MEDLINE
Abstracts
What's new in research on diet in the role of disease
prevention? Find out in this easy-to-navigate collection of recent MEDLINE
abstracts compiled by the editors at Medscape.
Stampfer MJ, Hu FB, Manson JE, Rimm EB, Willett WC
N Engl J Med. 2000;343(1):16-22
Background:
Many lifestyle-related risk factors for coronary heart disease have been
identified, but little is known about their effect on the risk of disease when
they are considered together.
Methods: We followed 84,129 women participating in the Nurses'
Health Study who were free of diagnosed cardiovascular disease, cancer, and
diabetes at base line in 1980. Information on diet and lifestyle was updated
periodically. During 14 years of follow-up, we documented 1128 major coronary
events (296 deaths from coronary heart disease and 832 nonfatal infarctions).
We defined subjects at low risk as those who were not currently smoking, had a body-mass
index (the weight in kilograms divided by the square of the height in meters)
under 25, consumed an average of at least half a drink of an alcoholic beverage
per day, engaged in moderate-to-vigorous physical activity (which could include
brisk walking) for at least half an hour per day, on average, and scored in the
highest 40 percent of the cohort for consumption of a diet high in cereal
fiber, marine n-3 fatty acids, and folate, with a high ratio of polyunsaturated
to saturated fat, and low in trans fat and glycemic load, which reflects the
extent to which diet raises blood glucose levels.
Results: Many of the factors were correlated, but each
independently and significantly predicted risk, even after further adjustment
for age, family history, presence or absence of diagnosed hypertension or
diagnosed high cholesterol level, and menopausal status. Women in the low-risk
category (who made up 3 percent of the population) had a relative risk of
coronary events of 0.17 (95 percent confidence interval, 0.07 to 0.41) as
compared with all the other women. Eighty-two percent of coronary events in the
study cohort (95 percent confidence interval, 58 to 93 percent) could be
attributed to lack of adherence to this low-risk pattern.
Conclusion: Among women, adherence to lifestyle guidelines
involving diet, exercise, and abstinence from smoking is associated with a very
low risk of coronary heart disease.
Liu S,
Manson JE, Lee IM, et al
Am J Clin Nutr. 2000;72(4):922-928
Background:
Prospective data relating fruit and vegetable intake to cardiovascular disease
(CVD) risk are sparse, particularly for women.
Objective: In a large, prospective cohort of women, we
examined the hypothesis that higher fruit and vegetable intake reduces CVD
risk.
Design: In 1993 we assessed fruit and vegetable intake among
39876 female health professionals with no previous history of CVD or cancer by
use of a detailed food-frequency questionnaire. We subsequently followed these
women for an average of 5 y for incidence of nonfatal myocardial infarction
(MI), stroke, percutaneous transluminal coronary angioplasty, coronary artery
bypass graft, or death due to CVD.
Results: During 195647 person-years of follow-up, we
documented 418 incident cases of CVD including 126 MIs. After adjustment for
age, randomized treatment status, and smoking, we observed a significant
inverse association between fruit and vegetable intake and CVD risk. For
increasing quintiles of total fruit and vegetable intake (median servings/d: 2.
6, 4.1, 5.5, 7.1, and 10.2), the corresponding relative risks (RRs) were 1.0
(reference), 0.78, 0.72, 0.68, and 0.68 (95% CI comparing the 2 extreme
quintiles: 0.51, 0.92; P: for trend = 0.01). An inverse, though not
statistically significant, trend remained after additional adjustment for other
known CVD risk factors, with RRs of 1.0, 0.75, 0.83, 0.80, and 0.85 (95% CI for
extreme quintiles: 0.61, 1.17). After excluding participants with a
self-reported history of diabetes, hypertension, or high cholesterol at
baseline, the multivariate-adjusted RR was 0.45 when extreme quintiles were
compared (95% CI: 0.22, 0.91; P: for trend = 0.09). Higher fruit and vegetable
intake was also associated with a lower risk of MI, with an adjusted RR of 0.62
for extreme quintiles (95% CI: 0.37, 1.04; P: for trend = 0.07).
Conclusion: These data suggest that higher intake of fruit and
vegetables may be protective against CVD and support current dietary guidelines
to increase fruit and vegetable intake.
Liu S, Manson JE, Stampfer MJ, et al
Am J Public Health. 2000;90(9):1409-1415
Objectives:
This study examined the association between intake of whole vs refined grain
and the risk of type 2 diabetes mellitus.
Methods: We used a food frequency questionnaire for repeated
dietary assessments to prospectively evaluate the relation between whole-grain
intake and the risk of diabetes mellitus in a cohort of 75,521 women aged 38 to
63 years without a previous diagnosis of diabetes or cardiovascular disease in
1984.
