Walter C Willett

Harvard University | Harvard · Department of Nutrition

Background Valid and efficient tools for measuring and tracking diet quality globally are lacking. Objective The objective of the study was to develop and evaluate a new tool for rapid and cost-efficient diet quality assessment. Design Two screener versions were designed using Prime Diet Quality Score (PDQS), one in a 24-hour recall (PDQS-24HR) a...

Background Standard diet quality assessment tools, which measure micronutrient sufficiency and food consumption related to disease and applicable to different populations, are needed to track progress in meeting the Sustainable Development Goals related to hunger, food security, and nutrition. Diet quality scores have been constructed for high- and...

Background: Dietary diversity scores (DDS) are considered as metrics for monitoring the implementation of the UN’s Sustainable Development Goals, but they need to be rigorously evaluated. Objective: To examine two DDS, the Food Groups Index (FGI), and the Minimum Dietary Diversity-Women (MDD-W), alongside two dietary quality scores, the Alternate...

Epidemiologic evidence on the association of antioxidant intake and prostate cancer incidence is inconsistent. Total antioxidant intake and prostate cancer incidence has not previously been examined. Using the ferric reducing antioxidant potential (FRAP) assay, the total antioxidant content (TAC) of diet and supplements were assessed in relation to...

Previous evidence suggests that variants in the fat mass and obesity-associated gene (FTO) affect adiposity in an age-dependent fashion in children, and nutritional factors may modify genotype effects. We assessed the effect of FTO rs9939609 on BMI and BMI-for-age Z score changes during childhood in a population-based longitudinal study in the Braz...

Most studies on the prevalence of supplement use in the United States were cross-sectional or evaluated trends in limited variety of supplements. The objective of this study was to describe the longitudinal and secular trend of dietary supplement use over the past 20 years in health professionals using data from two large prospective cohorts. We an...

Heterocyclic amines (HCAs) are mutagenic compounds generated when meats are cooked at high temperature and for long duration. The findings from previous studies on the relation between HCAs and breast cancer are inconsistent, possibly because of genetic variations in the enzymes metabolizing HCAs. To evaluate whether the associations of intakes of...

Dietary guidelines recommend increasing fruit and vegetable intake and, most recently, have also suggested increasing variety. We prospectively examined the independent roles of quantity and variety in fruit and vegetable intake in relation to incident coronary heart disease (CHD). We prospectively followed 71,141 women from the Nurses' Health Stud...

Inflammation is considered as a mechanism leading to depression, but the association between inflammatory dietary pattern and depression risk is unknown. Using reduced-rank regression, we identified a dietary pattern that was related to plasma levels of inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor receptor 2), and...

Insulin may promote breast cancer directly by stimulating the insulin receptor or indirectly by increasing the plasma concentration of active sex hormones. The association between insulin and breast density, a strong breast cancer risk factor, has not been thoroughly studied. We measured associations between c-peptide (a molar marker of insulin sec...

Colonoscopy and sigmoidoscopy provide protection against colorectal cancer, but the magnitude and duration of protection, particularly against cancer of the proximal colon, remain uncertain. We examined the association of the use of lower endoscopy (updated biennially from 1988 through 2008) with colorectal-cancer incidence (through June 2010) and...

Previous investigations, of adolescent diet recalled in adulthood, found lower risk for benign breast disease (BBD) with higher intakes of vegetable fat and nuts during high school. We investigate whether vegetable protein and fat, derived from diets reported during pre-adolescence and adolescence, are associated with subsequent risk for BBD in you...

Importance: Information about diet after myocardial infarction (MI) and mortality is limited, despite the growing number of MI survivors in the United States. Objective: To examine the association of post-MI dietary quality and changes from pre- to post-MI with all-cause and cardiovascular mortality among MI survivors. Design, setting, and part...

To determine whether individual fruits are differentially associated with risk of type 2 diabetes. Prospective longitudinal cohort study. Health professionals in the United States. 66 105 women from the Nurses' Health Study (1984-2008), 85 104 women from the Nurses' Health Study II (1991-2009), and 36 173 men from the Health Professionals Follow-up...

