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April 2008 Highlights of This Issue
Traditional Diets and Breast Cancer in Hispanic and Non-Hispanic Women
Background Many modifiable factors such as dietary patterns, obesity, and physical inactivity are associated with the risk of breast
cancer. There are also genetic factors, including ethnicity, which can alter risk. For example, the breast cancer risk for Hispanic women is 30% lower than
the risk for non-Hispanic white women. As is the case for many relations between diet and health, it is likely that genetic or ethnic factors may modify
the association between dietary patterns and breast cancer risk. In the April 2008 issue of The American Journal of Clinical Nutrition, Murtaugh and
colleagues examine whether the association between dietary patterns and breast cancer risk is different in Hispanic and non-Hispanic women and whether
menopausal status and adiposity modify these effects.
Study Design These researchers used a case-control design to study women living in Arizona, New Mexico, Colorado, and Utah. Those
categorized as breast cancer cases (n = 2281) were identified from cancer registries, and women without breast cancer (controls, n = 2465)
were selected from mailing, driver’s license, and Medicare lists. Women were identified as Hispanic or non-Hispanic white and classified as pre- or
postmenopausal based on age and reproductive history. Dietary intake patterns were evaluated with the use of a dietary questionnaire. "Western" diets were
those emphasizing high-fat dairy foods, refined grains, fast foods, and red meats. "Native Mexican" patterns emphasized Mexican cheeses, soups, meat,
legumes, and tomato-based sauces. "Prudent" diets comprised low-fat dairy foods, whole grains, fruit, legumes, and vegetables. The "Mediterranean" diet
included more alcohol, poultry, seafood, and vegetables. Women consuming mostly reduced-calorie foods were classified as "Dieters."
Results Consumption of a Western diet increased risks of both pre- and postmenopausal breast cancer (87% and 47%, respectively;
P < 0.01) in non-Hispanic white women but not in their Hispanic counterparts. Consuming a Prudent diet increased cancer risk in non-Hispanic, white,
postmenopausal women (66%; P < 0.01) but not in other groups. Consuming a Native Mexican food pattern decreased risk in all women except the
postmenopausal Hispanic cohort, whereas the Mediterranean diet decreased risk only in postmenopausal Hispanic women. Dieting decreased breast cancer risk
only in pre-menopausal Hispanic subjects. Body mass index (BMI; in kg/m2) modified many of these associations. For example, the protective
effect of a Native Mexican diet was only evident in the thinnest women (BMI < 25).
Conclusions These data suggest that traditional Mexican and Mediterranean diets are related to lower breast cancer risk, but these
effects are influenced by ethnicity, adiposity, and menopausal status. A similar result was found for consumption of a Prudent diet. Future studies should
consider these important interactions when investigating the relation between diet and cancer risk. Clearly, one dietary pattern may not fit all.
Reference Murtaugh MA,
Sweeney C, Giuliano AR, et al. Diet patterns and breast cancer risk in Hispanic and non-Hispanic white women: the Four-Corners Breast Cancer Study.
American Journal of Clinical Nutrition 2008;87: 978–84.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/reprint/87/4/978
To contact the corresponding author, Maureen A Murtaugh, please send an e-mail to
maureen.murtaugh{at}hsc.utah.edu.
Egg Consumption, Diabetes, and Mortality—A Complex Relation
Background The Dietary Guidelines for Americans recommends that we consume <300 mg cholesterol/d, and many health professionals
recommend limiting consumption of eggs because of their cholesterol content. Eggs, however, are a good source of many essential nutrients, and although
circulating cholesterol is related to the risk of cardiovascular disease, the relation between dietary cholesterol and blood cholesterol is complex.
Research suggests that dietary cholesterol does not influence blood cholesterol in many individuals, but may in others, such as those with diabetes.
Although the relation between egg consumption and the risk of cardiovascular events has been studied, the data are limited and inconsistent. In response,
Djoussé and Gaziano assessed the risk of consuming eggs on cardiovascular disease and overall mortality, and their results are published in the
April 2008 issue of The American Journal of Clinical Nutrition. In an accompanying editorial, Eckel discusses these data in light of other studies,
possible mechanisms, and overall health recommendations.
