fasting blood glucose; FBP, fructose-1,6-bisphosphatase; G6Pase, glucose 6-phosphatase; GLI, glibenclamide; HDL-C, high-density lipoprotein cholesterol; HFD, high-fat diet; LDL-C, low-density lipoprotein cholesterol; PaO, palm oil; PeO, peanut oil; PWE, polyphenol-rich walnut extract; STZ, streptozotocin; T2D, type 2 diabetes; TC, total cholesterol; TF, tissue factor; TG, triglycerides; VFM, visceral fat mass; VLDL-C, very low-density lipoprotein.