Adult alcohol consumption during the previous year is related to breast cancer risk. Breast tissue is particularly susceptible to carcinogens between menarche and first full-term pregnancy. No study has characterized the contribution of alcohol consumption during this interval to risks of proliferative benign breast disease (BBD) and breast cancer....

The relation between sugar-sweetened beverages (SSBs) and body weight remains controversial. We conducted a systematic review and meta-analysis to summarize the evidence in children and adults. We searched PubMed, EMBASE, and Cochrane databases through March 2013 for prospective cohort studies and randomized controlled trials (RCTs) that evaluated...

We thank Schimek for his thoughtful letter. We agree that the American Association of State Highway and Transportation Officials (AASHTO) encourages bike paths; however, AASHTO's definition of a bike path is a shared use path for pedestrians, skaters, wheelchair users, joggers, and other nonmotorized users. AASHTO discourages bicycle-only cycle tra...

Later menopause is a risk factor for breast and endometrial cancer, yet few studies have investigated dietary predictors of this potentially modifiable event. In particular, dairy contains hormones and growth factors that could potentially impact menopausal timing. We therefore assessed the association between regular consumption of dairy foods and...

& Aims: Increased intake of dietary fiber has been proposed to reduce risk of inflammatory bowel diseases (Crohn's disease [CD], ulcerative colitis [UC]). However, few prospective studies have examined associations between long-term intake of dietary fiber and risk of incident CD or UC. We collected and analyzed data from 170,776 women, followed ov...

Dietary fats influence intestinal inflammation and regulate mucosal immunity. Data on the association between dietary fat and risk of Crohn's disease (CD) and ulcerative colitis (UC) are limited and conflicting. We conducted a prospective study of women enrolled in the Nurses' Health Study cohorts. Diet was prospectively ascertained every 4 years u...

Objective: To evaluate the association between coffee and caffeine consumption and suicide risk in three large-scale cohorts of US men and women. Methods: We accessed data of 43,599 men enrolled in the Health Professionals Follow-up Study (HPFS, 1988-2008), 73,820 women in the Nurses' Health Study (NHS, 1992-2008), and 91,005 women in the NHS II...

In light of research linking sugar-sweetened beverage consumption to obesity, the US Department of Agriculture, the American Academy of Pediatrics, and other organizations have formulated recommendations on healthy beverages. These guidelines consistently recommend limiting consumption of all calorie-containing liquids, except reduced-fat milk, of...

Without data from randomized trials, the long-term effects of fish consumption on coronary heart disease (CHD) need to be inferred from observational studies. We estimated CHD risk under different hypothetical interventions on fish consumption during mid- and later life in 2 prospective US cohorts of 25,797 men in the Health Professionals Follow-Up...

The isotemporal substitution model (ISM) was previously developed as a methodology to study the time-substitution effects of 1 type of activity for another in a data setting with continuous outcomes. To demonstrate the application of ISM with a dichotomous outcome, we prospectively examined the associations of different activities with various acti...

Adolescent diet may be etiologically relevant for colorectal carcinogenesis. We examined the association between meat and fish intakes during adolescence and the risk of colorectal adenomas later in life among 19,771 women participating in the Nurses' Health Study II. Subjects had completed a validated food frequency questionnaire in 1998 (when age...

Importance: Red meat consumption has been consistently associated with an increased risk of type 2 diabetes mellitus (T2DM). However, whether changes in red meat intake are related to subsequent T2DM risk remains unknown. Objective: To evaluate the association between changes in red meat consumption during a 4-year period and subsequent 4-year r...

Lignans are plant-based phytoestrogens with both estrogenic and anti-estrogenic properties that may be important for breast carcinogenesis. Retrospective studies have observed decreased breast cancer risk associated with high circulating enterolactone concentrations, a biomarker of lignan intake, but results from prospective studies are conflicting...

Background: Little is known about the association between eating patterns and type 2 diabetes (T2D) risk in women. Objective: The objective was to examine prospectively associations between regular breakfast consumption, eating frequency, and T2D risk in women. Design: Eating pattern was assessed in 2002 in a cohort of 46,289 US women in the N...

Importance: Nearly 2.5 million men currently live with prostate cancer in the United States, yet little is known about the association between diet after diagnosis and prostate cancer progression and overall mortality. Objective: To examine postdiagnostic fat intake in relation to lethal prostate cancer and all-cause mortality. Design, setting,...

