Table 3.
Summary of the soy protein research experiments
| Author (year) | Study | Intervention | Treatment duration | Outcome measurement | Effect on outcome |
|---|---|---|---|---|---|
| Horiuchi et al. (2000)55 | 85 PW/Japanese | Subjects with normal lumbar spine bone mineral density (L2–4 BMD) were investigated by questionnaire, and the calculated daily energy, protein, soy protein, and calcium intake were obtained. | L2–4 BMD | Positive correlation with soy protein intake (β= 0.225, P= 0.04) | |
| Urinary deoxypyridinoline | Negative correlation with soy protein intake (β= −0.08, P= 0.03) | ||||
| Zhang et al. (2005)56 | 24,403 PW (March 1, 1997–May 23, 2000)/Shanghai | Usual soy food intake | Biennial in-person | Risk factors of osteoporosis, the relative risks of fracture | After adjustment for age, major risk factors of osteoporosis, socioeconomic status, and other dietary factors, the relative risks (95% confidence intervals) of fracture were 1.00, 0.72 (0.62–0.83), 0.69 (0.59–0.80), 0.64 (0.55–0.76), and 0.63 (0.53–0.76) across quintiles of soy protein intake (P< 0.001 for trend). |
| Aubertin-Leheudre et al. (2007)57 | 18 Sarcopenic-obese women | 70 mg of isoflavones per day (44-mg diadzein, 16-mg glycitein, and 10-mg genestein) | 6 mo | FFM | The isoflavone group increased significantly appendicular (P= 0.034), leg (P= 0.016) FFM. |
| MMI | The isoflavone group increased significantly MMI (P= 0.037). | ||||
| Choquette et al. (2013)58 | 70 Overweight-toobese; body mass index, 32.2± 4.8 kg/m2; PW, 59± 5 years | (1) Placebo (n= 15), (2) isoflavones (n= 15), (3) exercise and placebo (n= 20), (4) exercise and isoflavones (n= 20) | 6 mo | Leg press, bench press | Exercise produced 49% and 23% increases, respectively, in leg press and bench press 1RM (P≤ 0.01). |
| Leg relative strength and muscle quality in the legs | Leg relative strength and muscle quality increased by more than 50% (both P< 0.01). | ||||
| Muscle mass index | Muscle mass index increased by 7% (P< 0.05) in both exercise groups only. | ||||
| Keshavarz et al. (2012)59 | 24 Overweight and obese female adults | A diet with soy milk or a diet with cow’s milk | 4 wk | Waist circumference | Waist circumference was reduced significantly following the soy milk period. |
| Llaneza et al. (2011)60 | 87 Healthy obese PW | Daily oral intake of a soy isoflavones extract (Fisiogen) containing 200 mg of Glycine max | 6 mo | Leptin | Mean serum leptin levels declined. |
| TNF-α | TNF-α levels declined. | ||||
| Van Nielen et al. (2014)61 | 15 PW with abdominal obesity | One diet, protein of mixed origin; the other diet, soy meat analogues and soy nuts containing 30 g/day soy protein. | 2–4 wk | Frequently sampled intravenous glucose tolerance test | The soy-protein diet resulted in greater insulin sensitivity. |
| Total cholesterol | Lower after the soy-protein diet compared to the mixed-protein diet. |
PW, postmenopausal women; BMD, bone mineral density; FFM, fat-free mass; MMI, muscle mass index; RM, repetition maximum; TNF-α, tumor necrosis factor-alpha.