Results: During the 10-year follow-up, we confirmed 1879
incident cases of diabetes mellitus. When the highest and the lowest quintiles
of intake were compared, the age and energy-adjusted relative risks were 0.62
(95% confidence interval [CI] = 0.53, 0.71, P trend < .0001) for whole
grain, 1.31 (95% CI = 1.12, 1.53, P trend = .0003) for refined grain, and 1.57
(95% CI = 1.36, 1.82, P trend < .0001) for the ratio of refined- to
whole-grain intake. These findings remained significant in multivariate
analyses. The findings were most evident for women with a body mass index
greater than 25 and were not entirely explained by dietary fiber, magnesium,
and vitamin E.
Conclusions: These findings suggest that substituting whole-
for refined-grain products may decrease the risk of diabetes mellitus.
Liu S,
Manson JE, Stampfer MJ, et al
JAMA. 2000;284(12):1534-1540
Context: Although increased intake of grain products has been recommended to
prevent cardiovascular disease (CVD), prospective data examining the relation
of whole grain intake to risk of ischemic stroke are sparse, especially among
women.
Objective: To examine the hypothesis that higher whole grain
intake reduces the risk of ischemic stroke in women.
Design, Setting, and Participants: A prospective cohort of
75,521 US women aged 38 to 63 years without previous diagnosis of diabetes
mellitus, coronary heart disease, stroke, or other CVDs in 1984, who completed
detailed food frequency questionnaires (FFQs) in 1984, 1986, 1990, and 1994,
and were followed up for 12 years as part of the Nurses' Health Study.
Main Outcome Measure: Incidence of ischemic stroke, confirmed
by medical records, by quintile of whole grain intake according to FFQ
responses.
Results: During 861,900 person-years of follow-up, 352
confirmed incident cases of ischemic stroke occurred. We observed an inverse association
between whole grain intake and ischemic stroke risk. The age-adjusted relative
risks (RRs) from the lowest to highest quintiles of whole grain intake were
1.00 (referent), 0.68 (95% confidence interval [CI], 0.49-0.94), 0.69 (95% CI,
0.51-0.95), 0.49 (95% CI, 0.35-0.69), and 0.57 (95% CI, 0.42-0.78; P =.003 for
trend). Adjustment for smoking modestly attenuated this association (RR
comparing extreme quintiles, 0.64; 95% CI, 0.47-0.89). This inverse association
remained essentially unchanged with further adjustment for known CVD risk
factors, including saturated fat and trans fatty acid intake
(multivariate-adjusted RR comparing extreme quintiles, 0.69; 95% CI,
0.50-0.98).
The
inverse relation between whole grain intake and risk of ischemic stroke was
also consistently observed among subgroups of women who never smoked, did not
drink alcohol, did not exercise regularly, or who did not use postmenopausal
hormones. No significant association was observed between total grain intake
and risk of ischemic stroke.
Conclusions: In this cohort, higher intake of whole grain
foods was associated with a lower risk of ischemic stroke among women,
independent of known CVD risk factors. These prospective data support the
notion that higher intake of whole grains may reduce the risk of ischemic
stroke.
Jacobs DR, Pereira MA, Meyer KA, Kushi LH
J Am Coll Nutr. 2000;19(3 Suppl):326S-330S
Background:
Inconsistencies in epidemiologic findings relating grain fiber to chronic
disease may be explained by differentiating nutrient-rich fiber derived from
whole grain vs. nutrient-poor fiber derived from refined grain.
Objective: Given that phytochemicals are most varied and abundant
in the outer layers of grains, we tested the hypothesis that whole grain fiber
consumption is associated with a reduced mortality risk in comparison to a
similar amount of refined grain fiber.
Design: 11,040 postmenopausal women enrolled in the Iowa
Women's Health Study, matched on total grain fiber intake, but differing in the
proportion of fiber consumed from whole vs. refined grain, were followed from
baseline in 1986 through 31 December, 1997, during which time 1,341 deaths
occurred in 124,823 observed woman-years.
Results: After multivariate adjustment in proportional hazards
regression, women who consumed on average 1.9 g refined grain fiber/2,000 kcal
and 4.7 g whole grain fiber/2,000 kcal had a 17% lower mortality rate (RR=0.83,
95% CI=0.73-0.94) than women who consumed predominantly refined grain fiber:
4.5 g/2,000 kcal, but only 1.3 g whole grain fiber/2,000 kcal.
Conclusion: Inferences from studies that have reported
associations between grain fiber intake and morbidity or mortality may be
limited by not differentiating fiber sources. Future studies should distinguish
fiber from whole vs. refined grains. Public health policy should differentiate
whole grains from refined, and recommend increased consumption of the former.
