Fred K. Tabung

Considering the Value of Dietary Assessment Data in Informing Nutrition-Related Health Policy

Dietary assessment has long been known to be challenged by measurement error. A substantial amount of literature on methods for determining the effects of error on causal inference has accumulated over the past decades. These methods have unrealized potential for improving the validity of data collected for research studies and national nutritional surveillance, primarily through the NHANES. Recently, the validity of dietary data has been called into question. Arguments against using dietary data to assess diet-health relations or to inform the nutrition policy debate are subject to flaws that fall into 2 broad areas: 1) ignorance or misunderstanding of methodologic issues; and 2) faulty logic in drawing inferences. Nine specific issues are identified in these arguments, indicating insufficient grasp of the methods used for assessing diet and designing nutritional epidemiologic studies. These include a narrow operationalization of validity, failure to properly account for sources of error, and large, unsubstantiated jumps to policy implications. Recent attacks on the inadequacy of 24-h recall-derived data from the NHANES are uninformative regarding effects on estimating risk of health outcomes and on inferences to inform the diet-related health policy debate. Despite errors, for many purposes and in many contexts, these dietary data have proven to be useful in addressing important research and policy questions. Similarly, structured instruments, such as the food frequency questionnaire, which is the mainstay of epidemiologic literature, can provide useful data when errors are measured and considered in analyses.

Association between dietary inflammatory potential and breast cancer incidence and death: results from the Women's Health Initiative

Background:Diet modulates inflammation and inflammatory markers have been associated with cancer outcomes. In the Women’s Health Initiative, we investigated associations between a dietary inflammatory index (DII) and invasive breast cancer incidence and death.Methods:The DII was calculated from a baseline food frequency questionnaire in 122 788 postmenopausal women, enrolled from 1993 to 1998 with no prior cancer, and followed until 29 August 2014. With median follow-up of 16.02 years, there were 7495 breast cancer cases and 667 breast cancer deaths. We used Cox regression to estimate multivariable-adjusted hazards ratios (HRs) and 95% confidence intervals (95% CIs) by DII quintiles (Q) for incidence of overall breast cancer, breast cancer subtypes, and deaths from breast cancer. The lowest quintile (representing the most anti-inflammatory diet) was the reference.Results:The DII was not associated with incidence of overall breast cancer (HRQ5vsQ1, 0.99; 95% CI, 0.91–1.07; Ptrend=0.83 for overall breast cancer). In a full cohort analysis, a higher risk of death from breast cancer was associated with consumption of more pro-inflammatory diets at baseline, after controlling for multiple potential confounders (HRQ5vsQ1, 1.33; 95% CI, 1.01–1.76; Ptrend=0.03).Conclusions:Future studies are needed to examine the inflammatory potential of post-diagnosis diet given the suggestion from the current study that dietary inflammatory potential before diagnosis is related to breast cancer death.

Intake of grains and dietary fiber and prostate cancer aggressiveness by race.

Purpose. To examine the associations among intake of refined grains, whole grains and dietary fiber and aggressiveness of prostate cancer in African Americans (AA, n = 930) and European Americans (EA, n = 993) in a population-based, case-only study (The North Carolina-Louisiana Prostate Cancer Project, PCaP). Methods. Prostate cancer aggressiveness was categorized as high, intermediate or low based on Gleason grade, PSA level and clinical stage. Dietary intake was assessed utilizing the NCI Diet History Questionnaire. Logistic regression (comparing high to intermediate/low aggressive cancers) and polytomous regression with adjustment for potential confounders were used to determine odds of high prostate cancer aggressiveness with intake of refined grains, whole grains and dietary fiber from all sources. Results. An inverse association with aggressive prostate cancer was observed in the 2nd and 3rd tertiles of total fiber intake (OR = 0.70; 95% CI, 0.50–0.97 and OR = 0.61; 95% CI, 0.40–0.93, resp.) as compared to the lowest tertile of intake. In the race-stratified analyses, inverse associations were observed in the 3rd tertile of total fiber intake for EA (OR = 0.44; 95% CI, 0.23–0.87) and the 2nd tertile of intake for AA (OR = 0.57; 95% CI, 0.35–0.95). Conclusions. Dietary fiber intake was inversely associated with aggressive prostate cancer among both AA and EA men.