Objective: Emerging evidence suggests that prenatal exposures may affect long-term health outcomes. In utero exposure to smoking is associated with an increased risk of overweight and obesity in children and adolescents. However, few studies have examined how prenatal exposure to parental smoking influences the risk of obesity during adulthood and...

Objective: Adjustment for body weight and physical activity has been suggested as an alternative to adjusting for reported energy intake in nutritional epidemiology. We examined which of these approaches would yield stronger correlations between nutrients and their biomarkers. Design: A cross-sectional study in which dietary fatty acids, caroten...

Objectives: We studied state-adopted bicycle guidelines to determine whether cycle tracks (physically separated, bicycle-exclusive paths adjacent to sidewalks) were recommended, whether they were built, and their crash rate. Methods: We analyzed and compared US bicycle facility guidelines published between 1972 and 1999. We identified 19 cycle t...

Background: Adherence to a Mediterranean diet may help prevent cognitive decline in older age, but studies are limited. We examined the association of adherence to the Mediterranean diet with cognitive function and decline. Methods: We included 6174 participants, aged 65+ years, from the cognitive substudy of the Women's Health Study. Women prov...

Relationships between some risk factors and breast cancer incidence are known to vary by tumor subtype. However, breast tumors can be classified according to a number of markers, which may be correlated, making it difficult to identify heterogeneity of risk factors with specific tumor markers when using standard competing-risk survival analysis. In...

We assessed the relationship between sleep duration, snoring and colorectal cancer risk. Prospective cohort studies. United States. A total of 30,121 men aged 41 to 79 years in the Health Professionals Follow-up Study and 76,368 women aged 40 to 73 years in the Nurses' Health Study. None. We queried information on sleep duration and snoring in 1986...

PURPOSEAlcohol intake is associated with increased risk of breast cancer. In contrast, the relation between alcohol consumption and breast cancer survival is less clear.Patients And methodsWe assessed pre- and postdiagnostic alcohol intake in a cohort of 22,890 women with incident invasive breast cancer who were residents of Wisconsin, Massachusett...

Background: Seafood consumption may prevent age-related cognitive decline. However, benefits may vary by nutrient contents in different seafood types. We examined associations between total seafood consumption and cognitive decline and whether these associations differ by seafood types. Methods: We conducted a prospective cohort study of 5,988 w...

Previous investigations found high dairy intakes in girls associated with rapid height growth and excess weight gain, which had opposite relationships with benign breast disease (BBD) in young women. We use data from the longitudinal Growing Up Today Study (GUTS) to investigate whether dairy intakes, in older children/adolescents, are associated wi...

In previous studies of postmenopausal women, overall intake of fruits and vegetables groups has been inversely associated with estrogen receptor-negative (ER-) breast cancer. In this analysis, we prospectively examined the associations of specific fruits and vegetables with risk of ER- postmenopausal breast cancer among 75,929 women aged 38-63 year...

Background: Dietary and circulating carotenoids have been inversely associated with breast cancer risk, but observed associations may be due to confounding. Single-nucleotide polymorphisms (SNPs) in β-carotene 15,15'-monooxygenase 1 (BCMO1), a gene encoding the enzyme involved in the first step of synthesizing vitamin A from dietary carotenoids, h...

Introduction Prior research supports an association between endogenous sex steroids and breast cancer among postmenopausal women; the association is less clear among premenopausal women. Methods We evaluated the associations between estrogens, androgens, progesterone and sex hormone binding globulin (SHBG) and breast cancer in a nested case-contro...

Purpose: The associations between bowel movement frequency, laxative use, and colorectal cancer incidence remain uncertain. No published studies have accounted for potential latency between these factors and colorectal cancer onset. Methods: We prospectively examined these associations among 88,173 women in the Nurses' Health Study (NHS, 1982-20...

To determine if obesity and dietary quality in low-income children differed by participation in the Supplemental Nutrition Assistance Program (SNAP), formerly the Food Stamp Program. The study population included 5193 children aged 4 to 19 with household incomes ≤130% of the federal poverty level from the 1999-2008 NHANES. Diet was measured by usin...