Pereira MA, Pins JJ
Curr Atheroscler Rep. 2000;2(6):494-502
Recently
reported experimental studies offer insight into the various mechanisms through
which dietary fiber may reduce the risk of cardiovascular disease (CVD) in
humans. Although most work has focused on traditional risk factors, studies
have begun to explore less studied areas of risk such as fibrinolysis.
Epidemiologic results have consistently demonstrated inverse associations
between dietary fiber, particularly cereal fiber and whole grain foods, and the
development of CVD morbidity and mortality. These associations have been
observed in both men and women and are not accounted for by potential
confounders such as other dietary and lifestyle factors; nor can they be fully
explained by body habitus, antioxidants, and other nutrients found in
fiber-rich foods. The evidence to date supports clear recommendations for a
diet based on fiber-rich foods.
Gronbaek M, Becker U, Johansen D, et al
Ann Intern Med. 2000;133(6):411-419
Background:
Although the J-shaped relation between alcohol intake and mortality has been
reproduced in many large cohort studies, the question of whether the effects of
beer, wine, and spirits differ remains controversial.
Objective: To examine the relation between intake of different
types of alcohol and death from all causes, coronary heart disease, and cancer.
Design: Pooled cohort studies in which intake of beer, wine,
and spirits; smoking status; educational level; physical activity; and body
mass index were assessed at baseline.
Setting: Copenhagen, Denmark.
Participants: 13 064 men and 11 459 women 20 to 98 years of
age.
Measurements: Number of deaths and time to death from all
causes, coronary heart disease, and cancer during follow-up.
Results: During 257 859 person-years of follow-up, 4833
participants died. J-shaped relations were found between total alcohol intake
and mortality at various levels of wine intake. Compared with nondrinkers,
light drinkers who avoided wine had a relative risk for death from all causes
of 0.90 (95% CI, 0.82 to 0.99) and those who drank wine had a relative risk of
0.66 (CI, 0. 55 to 0.77). Heavy drinkers who avoided wine were at higher risk
for death from all causes than were heavy drinkers who included wine in their
alcohol intake. Wine drinkers had significantly lower mortality from both
coronary heart disease and cancer than did non-wine drinkers (P = 0.007 and P =
0.004, respectively).
Conclusion: Wine intake may have a beneficial effect on
all-cause mortality that is additive to that of alcohol. This effect may be
attributable to a reduction in death from both coronary heart disease and
cancer.
Selmer RM, Kristiansen IS, Haglerod A, et al
J Epidemiol Community Health. 2000;54(9):697-702
Study Objective: The aim was to estimate health and economic consequences of
interventions aimed at reducing the daily intake of salt (sodium chloride) by 6
g per person in the Norwegian population. Health promotion (information
campaigns), development of new industry food recipes, declaration of salt
content in food and taxes on salty food/subsidies of products with less salt,
were possible interventions.
Design: The study was a simulation model based on present age
and sex specific mortality in Norway and estimated impact of blood pressure
reductions on the risks of myocardial infarction and stroke as observed in
Norwegian follow up studies. A reduction of 2 mm Hg systolic blood pressure
(range 1-4) was assumed through the actual interventions. The cost of the
interventions in themselves, welfare losses from taxation of salty
food/subsidising of food products with little salt, cost of avoided myocardial
infarction and stroke treatment, cost of avoided antihypertensive treatment,
hospital costs in additional life years and productivity gains from reduced
morbidity and mortality were included.
Results: The estimated increase in life expectancy was 1.8
months in men and 1.4 in women. The net discounted (5%) cost of the
interventions was minus $118 millions (that is, cost saving) in the base case.
Sensitivity analyses indicate that the interventions would be cost saving
unless the systolic blood pressure reduction were less than 2 mm Hg,
productivity gains were disregarded or the welfare losses from price
interventions were high.
Conclusion: Population interventions to reduce the intake of
salt are likely to improve the population's health and save costs to society.
Weaver CM
Am J Clin Nutr. 2000;72(2 Suppl):579S-84S
Dietary calcium and physical activity have been
independently, but inconsistently, associated with the development of increased
peak bone mass and reduced bone loss later in life. An examination of the
literature points to important effects of dietary calcium on bone health.
During the development of peak bone mass, calcium intakes of < 1 g/d are
associated with lower bone mineral density. At intakes approaching calcium
requirements, physical activity is a more important predictor of bone mineral
density than is calcium intake. In studies of postmenopausal women, calcium
intakes of 1 g (25 mmol/d) appear to be necessary to effect a positive impact
of exercise on bone mineral density in the spine. Calcium intakes recommended
for protecting bone health appear to be adequate to protect against other
disorders with
an
etiology that includes inadequate dietary calcium. Calcium requirements as
modified by physical activity need to be determined for each population
subgroup according to sex, age, race, and cultural environment.
