Suzanne P. Murphy

Intake of Flavonoids and Lung Cancer

Background: To investigate the possible relationship between intake of flavonoids-powerful dietary antioxidants that may also inhibit P450 enzymes-and lung cancer risk, we conducted a population-based, case-control study in Hawaii. Methods: An in-person interview assessed smoking history and usual intake of 242 food items for 582 patients with incident lung cancer and 582 age-, sex-, and ethnicity-matched control subjects. Subjects who donated a blood sample were genotyped for the P450 enzyme variant allele CYP1A1 * 2 by use of a polymerase chain reaction-based method. Logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs). All P values are two-sided. Results: After adjusting for smoking and intakes of saturated fat and β-carotene, we found statistically significant inverse associations between lung cancer risk and the main food sources of the flavonoids quercetin (onions and apples) and naringin (white grapefruit). The lung cancer OR for the highest compared with the lowest quartile of intake was 0.5 (95% CI = 0.3-0.9) for onions (P for trend =.001) and 0.6 (95% CI = 0.4-1.0) for apples (P for trend =.03). The OR for the highest compared with the lowest tertile of intake for white grapefruit was 0.5 (95% CI = 0.2-0.9) (P for trend =.02). No association was found for important food sources of other flavonoids. Using published food-composition data for flavonoids, we found an inverse association between intake of quercetin and risk of lung cancer (P for trend =.07) that appears consistent with associations for its food sources. The effect of onions was particularly strong against squamous cell carcinoma (a cell type specifically associated with CYP1A1 * 2 in our study) and was modified by the CYP1A1 genotype, suggesting that CYP1A1 may play a role in this association. Conclusion: If replicated, particularly in prospective studies, these findings would suggest that foods rich in certain flavonoids may protect against certain forms of lung cancer and that decreased bioactivation of carcinogens by inhibition of CYP1A1 should be explored as underlying mechanisms.

Nutritional Importance of Animal Source Foods

Animal source foods can provide a variety of micronutrients that are difficult to obtain in adequate quantities from plant source foods alone. In the 1980s, the Nutrition Collaborative Research Support Program identified six micronutrients that were particularly low in the primarily vegetarian diets of schoolchildren in rural Egypt, Kenya and Mexico: vitamin A, vitamin B-12, riboflavin, calcium, iron and zinc. Negative health outcomes associated with inadequate intake of these nutrients include anemia, poor growth, rickets, impaired cognitive performance, blindness, neuromuscular deficits and eventually, death. Animal source foods are particularly rich sources of all six of these nutrients, and relatively small amounts of these foods, added to a vegetarian diet, can substantially increase nutrient adequacy. Snacks designed for Kenyan schoolchildren provided more nutrients when animal and plant foods were combined. A snack that provided only 20% of a childs energy requirement could provide 38% of the calcium, 83% of the vitamin B-12 and 82% of the riboflavin requirements if milk was included. A similar snack that included ground beef rather than milk provided 86% of the zinc and 106% of the vitamin B-12 requirements, as well as 26% of the iron requirement. Food guides usually recommend several daily servings from animal source food groups (dairy products and meat or meat alternatives). An index that estimates nutrient adequacy based on adherence to such food guide recommendations may provide a useful method of quickly evaluating dietary quality in both developing and developed countries.

Animal Source Foods Improve Dietary Quality, Micronutrient Status, Growth and Cognitive Function in Kenyan School Children: Background, Study Design and Baseline Findings

A previous longitudinal three-country study in Egypt, Kenya and Mexico found significant positive associations between intake of animal source foods (ASF) and growth, cognitive development and physical activity. To test for a causal relationship, a controlled school feeding intervention study was designed to test the hypotheses that ASF would improve micronutrient status, growth and cognitive function in Kenyan primary school children. Twelve rural Kenyan schools with 554 children were randomized to four feeding interventions using a local vegetable stew as the vehicle. The groups were designated as Meat, Milk, Energy and Control, who received no feedings. Feeding was carried out on school days for seven terms during 21 mo. Preintervention baseline measures included nutritional status, home food intake, anthropometry, biochemical measures of micronutrient status, malaria, intestinal parasites, health status and cognitive and behavioral measures. The measurements of each child were repeated at intervals over 2 y. Baseline data revealed stunting and underweight in approximately 30% of children and widespread inadequate intakes and/or biochemical evidence of micronutrient deficiencies, particularly of iron, zinc, vitamins A and B-12, riboflavin and calcium. Little or no ASF were eaten and fat intake was low. Malaria was present in 31% of children, and hookworm, amebiasis and giardia were widely prevalent. The outcomes measured were rates of change or increase during the intervention in cognitive function, growth, physical activity and behavior and micronutrient status. Hierarchical linear random effects modeling was used for analysis of outcomes.