Study Design Using data from the Physicians' Health Study, egg consumption was ascertained from 21,327 male physicians (mean age:
53.7 y) with the use of a semiquantitative food-frequency questionnaire. In addition to general information concerning overall diet, participants reported
how often they consumed eggs during the past year, and their responses were used to estimate weekly egg consumption: <1, 1, 2–4, 5–6, or
7 eggs/wk. Information on egg consumption was updated every 2 y for the first 10 y of the study, and
information concerning cardiovascular events and deaths was collected longitudinally for 20 y.
Results Egg consumption was relatively low in the study participants, with 52% consuming
1 egg/wk and only 8% consuming 1 egg/d. Higher egg consumption
was associated with increasing age, adiposity, smoking, alcohol consumption, physical inactivity, diabetes, hypertension, and use of multivitamins. When
all data were considered together and adjusted for potential confounding factors, egg consumption was not related to the risk of myocardial infarction
(heart attack) or stroke. However, men consuming the most eggs had a 23% increased risk of all-cause death during the 20-y study period. This relation was
strongest in subjects with diabetes, in whom consumption of 5–6 or 7 eggs/wk was related to 2.27- and
2.01-fold increased risk of death, respectively.
Conclusions These data suggest that consuming 1 egg/d moderately increases the risk of death, but not
via cardiovascular events, and that this relation is stronger in men with prevalent diabetes. Eckel, in his accompanying editorial, reminds us that "...eggs
are like all other foods—they are neither "good" nor "bad," and they can be part of an overall heart-healthy diet." However, if you are a male
physician with diabetes, you may want to do without the yolks.
Reference Djoussé L,
Gaziano JM. Egg consumption in relation to cardiovascular disease and mortality: the Physicians' Health Study. American Journal of Clinical Nutrition
2008;87: 964–9.
Eckel RH. Egg consumption in relation to cardiovascular disease and mortality: the story gets more complex. American Journal of Clinical Nutrition
2008;87: 799–800.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/reprint/87/4/964
To contact the corresponding author, Luc Djoussé, please send an e-mail to
ldjousse{at}rics.bwh.harvard.edu or contact the Office of Public Relations, Brigham and Women's Hospital
at 617-534-1603.
For the complete editorial, please go to the following URL:
http://www.ajcn.org/cgi/reprint/87/4/799
To contact the corresponding author, Robert Eckel, please send an e-mail to robert.eckel{at}uchsc.edu.
Is Your Child a Picky Eater? Genetics May Play a Role
Background Many factors influence what a child eats, and in this era of burgeoning childhood obesity, understanding them is
increasingly important. Research indicates an interplay between environmental and genetic influences in determining dietary consumption patterns. However,
these studies have been conducted on adults or animal models. Because food intake patterns may already be established during childhood, Faith and
colleagues, in a study published in the April 2008 issue of The American Journal of Clinical Nutrition, tested the magnitude of genetic and
environmental influences on food and beverage intake in 7-y-old boys and girls. They also investigated whether adiposity is related to intake of specific
foods and beverages.
Study Design These investigators used a classic twin design to test their hypotheses. Twin pairs (n = 396; mean age: 7.4 y)
were recruited from the MacArthur Longitudinal Study of Twins. Of the pairs, 214 were identical (monozygotic) and 182 were fraternal (dizygotic); each twin
pair had been raised together. The use of both groups of twins was crucial because identical twins are assumed to be genetically identical, whereas
fraternal twins are assumed to be ~50% genetically similar. Moreover, regardless of whether they are identical or fraternal, each twin in a pair has
experienced a set of shared environmental influences (eg, typical meal patterns in the household) as well as a set of unique or nonshared environmental
influences (eg, what they do individually with their parents). Body mass index (BMI; in kg/m2) was measured by study personnel or the twins'
parents, and food and beverage intakes were estimated via 24-h dietary recalls completed by the parents. Recalled foods and beverages were classified into
9 composite categories (eg, peanut butter and jelly, bread and butter, fish with lemon). The researchers statistically estimated the proportion of
variability in food and beverage intake patterns attributed to genetic and environmental factors. They also tested whether BMI is related to intake of
specific food-beverage categories.
