Industrialization has increased the consumption of processed food and reduced fiber-rich food. These lifestyle changes have altered the gut microbiome by reducing fiber digesting and immune response regulating microbes. Thereby, increasing the risk of non-communicable diseases such as diabetes, heart and lung diseases, cancer, etc. The gut microbiome is highly personalized and has high inter-individual variability. Thus, gut microbiome alteration has remained challenging. This study was conducted as proof of principle to find whether dietary modifications can change the gut microbiome and determine their effect on clinical parameters such as BMI, blood glucose, cholesterol levels, and inflammatory markers.
Study details
This study was conducted in Canada and published in the Cell journal. The scientists performed a cross-over trial, where each individual acts as their own control. 30 healthy individuals participated in the study, where they were given a non-industrialized – fiber-rich, unprocessed – diet called “restore” diet for 3 weeks. After a 3-week washout period, they resumed their usual diet or vice-versa. The scientists observed that the restore diet reduced the diversity of the gut microbiome but increased the beneficial microbes. This could be due to the reduction of SCFAs (short-chain fatty acids) and gut pH, which killed the acid-sensitive bacterial population. SCFAs are mainly produced by gut microbes and play a crucial role in regulating host inflammatory response and intestine epithelial cell function. The restore diet also reduced inflammation and bile acid secretion. Hence, reduced bile-resistant species and increased inflammation-sensitive population. Moreover, due to the absence of dairy and meat byproducts, the bacterial populations feeding on these were also reduced. Despite the loss in diversity, they observed benefits in clinical parameters.
The restore diet changed 31 plasma metabolites, which are mainly produced by microbes and have positive implications on the risk markers for chronic diseases. With a slight reduction in BMI, the restore diet reduced fasting plasma total cholesterol, fasting glucose, C-reactive protein – a marker of systemic inflammation, and fecal calprotectin – a marker of gut inflammation as depicted in Table 1 and Figure 1. The insulin and triglyceride levels did not change, similar to previous studies on plant-rich diets.
Figure 1. Effect of the restore diet on non-communicable disease parameters. Created in BioRender, modified from the supplementary figure.
Table 1 – Effect of the restore diet on clinical parameters.
| Marker | Percentage change from baseline to day 21 (mean ± SD) | FDR adjusted p-value |
| BMI | -1.4 ± 1.9 % | 0.002 |
| Fasting plasma total cholesterol | -14.1 ± 11.2% | <0.001 |
| LDL cholesterol | -16.8 ± 15.8% | 0.003 |
| Non-HDL cholesterol | -15.2 ± 14.5% | 0.002 |
| HDL cholesterol | -11.3 ± 11.2% | 0.001 |
| Fasting plasma glucose | -6.3 ± 11.1% | <0.001 |
| C-reactive protein | -14 ± 58.3% | 0.014 |
| Fecal calprotectin | -21 ± 88.3% | 0.011 |
| Insulin sensitivity | 2.4 ± 6.4% | 0.036 |
Limitations and future scope
- There are various types of non-industrialized diets, and replicating them was challenging with food items available in Canada. Thus, the restore diet was an approximation, enriched in plant-based, fiber-rich food, and avoidance of highly processed food.
- The participants were mainly students and university employees due to proximity to campus and willingness to attend clinical visits. This could limit the applicability of these results to the general population.
- The sample size was relatively small (n=30). Although it was overcome partially by crossover design.
- The study did not determine the extent of microbiome change required to observe the clinical effect. Thus, more quantitative studies are needed for the future.
- Further studies can determine whether the consumption of these beneficial bacteria instead of a diet can provide these positive health implications.
Vinny Negi, Ph.D.
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