Interpreting and using the Dietary References Intakes in dietary assessment of individuals and groups

For individuals, a statistical approach is available to compare observed intakes to the EAR or AI (to assess adequacy), and the UL (to assess risk of excess). A more qualitative assessment of intakes involves comparison directly to the RDA to evaluate adequacy, but this is accurate only if long-term usual intake is known. For groups of people, the prevalence of inadequacy can usually be estimated as the proportion with intakes below the EAR, while the prevalence of potentially excessive intakes is estimated as the proportion above the UL. The accuracy of all assessments depends on unbiased and accurate intake estimates as well as a consideration of the effects of day-to-day variation in intake. Nutrition practitioners will find the new DRIs useful for assessing diets in a variety of settings. Computerized assessment systems will be important tools when incorporating these theoretical concepts into dietetic practice.

Kenyan School Children Have Multiple Micronutrient Deficiencies, but Increased Plasma Vitamin B-12 Is the Only Detectable Micronutrient Response to Meat or Milk Supplementation

Animal source foods (ASF) can provide micronutrients in greater amounts and more bioavailable forms compared to plant source foods, but their intake is low in many poor populations. However, the impact of ASF on micronutrient status of undernourished populations has not been assessed. Supplemental meat (60-85 g/d), milk (200-250 mL/d) or energy (isocaloric with the meat and milk, 240-300 kcal/d) were randomly assigned to 555 undernourished school children aged 5-14 y in a rural malaria-endemic area of Kenya, at one school meal daily for one school year. Blood and stool samples were collected at baseline and after 1 y to assess stool parasites, malaria, hemoglobin, serum or plasma C-reactive protein, ferritin, iron, zinc, copper, vitamin B-12, folate and retinol, and erythrocyte riboflavin. At baseline, there was a high prevalence of micronutrient deficiencies (iron, zinc, vitamins A and B-12 and riboflavin), yet plasma ferritin was low in few children, and none had low serum copper. At the end of the year of supplementation, plasma vitamin B-12 concentrations were significantly increased in children fed the Meat or Milk meal; prevalence of severe plus moderate deficiency fell from 80.7% at baseline to 64.1% in the Meat group and from 71.6 to 45.1% in the Milk group, respectively. No significant improvement was observed in the status of other micronutrients compared to the Energy and Control groups, although malaria and other infections may have obscured effects. Supplementation with small amounts of meat or milk reduced the high prevalence of vitamin B-12 deficiency in these children.

Fat and meat intake and prostate cancer risk: The multiethnic cohort study

Dietary fat and meat as potential risk factors for prostate cancer have been the focus of many epidemiologic investigations, and findings from recent studies in particular have been inconsistent. Therefore, we examined the association between these exposures and prostate cancer risk in the Multiethnic Cohort Study. The analyses included 82,483 men in Hawaii and Los Angeles aged ≥45, who completed a detailed quantitative food frequency questionnaire in 1993–1996. During the follow‐up period of 8 years, a total of 4,404 incident cases, including 1,278 nonlocalized or high‐grade cancer cases, were identified. Cox proportional hazard models were used to estimate relative risks of prostate cancer after adjustment for time on study, ethnicity, family history of prostate cancer, education, body mass index, smoking status and energy intake. Intake of different types of fat (total, saturated, monounsaturated or polyunsaturated), n‐6 fatty acid, cholesterol, various meats, and fats from meat showed no association with overall prostate cancer risk or with nonlocalized or high‐grade prostate cancer. Furthermore, we found little evidence of any relation of fat and meat intake with prostate cancer risk within any of the 4 racial/ethnic groups (African Americans, Japanese Americans, Latinos and Whites). There was a suggestion of a protective effect of n‐3 fatty acid intake that was limited to Latinos and Whites. However, overall, our findings from a large cohort study of ethnically diverse population give no indication that intake of fat and meat substantially affects prostate cancer risk.

The Impact of Dietary Intervention on the Cognitive Development of Kenyan School Children

Previous observational studies in developing countries have suggested that diet quality, particularly increased animal source food (ASF) consumption, is positively associated with child cognitive development. This report presents findings from a study in rural Kenya, designed to test the impact of three different diets on the cognitive development of school children. Twelve schools with a total of 555 Standard 1 children (equivalent to U.S. Grade 1) were randomized to one of four feeding interventions: Meat, Milk, Energy or Control (no feeding). Feeding continued for seven school terms (21 mo), and cognitive tests were administered before the commencement of feeding and during every other term of feeding. Hierarchical linear random effects models and associated methods were used to examine the effects of treatment group on changes in cognitive performance over time. Analyses revealed that children receiving supplemental food with meat significantly outperformed all other children on the Ravens Progressive Matrices. Children supplemented with meat, and children supplemented with energy, outperformed children in the Control group on tests of arithmetic ability. There were no group differences on tests of verbal comprehension. Results suggest that supplementation with animal source food has positive effects on Kenyan childrens cognitive performance. However, these effects are not equivalent across all domains of cognitive functioning, nor did different forms of animal source foods produce the same beneficial effects. Implications of these findings for supplementation programs in developing countries are discussed.