Results Foods and beverages chosen by monozygotic twins were more similar than those consumed by dizygotic twins. However, genetics
seemed to influence the boys' and girls' intakes differently, significantly affecting 7 and 3 of the food categories, respectively. For example, 79% of the
variability in peanut butter and jelly intake could be explained by genetics in the boys, whereas there was no apparent genetic component for this food
composite in girls. Of the variability in fish and lemon intake, 12% and 56% were genetically-influenced in the boys and girls, respectively. Results
suggest that shared environmental factors were more influential for girls than for boys. BMI generally was not related to intake of specific food-beverage
categories.
Conclusions This study documents sizable genetic influences on food and beverage intake in 7-y-old children and suggests that these
effects differ by sex. In general, shared environmental factors were more important than genetics in determining food and beverage choices in girls than in
boys. Future studies will need to use more rigorous food intake methodologies to determine if these relations result in alterations in total energy and
nutrient intakes leading to obesity.
Reference Faith MS, Rhea SA,
Corley RP, Hewitt JK. Genetic and shared environmental influences on children's 24-h food and beverage intake: sex differences at age 7 y. American
Journal of Clinical Nutrition 2008;87:903–11.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/reprint/87/4/903
To contact the corresponding author, Myles S Faith, please send an e-mail to mfaith{at}mail.med.upenn.edu.
Diet High in Monounsaturated Fats May Help Regulate Blood Glucose
Background Despite years of intense interest, the amount and composition of fats and carbohydrates that should be in the diet to
promote optimal health is still hotly debated. Currently, the Dietary Guidelines for Americans recommends that we keep total fat intake between 20%
and 35% of calories, with most coming from poly- and monounsaturated fatty acids (MUFAs). They also suggest that we obtain 45–65% of our calories from
carbohydrates. However, some studies suggest that a higher-fat, lower-carbohydrate diet containing even more MUFAs may be beneficial, especially in
individuals with type 2 diabetes. In a study published in the April 2008 issue of The American Journal of Clinical Nutrition, a group of Danish
researchers compared the effects of a relatively high-fat, high-MUFA diet on indicators of glucose homeostasis in men and women who were trying to maintain
weight loss after successful weight reduction.
Study Designs These investigators conducted a 6-mo, randomized, dietary intervention study in 46 subjects (mean age: ~28 y) who had
previously lost 8% of their body weight by consuming a low-calorie diet for 8 wk. The subjects were assigned
to 1 of 3 intervention groups: high-MUFA (MUFA; n = 16), low-fat (LF; n = 18), or low-MUFA (control; n = 12). MUFA, LF, and control
diets provided 40%, 25%, and 35% of calories from fat; >20%, 10%, and 10% of calories from MUFAs; and 45%, 60%, and 50% of calories from carbohydrates,
respectively. The subjects were provided with appropriate food choices at no cost via a supermarket established by the investigators, received dietary
counseling while shopping, and were not allowed to check out until their food choices were appropriate. Weight, height, and body composition were measured
at the beginning and completion of the dietary intervention, and a 2-h oral-glucose-tolerance test (OGTT) was performed to ascertain measures of glucose
homeostasis.
Results The dietary intervention group to which a subject belonged had no effect on energy intake, body weight, or body mass index at
the completion of the study. However, compared with controls whose values increased during the study, fasting glucose and insulin concentrations of those
consuming the MUFA diet decreased (P < 0.05). Similar results were found for a composite variable reflecting insulin resistance (homeostasis model
assessment of insulin resistance), such that consumption of the MUFA diet conferred beneficial effects compared with consumption of the control diet.
Parallel trends were found between the effects of the MUFA and LF diets (compared with the control diet), although the effects were not significant. There
were no differences in glucose or insulin response to the OGTT between dietary intervention groups.
Conclusions These data suggest a potential benefit of consuming a relatively high-fat, high-MUFA diet (compared with a typical Western
diet or perhaps even an LF diet) on glucose homeostasis during weight maintenance subsequent to weight loss. Additional studies with older subjects,
including those with type 2 diabetes, will be important to determine whether these potentially favorable effects might be even more pronounced in a more
at-risk population.
Reference Due A, Larsen TM,
Hermansen K, et al. Comparison of the effects on insulin resistance and glucose tolerance of 6-mo high-monounsaturated-fat, low-fat, and control diets.
American Journal of Clinical Nutrition 2008;87:855–62.
For More Information For the complete article, please go to the following URL:
http://www.ajcn.org/cgi/reprint/87/4/855
To contact the corresponding author, Arne Astrup, please send and e-mail to
ast{at}life.ku.dk.
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