Longitudinal changes in the dietary inflammatory index: an assessment of the inflammatory potential of diet over time in postmenopausal women

Background/Objectives:The dietary inflammatory index (DII) measured at one time point is associated with risk of several chronic diseases, but disease risk may change with longitudinal changes in DII scores. Data are lacking regarding changes in DII scores over time; therefore, we assessed changes in the DII in the Women’s Health Initiative (WHI).Subjects/Methods:DII scores were calculated using data from repeated food frequency questionnaires in the WHI Observational Study (OS; n=76 671) at baseline and year 3, and the WHI Dietary Modification trial (DM; n=48482) at three time points. Lower DII scores represent more anti-inflammatory diets. We used generalized estimating equations to compare mean changes in DII over time, adjusting for multiple comparisons, and multivariable-adjusted linear regression analyses to determine predictors of DII change.Results:In the OS, mean DII decreased modestly from −1.14 at baseline to −1.50 at year 3. In the DM, DII was −1.32 in year 1, −1.60 in year 3 and −1.48 in year 6 in the intervention arm and was −0.65 in year 1, −0.94 in year 3 and −0.96 in year 6 in the control arm. These changes were modified by body mass index, education and race/ethnicity. A prediction model explained 22% of the variance in the change in DII scores in the OS.Conclusions:In this prospective investigation of postmenopausal women, reported dietary inflammatory potential decreased modestly over time. Largest reductions were observed in normal-weight, highly educated women. Future research is warranted to examine whether reductions in DII are associated with decreased chronic disease risk.

Association of Dietary Inflammatory Potential With Colorectal Cancer Risk in Men and Women

Importance Inflammation is important in colorectal cancer development. Diet modulates inflammation and may thus be a crucial modifiable factor in colorectal cancer prevention. Objective To examine whether proinflammatory diets are associated with increased colorectal cancer risk by using an empirical dietary inflammatory pattern (EDIP) score based on a weighted sum of 18 food groups that characterizes dietary inflammatory potential based on circulating levels of inflammation biomarkers. Design, Settings, and Participants Cohort study of 46 804 men (Health Professionals Follow-up Study: 1986-2012) and 74 246 women (Nurses’ Health Study: 1984-2012) followed for 26 years to examine associations between EDIP scores and colorectal cancer risk using Cox regression. We also examined associations in categories of alcohol intake and body weight. Data analysis began January 17, 2017, and was completed August 9, 2017. Exposures EDIP scores calculated from food frequency questionnaires administered every 4 years. Main Outcomes and Measures Incident colorectal cancer. Results We documented 2699 incident colorectal cancer cases over 2 571 831 person-years of follow-up. Compared with participants in the lowest EDIP quintile (Q) who had a colorectal cancer incidence rate (per 100 000 person-years) of 113 (men) and 80 (women), those in the highest Q had an incidence rate of 151 (men) and 92 (women), leading to an unadjusted rate difference of 38 and 12 more colorectal cancer cases, respectively, among those consuming highly proinflammatory diets. Comparing participants in the highest vs lowest EDIP Qs in multivariable-adjusted analyses, higher EDIP scores were associated with 44% (men: hazard ratio [HR], 1.44; 95% CI, 1.19-1.74; P < .001 for trend), 22% (women: HR, 1.22; 95% CI, 1.02-1.45; P = .007 for trend), and 32% (men and women: pooled HR, 1.32; 95% CI, 1.12-1.55; P < .001 for trend) higher risk of developing colorectal cancer. In both men and women, associations were observed in all anatomic subsites except for the rectum in women. In subgroups (P ⩽ .02 for all interactions), associations differed by alcohol intake level, with stronger associations among men (Q5 vs Q1 HR, 1.62; 95% CI, 1.05-2.49; P = .002 for trend) and women (Q5 vs Q1 HR, 1.33; 95% CI, 0.97-1.81; P = .03 for trend) not consuming alcohol; and by body weight, with stronger associations among overweight/obese men (Q5 vs Q1 HR, 1.48; 95% CI, 1.12-1.94; P = .008 for trend) and lean women (Q5 vs Q1 HR, 1.31; 95% CI, 0.99-1.74; P = .01 for trend). Conclusions and Relevance Findings suggest that inflammation is a potential mechanism linking dietary patterns and colorectal cancer development. Interventions to reduce the adverse role of proinflammatory diets may be more effective among overweight/obese men and lean women or men and women who do not consume alcohol.