Manore MM
Am J Clin Nutr. 2000;72(2 Suppl):598S-606S
Because
exercise stresses metabolic pathways that depend on thiamine, riboflavin, and
vitamin B-6, the requirements for these vitamins may be increased in athletes
and active individuals. Theoretically, exercise could increase the need for
these micronutrients in several ways: through decreased absorption of the
nutrients; by increased turnover, metabolism, or loss of the nutrients; through
biochemical adaptation as a result of training that increases nutrient needs;
by an increase in mitochondrial enzymes that require the nutrients; or through
an increased need for the nutrients for tissue maintenance and repair.
Biochemical evidence of deficiencies in some of these vitamins in active
individuals has been reported, but studies examining these issues are limited
and equivocal. On the basis of metabolic studies, the riboflavin status of
young and older women who exercise moderately (2.5-5 h/wk) appears to be poorer
in periods of exercise, dieting, and dieting plus exercise than during control
periods. Exercise also increases the loss of vitamin B-6 as 4-pyridoxic acid.
These losses are small and concomitant decreases in blood vitamin B-6 measures
have not been documented. There are no metabolic studies that have compared
thiamine status in active and sedentary persons. Exercise appears to decrease
nutrient status even further in active individuals with preexisting marginal
vitamin intakes or marginal body stores. Thus, active individuals who restrict
their energy intake or make poor dietary choices are at greatest risk for poor
thiamine, riboflavin, and vitamin B-6 status.
Tseng M,
DeVillis R
Ann Epidemiol. 2000;10(7):481-482
Purpose:
Underlying the diversity and changeability of US eating habits are fundamental
dietary patterns shaped by common sociohistorical experiences. Currently,
little is known of what patterns exist or their associations with
sociodemographic/lifestyle factors. We examined these issues in third National
Health and Nutrition Examination Survey data.
Methods: Analyses were based on 5,794 US-born, white
participants. Interviews included a 60-item food frequency questionnaire (FFQ)
and questions on sociodemographics and health behaviors. Dietary patterns were
identified by principal components analysis on FFQ responses. Component scores
representing intake level of each pattern were dichotomized at the median.
Logistic regression analysis was used to estimate odds ratios (OR) and 95%
confidence intervals (CI).
Results: We identified two primary dietary patterns-a
"western" pattern characterized by processed and red meats, eggs,
potatoes, and refined grains, and a "prudent" pattern characterized
by cruciferous vegetables, greens, carrots, salads, and fresh fruits. The two
patterns occurred across geographic regions and in both women and men. After
age- and sex-adjustment, the "western" diet was associated with rural
residence (OR = 1.9, 95% CI 1.7-2.2), working class status (OR = 1.4, 95% CI
1.2-1.6), and lack of high school completion (OR = 1.6, 95% CI 1.4-1.8). The
"prudent" diet was associated with high school completion (OR = 2.8,
95% CI 2.5-3.3) and behaviors reflecting greater health awareness, such as
daily physical activity (OR = 2.0, 95% CI 1.8-2.2), non-smoking (OR = 2.1, 95%
CI 1.8-2.4), and supplement use (OR = 1.8, 95% CI 1.6-2.0).
Conclusions: The two dietary patterns resemble those found in
previous US studies. Findings regarding correlates agree with social histories
describing the emergence of those patterns. Principal components analysis is
potentially useful for identifying fundamental dietary patterns for future
investigations of diet-disease associations.
Dixon LB, Sundquist J, Winkleby M
Am J Epidemiol. 2000;152(6):548-557
As
Mexican-American women and men migrate to the United States and/or become more
acculturated, their diets may become less healthy, increasing their risk of
cardiovascular disease. Data from the Third National Health and Nutrition
Examination Survey (1988-1994) were used to compare whether energy, nutrient,
and food intakes differed among three groups of Mexican-American women (n =
1,449) and men (n = 1,404) aged 25-64 years: those born in Mexico, those born
in the United States whose primary language was Spanish, and those born in the
United States whose primary language was English. Percentages of persons who
met the national dietary guidelines for fat, fiber, and potassium and the
recommended intakes of vitamins and minerals associated with cardiovascular
disease were also compared. In general, Mexican Americans born in Mexico
consumed significantly less fat and significantly more fiber; vitamins A, C, E,
and B6; and folate, calcium, potassium, and magnesium than did those born in
the United States, regardless of language spoken. More women and men born in
Mexico met the dietary guidelines or recommended nutrient intakes than those
born in the United States. The heart-healthy diets of women and men born in
Mexico should be encouraged among all Mexican Americans living in the United
States, especially given the increasing levels of obesity and diabetes among
this rapidly growing group of Americans.