Published online Jul 26, 2022. doi: 10.12998/wjcc.v10.i21.7617
Peer-review started: March 17, 2022
First decision: April 25, 2022
Revised: April 26, 2022
Accepted: June 14, 2022
Article in press: June 14, 2022
Published online: July 26, 2022
Recently, we read with great interest an article reporting a relationship between dietary tryptophan and the risk of obesity and type 2 diabetes (T2D). However, baseline characteristics differed among tertiles of cumulative dietary tryptophan intake in that study, which may be a confounding factor for the relationship between dietary tryptophan and the risk of obesity and T2D.
Core Tip: A recent study showed that dietary tryptophan was associated with the risk of obesity and type 2 diabetes (T2D). However, baseline characteristics differed among tertiles of cumulative dietary tryptophan intake in that study, which may impact on the relationship between dietary tryptophan and the risk of obesity and T2D.
- Citation: Ren XH, Ye YW, He LP. Baseline differences may impact on relationship between dietary tryptophan and risk of obesity and type 2 diabetes. World J Clin Cases 2022; 10(21): 7617-7619
- URL: https://www.wjgnet.com/2307-8960/full/v10/i21/7617.htm
- DOI: https://dx.doi.org/10.12998/wjcc.v10.i21.7617
In recent years, the American Diabetes Association has started to strongly advocate the Mediterranean diet over other diets in patients with diabetes mellitus because of its beneficial effects on glycemic control and cardiovascular risk factors[1]. We read the article of Wang et al[2] with great interest. The results of their study showed that dietary tryptophan was associated with the risk of obesity and type 2 diabetes (T2D). These findings may provide valuable information to public health authorities for making novel dietary suggestions and preventing obesity and T2D more effectively. However, there are still issues worth discussing with the authors in this article.
The main problem of the study is that baseline characteristics were different among tertiles of cumulative dietary tryptophan intake. According to the baseline characteristics of the participants stratified by tertiles of cumulative dietary tryptophan intake (Table 1), body mass index (BMI), waist-hip ratio, systolic blood pressure, diastolic blood pressure, energy intake, high school education, prevalence of overweight, and prevalence of hypertension differed across the tertiles of cumulative dietary tryptophan intake. At baseline, people with obesity, overweight (BMI ≥ 24), and hypertension were more likely in the first tertile. Obesity is a well-known risk factor for T2D[3,4]. In this study, a negative correlation trend was found between BMI and tertiles of cumulative dietary tryptophan intake. Was increased diabetes risk a cause of obesity or insufficient tryptophan intake? Therefore, further research is needed to explore whether the increased risk of diabetes is due to obesity or insufficient tryptophan intake.
| Baseline variable | T1 (n = 2633) | T2 (n = 2642) | T3 (n = 2633) | P value |
| Age (yr) | 43.884 (14.624) | 43.196 (14.787) | 43.338 (15.187) | 0.207 |
| Female, n (%) | 1296 (49.221) | 1338 (50.643) | 1330 (50.513) | 0.521 |
| BMI (kg/m2) | 22.818 (2.966) | 22.344 (2.957) | 21.668 (2.669) | < 0.001 |
| WHR | 0.852 (0.066) | 0.847 (0.061) | 0.845 (0.061) | < 0.001 |
| PAL (MET-h/wk) | 306.102 (185.951) | 305.386 (183.797) | 314.724 (178.567) | 0.119 |
| Energy intake (kcal/d) | 2406.574 (730.597) | 2279.742 (631.699) | 2312.202 (619.281) | < 0.001 |
| Protein intake (g/d) | 75.854 (24.496) | 68.007 (21.007) | 63.132 (19.504) | < 0.001 |
| Fat intake (g/d) | 65.010 (37.716) | 71.561 (36.944) | 60.339 (32.443) | < 0.001 |
| Carbohydrate intake (g/d) | 376.755 (142.836) | 337.802 (113.510) | 375.947 (115.997) | < 0.001 |
| SBP (mmHg) | 120.945 (17.845) | 118.362 (17.904) | 116.824 (17.303) | < 0.001 |
| DBP (mmHg) | 78.296 (10.763) | 77.051 (11.277) | 75.871 (10.419) | < 0.001 |
| Baseline tryptophan consumption (mg/g protein) | 12.660 (0.972) | 13.812 (1.018) | 14.947 (1.216) | < 0.001 |
| Living in city, n (%) | 761 (28.902) | 942 (35.655) | 581 (22.066) | < 0.001 |
| Urban index | 51.952 (2.951) | 52.032 (2.732) | 51.797 (2.657) | 0.008 |
| Individual income (yuan) | 6019.137 (6773.845) | 6390.557 (5712.462) | 5325.567 (5445.487) | < 0.001 |
| High school education, n (%) | 457 (17.357) | 570 (21.575) | 347 (13.179) | < 0.001 |
| Smoking, n (%) | 886 (33.650) | 889 (33.649) | 853 (32.397) | 0.537 |
| Drinking, n (%) | 1008 (38.283) | 995 (37.661) | 903 (34.295) | 0.005 |
| Sleep time (h) | 8.085 (1.135) | 8.098 (1.179) | 8.215 (1.161) | < 0.001 |
| Prevalent diabetes, n (%) | 32 (1.215) | 38 (1.438) | 49 (1.861) | 0.148 |
| Prevalent obesity, n (%) | 162 (6.153) | 114 (4.315) | 69 (2.621) | < 0.001 |
| Prevalent overweight, n (%) | 540 (20.509) | 472 (17.865) | 274 (10.406) | < 0.001 |
| Prevalent hypertension, n (%) | 554 (21.041) | 478 (18.092) | 391 (14.850) | < 0.001 |
Overall, the differences in baseline characteristics among tertiles of cumulative dietary tryptophan intake may impact on the relationship between dietary tryptophan and the risk of obesity and T2D.
Provenance and peer review: Invited article; Externally peer reviewed.
Peer-review model: Single blind
Specialty type: Endocrinology and metabolism
Country/Territory of origin: China
Peer-review report’s scientific quality classification
Grade A (Excellent): 0
Grade B (Very good): 0
Grade C (Good): C, C
Grade D (Fair): 0
Grade E (Poor): 0
P-Reviewer: Bhattacharya S, India; Gica N, Romania A-Editor: Saha S, Australia S-Editor: Ma YJ L-Editor: Wang TQ P-Editor: Ma YJ
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