Dietary Reference Intakes: summary of applications in dietary assessment

OBJECTIVE To summarise the applications and appropriate use of Dietary Reference Intakes (DRIs) as guidance for nutrition and health research professionals in the dietary assessment of groups and individuals. DESIGN Key points from the Institute of Medicine report, Dietary Reference Intakes: Applications in Dietary Assessment, are summarised in this paper. The different approaches for using DRIs to evaluate the intakes of groups vs. the intakes of individuals are highlighted. RESULTS Each of the new DRIs is defined and its role in the dietary assessment of groups and individuals is described. Two methods of group assessment and a new method for quantitative assessment of individuals are described. Illustrations are provided on appropriate use of the Estimated Average Requirement (EAR), the Adequate Intake (AI) and the Tolerable Upper Intake Level (UL) in dietary assessment. CONCLUSIONS Dietary assessment of groups or individuals must be based on estimates of usual (long-term) intake. The EAR is the appropriate DRI to use in assessing groups and individuals. The AI is of limited value in assessing nutrient adequacy, and cannot be used to assess the prevalence of inadequacy. The UL is the appropriate DRI to use in assessing the proportion of a group at risk of adverse health effects. It is inappropriate to use the Recommended Dietary Allowance (RDA) or a group mean intake to assess the nutrient adequacy of groups.

Food Supplements Have a Positive Impact on Weight Gain and the Addition of Animal Source Foods Increases Lean Body Mass of Kenyan Schoolchildren

Observational studies of dietary patterns and growth and studies with milk supplementation have shown that children consuming diets containing animal source foods grow better. This study evaluates the growth of 544 Kenyan schoolchildren (median age 7.1 y) after 23 mo of food supplementation with a meat, milk or energy supplement (approximately 1255 kJ) compared to a control group without a supplement. Multivariate analyses controlled for covariates compared gain in weight, height, weight-for-height Z-score (WHZ), height-for-age Z-score (HAZ), mid-upper-arm circumference, triceps and subscapular skinfolds, mid-upper-arm muscle and mid-upper-arm fat area. Children in each of the supplementation groups gained approximately 0.4 kg (10%) more weight than children in the Control group. Children in the Meat, Milk and Energy groups gained 0.33, 0.19 and 0.27 cm more, respectively, in mid-upper-arm circumference than children in the Control group. Children who received the Meat supplement gained 30-80% more mid-upper-arm muscle area than children in the other groups, and children who received the milk supplement gained 40% more mid-upper-arm muscle area than children who did not receive a supplement. No statistically significant overall effects of supplementation were found on height, HAZ, WHZ or measures of body fat. A positive effect of the milk supplement on height gain could be seen in the subgroup of children with a lower baseline HAZ (< or = -1.4). The results indicate that food supplements had a positive impact on weight gain in the study children and that the addition of meat increased their lean body mass.

Selecting Items for a Food Behavior Checklist for a Limited-Resource Audience

OBJECTIVE To report 6 psychometric properties of food behavior checklist (FBC) items and then to use these properties to systematically reduce the number of items on this evaluation tool. DESIGN Random assignment to the intervention and control groups. SETTING Low-income communities. PARTICIPANTS Women (N = 132) from limited-resource families. MAIN OUTCOME MEASURES Reliability, internal consistency, baseline differences by ethnicity, sensitivity to change, and criterion and convergent validity of subscales. RESULTS The fruit and vegetable subscale showed a significant correlation with serum carotenoid values (r =.44, P <.001), indicating acceptable criterion validity. Milk, fat/cholesterol, diet quality, food security, and fruit/vegetable subscales showed significant correlations with dietary variables. Nineteen items have acceptable reliability. Twenty items showed no baseline differences by ethnic group. Eleven of the 15 items expected to show change following the intervention demonstrated sensitivity to change. CONCLUSIONS AND IMPLICATIONS This brief food behavior checklist (16 items) is easy to administer to a client group, has an elementary reading level (fourth grade), and has a low respondent burden in addition to meeting requirements for validity, reliability, and sensitivity to change. This study establishes a process that can be used by other researchers to develop and further refine instruments for use in community health promotion interventions.