Dietary Patterns and Colorectal Cancer Risk: a Review of 17 Years of Evidence (2000–2016)

Purpose of ReviewColorectal cancer (CRC) is a global public health problem, with an estimated 1.4 million cases diagnosed worldwide in 2012. Evidence suggests that diet may be important for primary prevention.Recent FindingsThe 2017 WCRF/AICR Continuous Update Project on colorectal cancer concluded that there is convincing evidence linking several individual dietary factors with CRC risk but the evidence for dietary patterns was limited and inconclusive. In addition, previous reviews and meta-analyses have not critically synthesized various dietary patterns. This review synthesized data from dietary patterns studies over a 17-year period from 2000 to 2016.SummaryWe included 49 studies (28 cohort and 21 case-control) that examined the association of index-based and empirically derived dietary patterns and CRC risk. A synthesis of food group components comprising the different index-based and empirically derived patterns revealed two distinct dietary patterns associated with CRC risk. A “healthy” pattern, generally characterized by high intake of fruits and vegetables, whole grains, nuts and legumes, fish and other seafood, milk, and other dairy products, was associated with lower CRC risk. In contrast, the “unhealthy” pattern, characterized by high intakes of red meat, processed meat, sugar-sweetened beverages, refined grains, desserts, and potatoes was associated with higher CRC risk. It is notable that the number of food groups, the intake quantity, and the exact types of foods in each food group differed between populations, yet the two dietary patterns remained consistent across regions, especially in empirically derived patterns, an indication of the high reproducibility of these patterns. However, findings for CRC risk in both index-based and empirically derived patterns, differed by sex, with stronger associations among men than women; study design, a higher proportion of case-control studies reported significant findings compared to prospective studies. Consuming a dietary pattern high in fruits and vegetables and low in meats and sweets is protective against CRC risk. However, important questions remain about the mechanisms underlying differences by sex; life-course timing of exposure to dietary patterns; interaction of dietary patterns with the microbiome or with lifestyle factors including physical activity; and elucidation of subsite differences.

Association between post-cancer diagnosis dietary inflammatory potential and mortality among invasive breast cancer survivors in the Women's Health Initiative

Background: Inflammation is important in chronic disease and can be modulated by dietary exposures. Our aim was to examine whether the inflammatory potential of diet after cancer diagnosis, assessed using the dietary inflammatory index (DII), is associated with all-cause and cause-specific mortality among women diagnosed with invasive breast cancer in the Womens Health Initiative (WHI). Methods: Our analytic cohort included 2,150 postmenopausal women, ages 50 to 79 years at baseline, who developed invasive breast cancer during follow-up and completed a food frequency questionnaire (FFQ) on average 1.5 years after diagnosis. Women were followed from breast cancer diagnosis until death or the end of follow-up by October 2014. Energy-adjusted DII (E-DII) scores were calculated from food plus supplements using a nutrient–density approach. Cox proportional hazards models were fit to estimate multivariable-adjusted HRs and 95% confidence intervals (CIs) for all-cause, breast cancer–specific, and cardiovascular disease (CVD) mortality. Results: After a median 13.3 years of follow-up, 580 deaths from any cause occurred, including 212 breast cancer deaths and 103 CVD deaths. Lower (i.e., more anti-inflammatory) E-DII scores were associated with a lower risk of CVD mortality (HRQ1VSQ4 = 0.44; 95% CI, 0.24–0.82; Ptrend = 0.005), but not with breast cancer–specific mortality (HRQ1VSQ4 = 0.96; 95% CI, 0.62–1.49; Ptrend = 0.96) or all-cause mortality (HRQ1VSQ4 = 0.82; 95% CI, 0.63–1.05; Ptrend = 0.17). Conclusions: Consuming a more anti-inflammatory diet after breast cancer diagnosis may be a means for reducing risk of death from CVD. Impact: Survival after invasive breast cancer diagnosis may be improved by consumption of an anti-inflammatory diet. Cancer Epidemiol Biomarkers Prev; 27(4); 454–63. ©2018 AACR.

