On 2013 Dec 04, Hilda Bastian commented:

This is a non-systematic review with unclear inclusion criteria, limited search strategy, and unclear methods for selection of studies. It includes reviews, primary studies and some animal studies. Important randomized trials in the area of dietary prevention of colorectal cancer have not been included. The conclusions of this paper are more positive about the potential for dietary prevention of colorectal cancer than conclusions from the National Cancer Institute.

Reviews of randomized trials not considered in this paper include: randomized trials have not shown a benefit of dietary or supplemented fiber (Asano T, 2002); and a combined analysis of 3 large randomized trials showing no clear effect of folate supplementation (Figueiredo JC, 2011).

The authors point out that their conclusions are largely based on non-randomized studies. Moorthy D, 2013 shows the extent to which results from epidemiological studies of nutrition can vary from randomized trial results. This blog post addresses aspects of the history of diet and the development of colorectal cancer.

On 2013 Dec 04, Hilda Bastian commented:

This is a non-systematic review with unclear inclusion criteria, limited search strategy, and unclear methods for selection of studies. It includes reviews, primary studies and some animal studies. Important randomized trials in the area of dietary prevention of colorectal cancer have not been included. The conclusions of this paper are more positive about the potential for dietary prevention of colorectal cancer than conclusions from the National Cancer Institute.

Reviews of randomized trials not considered in this paper include: randomized trials have not shown a benefit of dietary or supplemented fiber (Asano T, 2002); and a combined analysis of 3 large randomized trials showing no clear effect of folate supplementation (Figueiredo JC, 2011).

The authors point out that their conclusions are largely based on non-randomized studies. Moorthy D, 2013 shows the extent to which results from epidemiological studies of nutrition can vary from randomized trial results. This blog post addresses aspects of the history of diet and the development of colorectal cancer.