Moving back to animal fats in our diet will help fix a lot of what ails us as this excerpt explains:
"While fat per se is not negatively associated with longevity, it is positively associated with digestion and gut performance. Low fat high carbohydrate diets of a high glycemic index have been associated with symptomatic gall bladder disease (Tsai et al. 2005) likely due to reduced cycling of cholesterol through bile salt release. Although fat or oil are often stated as affecting gastrooesophagial reflux disease, a systematic review of the literature failed to find an effect of fat consumption (Dent et al. 2005). In addition, fat has a unique ability to stimulate colonic contraction, not found for carbohydrate or protein, and these contractions are essential to the voiding of faeces (Wright et al. 1980). Indeed, remedies for constipation before the Second World War recommended, in addition to ‘roughage’, water and the avoidance of diuretics, the consumption of fat such as bacon fat, butter, or olive oil, especially if the faeces was small and dry (Hutchison 1936), and for spastic colon no fibre and large amounts of the above listed fat was recommended. This is not a recommendation that is in any current medical guideline. Yet several pieces of evidence show that it is valid. First, infants take in no fibre, so amount of fibre is not a variable. Animal fats in the formula result in stools that are softer, larger, and that are easier to pass than plant fats (Forsyth et al. 1999), and babies also grow better when the source of the fat is from animal rather than plant sources (López-López et al. 2001). The exact reasons for these effects are not known, but these effects are thought to be due partly to the characteristic stereoisomeric structure of animal fats compared with plant fats (Hunter 2001), and the presence of long-chain PUFA. Second, in a study of a large number of Swiss citizens, the small percentage of individuals with great difficulty in passing faeces were statistically more likely to have a high fibre diet than a low fibre diet (Curtin et al. 1998). Although individuals on a high fat diet were less likely to report difficulty in passing faeces this was not statistically significant. Third, animal fat also contains a substantial proportion of stearic acid. Up to 20% of stearic acid, depending on the stereoisomeric location of the FA, is not absorbed by the enterocytes compared with 0–2% for other FA (Bracco 1994). The unabsorbed stearic acid will crystallise in the lumen of the gut as the pH increases and be excreted as a calcium soap (Owen et al. 1995). This reduces the energy of the diet, and changes the consistency and increases the mass of the faeces (Dougherty et al. 1995). This is not to argue that dietary fibre is unimportant, rather that dietary fibre is often not sufficient to cure constipation and other ailments of the colon and rectum. Constipation underlies many of the diseases of the bowel, and it is long known to be a precursor to diverticulitis, varicose veins, and haemorrhoids, among other disorders (Burkitt 1973; Cleave 1974). Colorectal cancer is related to diet quality, risk is reduced through the consumption of vegetables, fruit and resistant starch (Macquart-Moulin et al. 1987; Steinmetz and Potter 1991; Van Munster et al. 1994; Archer et al. 1998; Topping and Clifton 2001; Mathers et al. 2012), and fat consumption has not been shown to be linked to its occurrence in large meta-analyses (Nelson et al. 1999; Liu et al. 2011). As an aside, colorectal cancer has been linked to red meat, preserved meat and beer consumption, which may implicate methods of preparation and preservation of food involving known factors such as nitrosamines and heterocyclic amines (McMichael et al. 1979; Potter 1999; Aune et al. 2013; Egeberg et al. 2013)."