Magnesium is associated with lower risk of sudden cardiac death, possibly through antiarrhythmic mechanisms. Magnesium influences endothelial function, inflammation, blood pressure, and diabetes, but a direct relation with coronary heart disease (CHD) risk has not been established. We prospectively examined the association between dietary and plasm...

Walnuts are rich in polyunsaturated fatty acids and have been shown to improve various cardiometabolic risk factors. We aimed to investigate the association between walnut intake and incident type 2 diabetes in 2 large cohort studies: the Nurses' Health Study (NHS) and NHS II. We prospectively followed 58,063 women aged 52-77 y in NHS (1998-2008) a...

Background: Acrylamide is a probable human carcinogen formed during cooking of starchy foods. Two large prospective cohort studies of dietary acrylamide intake and ovarian cancer risk observed a positive association, although two other studies reported no association. Methods: We measured acrylamide exposure using red blood cell acrylamide and g...

The etiology of endometriosis is poorly understood, and few modifiable risk factors have been identified. Dairy foods and some nutrients can modulate inflammatory and immune factors, which are altered in women with endometriosis. We investigated whether intake of dairy foods, nutrients concentrated in dairy foods, and predicted plasma 25-hydroxyvit...

Purpose: Carotenoids have been hypothesized to prevent carcinogenesis through their antioxidant and pro-vitamin A properties. We examined associations between intakes of specific carotenoids and risk of colorectal adenomas. Methods: Among 29,363 men who reported having a lower bowel endoscopy between 1986 and 2006, 3,997 cases of colorectal aden...

In replySeigel and Richoz write that our study1 combining observational data from 3 trials2- 5 reflects a “fragment of data.” As noted,1 only 17 of 374 patients randomized to the vitamin A groups were excluded owing to outlying Early Treatment Diabetic Retinopathy Study visual acuity values or because they participated in more than 1 trial. Therefo...

The Supplemental Nutrition Assistance Program (SNAP), the largest federal food assistance program, currently serves 44.7 million Americans with a budget of $75 billion in 2011. This study engaged leading experts for in-depth, semi-structured interviews to explore their opinions concerning the existing challenges and barriers to eating nutritiously...

Background Estrogen receptor-negative (ER(-)) breast cancer has few known or modifiable risk factors. Because ER(-) tumors account for only 15% to 20% of breast cancers, large pooled analyses are necessary to evaluate precisely the suspected inverse association between fruit and vegetable intake and risk of ER(-) breast cancer.Methods Among 993 466...

It has been hypothesized that a high intake of dairy protein may increase prostate cancer risk by increasing the production of insulin-like growth factor 1 (IGF-1). Several single nucleotide polymorphisms (SNPs) have been weakly associated with circulating concentrations of IGF-1 and IGF binding protein 3 (IGFBP-3), but none of these SNPs was assoc...

Objective: To examine the long-term relationship between changes in water and beverage intake and weight change. Subjects: Prospective cohort studies of 50013 women aged 40-64 years in the Nurses' Health Study (NHS, 1986-2006), 52987 women aged 27-44 years in the NHS II (1991-2007) and 21988 men aged 40-64 years in the Health Professionals Follo...

Accumulating evidence points towards a role for sugar and other refined carbohydrates in the development of overweight Sugar—most importantly sucrose (table sugar) and high fructose corn syrup—has long been thought to have adverse health effects, such as contributing to dental caries, overweight, diabetes, and heart disease. A linked feature (doi...

Fetal exposure to parental smoking may lead to developmental adaptations and promote various diseases in later life. This study evaluated the associations of parental smoking during pregnancy with the risk of hypertension in the daughter in adulthood, and assessed whether these associations are explained by birth weight or body weight throughout li...

Objective: To determine public attitudes towards federal spending on nutrition assistance programmes and support for policies to improve the nutritional impact of the Supplemental Nutrition Assistance Program (SNAP). Design: Participants answered survey questions by telephone assessing support for SNAP spending and proposed programme policy chan...

Observational studies have found an inverse association between type 2 diabetes (T2D) and prostate cancer (PCa), and genome-wide association studies have found common variants near 3 loci associated with both diseases. The authors examined whether a genetic background that favors T2D is associated with risk of advanced PCa. Data from the National C...

