Diet, ageing and genetic factors in the pathogenesis of diverticular disease

Table 1 Summary of electrophysiology studies in diverticular disease (DD)

Study material	Treatment	Response	Study details	Reference
Colonic longitudinal smooth muscle	Relaxative cannabinoid agonists	Decreased relaxation in specimens vs controls	Study performed on diverticulitis specimens vs colorectal cancer controls	Guagnini et al[46]
Colonic longitudinal smooth muscle	Nitroprusside, relaxative agent	Decreased relaxation in specimens vs controls	Study performed on 10 DD patients vs 10 colorectal cancer controls	Golder et al[21]
Colonic circular smooth muscle	Contractionary, cholinergic stimuli	Decreased induction of contractionary waves in cases vs earlier data on "normal" patients	Material obtained from 12 patients, 10 of whom exhibited ‘abnormal responses’ Multiple samples from the same patient showed site specific differences	Huizinga et al[103]
Left-sided colonic smooth muscle	Nitric oxide, relaxative agent	Decreased relaxation in cases vs controls	Left-sided DD 9 patients, vs 16 left-sided colon cancer controls	Tomita et al[52]
Colonic longitudinal and circular muscle	Contractory acetylcholine	Increased contractionary response in DD cases vs controls	20 subjects with rectal tumours, 10 cases and 10 controls	Golder et al[51]
	Contractory tachykinin receptor antagonists	Higher active and resting stress in DD cases

Table 2 Observational studies of dietary fiber consumption and DD risk in man

Design	Findings	Comments	Reference
Case control study comparing dietary fiber intake in 100 (symptomatic) DD cases vs 80 age and sex matched controls	Dietary fiber intake significantly higher amongst controls	Study participants were patients hospitalized due to diverticulosis; again symptoms may have influenced their diet	Manousos et al[12]
Prevalence of DD assessed by barium enema in 189 non-vegetarian volunteers vs 55 vegetarians	Diverticular disease was significantly higher in the non- vegetarian group	"Asymptomatic" volunteers recruited prior to diagnosis and grouped based on dietary choices. A potential confounder is a possible causative effect for meat	Gear et al[104]
Case control study comparing dietary fiber intake in 40 (symptomatic) DD cases vs 80 age and sex matched controls	Dietary fiber intake significantly higher amongst controls	Dietary fiber intake was "estimated" by dieticians. Symptomatic DD patients were studied so the symptoms may have influenced their diet	Brodribb et al[62]
"Prospective" case control study. As part of the Health professionals follow up study, 43 881 US men aged 40-75 followed over 6 years, for self reported diagnoses	Dietary fiber intake significantly lower in cases RR = 0.63	The largest and potentially most informative study. Crucially, the participants were not clinically examined for DD prior to the study. So we cannot rule out effects of DD on dietary choices	Aldoori et al[63]
Case control study comparing dietary fiber intake between 86 right-sided DD cases and 106 controls	No relationship between DD and fiber consumption	Only study on right-sided DD, negative finding may indicate either a different etiology or perhaps right-sided DD just has fewer effects that might influence diet choice	Lin et al[64]

RR: Relative risk.