Generated Summary
The study is a series of systematic reviews and meta-analyses of prospective studies and randomized controlled trials published from database inception to April 30, 2017, and Feb 28, 2018, respectively. The main objective was to quantitatively assess the predictive potential of various carbohydrate quality markers, pinpoint the most useful markers, and establish an evidence base for dietary fiber intake recommendations. The research encompassed an extensive review of databases to identify relevant studies that reported on indicators of carbohydrate quality and health outcomes. The data extraction and bias assessment were conducted independently, and the robustness of the pooled estimates was considered using random-effects models. Sensitivity analyses, meta-regression, dose-response testing, and subgroup analyses were performed to enhance the reliability of the findings. The GRADE approach was used to assess the quality of the evidence.
Key Findings & Statistics
- Observational data showed a 15-30% reduction in all-cause and cardiovascular-related mortality.
- Incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer were also reduced when comparing the highest dietary fiber consumers with the lowest consumers.
- Clinical trials revealed significantly lower body weight, systolic blood pressure, and total cholesterol in those with higher dietary fiber intake.
- The most significant risk reduction was observed when daily intake of dietary fiber was between 25 g and 29 g.
- Dose-response curves suggested higher intakes of dietary fiber could further protect against cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer.
- Similar benefits were observed for whole grain intake.
- The certainty of evidence was graded as moderate for dietary fiber, low to moderate for whole grains, and low to very low for dietary glycaemic index and glycaemic load.
Other Important Findings
- Findings from prospective studies and clinical trials associated with relatively high intakes of dietary fiber and whole grains were complementary.
- Observational data comparing diets characterized by low versus higher glycaemic index or load showed smaller or no risk reductions.
- Data relating to other dietary exposures were scarce.
Limitations Noted in the Document
- The findings primarily focus on risk reduction in the general population rather than specific chronic disease groups.
- The data regarding other dietary exposures were limited, which may have affected the overall conclusions.
Conclusion
The study provides robust evidence supporting the health benefits of high dietary fiber and whole grain intake. The dose-response curves showed that increasing fiber intake could lead to greater protection against various diseases, including cardiovascular diseases, type 2 diabetes, and certain cancers. The study results emphasize the importance of promoting dietary fiber and whole grains in public health recommendations. These findings reinforce the need for more research focusing on specific dietary exposures to better understand their impact on health outcomes. The current evidence underscores the potential for dietary interventions, particularly those emphasizing increased fiber intake, to significantly improve public health.
IFFS Team Summary
- See entry in High Protein Low Carb vs Whole Grain section