The worldwide increase in obesity and related chronic diseases has largely been driven by global trade liberalization, economic growth and rapid urbanization. These factors continue to fuel dramatic changes in living environments, diets and lifestyles in ways that promote positive energy balance. Nutritional transitions in low-income and middle-inc...

Background: Consumption of caffeinated beverages such as coffee and tea has been associated with a lower risk of type 2 diabetes (T2D). Paradoxically, short-term metabolic studies have shown that caffeine impairs postprandial glycemic control. Objective: The objective was to prospectively examine the association of caffeinated compared with caff...

Background: Carotenoids have been hypothesized to reduce the risk of many diseases, but associations with intakes or blood concentrations may arise from other constituents of fruit and vegetables. Use of genetic variation in β-carotene 15,15'-monooxygenase 1 (BCMO1), a key enzyme in provitamin A carotenoid metabolism, as a surrogate for carotenoid...

Apart from the specific findings of this analysis, the authors encourage the use of what they call a nutrient-wide association study (NWAS), analogous to a genome-wide association study (GWAS), to investigate dietary determinants of health outcomes(1). Similar to the agnostic approach used in a GWAS, the features of their approach include: the incl...

The Supplemental Nutrition Assistance Program (SNAP) aims to alleviate hunger among its beneficiaries by providing benefits to purchase nutritious foods. We conducted a comprehensive dietary analysis of low-income adults and examined differences in dietary intake between SNAP participants and nonparticipants. The study population comprised 3835 non...

Meat, milk, and eggs have been inconsistently associated with the risk of advanced prostate cancer. These foods are sources of choline-a nutrient that may affect prostate cancer progression through cell membrane function and one-carbon metabolism. No study has examined dietary choline and the risk of lethal prostate cancer. Our objective was to exa...

Previous studies on gene-lifestyle interaction and obesity have focused mostly on the FTO gene and physical activity, whereas little attention has been paid to sedentary behavior as indicated by television (TV) watching. We analyzed interactions between TV watching, leisure time physical activity, and genetic predisposition in relation to body mass...

Purpose: The associations between use of aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen and breast cancer incidence in postmenopausal women are uncertain. We examined these associations with breast cancer, both overall and by molecular subtype. Patients and methods: We observed 84,602 postmenopausal women, free o...

Purpose: We examined the association between caffeine and caffeinated beverage consumption in relation to the risk of exfoliation glaucoma or exfoliation glaucoma suspect (EG/EGS). Methods: We followed 78,977 women from the Nurses' Health Study (NHS) and 41,202 men from the Health Professionals Follow-up Study (HPFS) who were at least 40 years o...

The relation between vitamin B-6 intake and colorectal cancer risk remains uncertain. We prospectively evaluated whether a higher vitamin B-6 intake in the remote past is more strongly associated with a lower risk of colorectal cancer than is an intake in the recent past in the Nurses' Health Study and the Health Professionals Follow-Up Study. We a...

Fruit and vegetable intake may protect against pancreatic cancer, since fruits and vegetables are rich in potentially cancer-preventive nutrients. Most case-control studies have found inverse associations between fruit and vegetable intake and pancreatic cancer risk, although bias due to reporting error cannot be ruled out. In most prospective stud...

Background The role of weight training in the primary prevention of type 2 diabetes mellitus (T2DM) is largely unknown. Methods To examine the association of weight training with risk of T2DM in US men and to assess the influence of combining weight training and aerobic exercise, we performed a prospective cohort study of 32 002 men from the Health...

Dietary n-3 PUFAs are inversely associated with risk of sudden cardiac death (SCD); however, little is known about other fats and SCD. Furthermore, concerns have been raised that high n-6 PUFA intake may attenuate the benefits of n-3 PUFAs. We examined associations and selected interactions between dietary fatty acids, expressed as a proportion of...

The results of meta-analyses examining the relationship between vitamin D supplementation and fracture reduction have been inconsistent. We pooled participant-level data from 11 double-blind, randomized, controlled trials of oral vitamin D supplementation (daily, weekly, or every 4 months), with or without calcium, as compared with placebo or calci...

By modulating immune function, vitamin D might increase innate immunity and inhibit the growth of initial bacterial invasion and protect against tuberculosis infection. We examined the effect of vitamin D supplementation on tuberculin skin test (TST) conversion. A double-blind, placebo-controlled study w