Biomarker-calibrated nutrient intake and healthy diet index associations with mortality risks among older and frail women from the Women’s Health Initiative

Background: Although studies to date have confirmed the association between nutrition and frailty, the impact of dietary intake and dietary patterns on survivorship in those with frailty is yet to be examined in a well-powered cohort with validated frailty status. Moreover, previous studies were limited by measurement error from dietary self-reports.Objective: We derived biomarker-calibrated dietary energy and protein intakes to address dietary self-report error. Using these data, we then evaluated the association of mortality in older women with frailty and dietary intake and healthy diet indexes, such as the alternate Mediterranean Diet (aMED), the Dietary Approaches to Stop Hypertension (DASH) score, and the Dietary Inflammatory Index (DII).Design: The analytic sample included 10,034 women aged 65-84 y with frailty and complete dietary data from the Womens Health Initiative Observational Study. Frailty was assessed with modified Frieds criteria. Dietary data were collected by food-frequency questionnaire.Results: Over a mean follow-up period of 12.4 y, 3259 (31%) deaths occurred. The HRs showed progressively decreased rates of mortality in women with higher calibrated dietary energy intakes (P-trend = 0.003), higher calibrated dietary protein intakes (P-trend = 0.03), higher aMED scores (P-trend = 0.006), and higher DASH scores (P-trend = 0.02). Although the adjusted point estimates of HRs (95% CIs) for frail women scoring in the second, third, and fourth quartiles on DII measures were 1.15 (1.03, 1.27), 1.28 (1.15, 1.42), and 1.24 (1.12, 1.38), respectively, compared with women in the first quartile, no overall effect was observed across quartiles (P-trend = 0.35). Subgroup analyses by chronic morbidity or smoking status or by excluding women with early death did not substantially change these findings.Conclusions: The current study highlights the importance of nutrition in older, frail women. Diet quality and quantity should be considered in managing persons with frailty.

The association between an inflammatory diet and global cognitive function and incident dementia in older women: The Women's Health Initiative Memory Study

The Mediterranean and Dietary Approaches to Stop Hypertension diets have been associated with lower dementia risk. We evaluated dietary inflammatory potential in relation to mild cognitive impairment (MCI)/dementia risk.

The inflammatory potential of diet and ovarian cancer risk: results from two prospective cohort studies

Background:We used a food-based empirical dietary inflammatory pattern (EDIP) score to investigate whether diets with higher inflammatory potential are associated with increased ovarian cancer risk.Methods:We followed 186 314 women in the Nurses’ Health Study and Nurses’ Health Study-II, from 1984 to 2013, to examine associations between EDIP scores and ovarian cancer risk, using Cox regression analyses.Results:During 3 454 514 person-years of follow-up, 989 ovarian cancer cases were identified. In pooled multivariable-adjusted analyses, higher EDIP scores (more pro-inflammatory diets) were not significantly associated with ovarian cancer risk (HRquintile5vs1 0.99; 95% CI: 0.80–1.22; P-trend=0.97). Similarly, we found no evidence of heterogeneity by histologic subtype (P-heterogeneity=0.52) or by tumour aggressiveness (P-heterogeneity=0.63).Conclusions:In contrast with two previous case-control studies that found a positive association between a literature-derived nutrient-based dietary inflammatory index and ovarian cancer risk, our prospective analyses using a food-based score observed no evidence of an association.