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Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, MD and * Division of Clinical Applications and Epidemiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
2To whom correspondence should be addressed. E-mail: ld120i{at}nih.gov.
| ABSTRACT |
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2 y old; and rewording to
emphasize reducing saturated fat and cholesterol intakes. The shift in
emphasis includes the terminology moderate fat, which
replaces the phrasing low fat. National data about the
food supply, the populations dietary intake, knowledge, attitudes and
behaviors, and nutritional status indicators (e.g., serum cholesterol
levels) related to dietary fats help to monitor nutrition and health in
the population. Experts consider that national data, although not
without limitations, are sufficient to conclude that U.S. intakes of
fats, as a proportion of energy, have decreased. The lower intakes of
saturated fat and cholesterol are consistent with decreases in blood
cholesterol levels and lower rates of coronary mortality over the past
30 years. Strategies are needed and some are suggested, to further
encourage the population to achieve a dietary pattern that is low in
saturated fat and cholesterol and moderate in total fat. Other
suggestions are offered to improve national nutrition monitoring and
surveillance related to the guideline.
KEY WORDS: cardiovascular cholesterol dietary fat dietary guideline saturated fat
| INTRODUCTION |
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| Dietary fats and chronic disease risk |
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The elucidation of the basic relation between diet and blood lipids
culminated in the seminal studies of Keys et al. (7)
and
Hegsted et al. (8)
. These two nutrition scientists
constructed equations to quantify the changes in blood total
cholesterol produced by dietary change. In brief, SFA raise serum
cholesterol twice as much as polyunsaturated fatty acids (PUFA) lower
it. These equations remain reasonably predictive of the serum
cholesterol response of populations to shifts in diet
(12)
.
More than four decades ago, a population study report compared the
diet, serum cholesterol and coronary heart disease (CHD) rates in the
U.S. with those in other countries (13)
. Positive
relationships were noted among dietary patterns, rich in total fat and
SFA, and serum cholesterol and CHD mortality rates within and across
populations. In 1970, the Seven Countries Study confirmed and extended
these findings (14
,15)
.
Evidence for the effectiveness of blood cholesterol-lowering
therapy in reducing the incidence of heart attack and other clinical
sequelae of CHD was first provided in January 1984 with the Lipid
Research Clinics Coronary Primary Prevention Trial (16)
,
and subsequently by numerous large, randomized trials using a variety
of cholesterol-lowering diets, drugs and other interventions
(17
18
19)
.
By the 1980s, several authoritative histories reflected scientific
agreement that supported a relation between dietary total fat and
certain types of cancer, especially cancer of the breast, colon and
prostate (20)
. Evidence also suggested an association
between dietary fat and the development of obesity in animals and
possibly in humans (19)
.
| Emergence of dietary guidance on fat intake |
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A recent historical account of the development of the Dietary
Guidelines, presented by Michael McGinnis at a Dietary Guidelines
Advisory Committee (DGAC) meeting in 1998, suggests that the Dietary
Goals for the U.S., and in particular their quantified nutrient
targets, prompted the two departments, the USDA and the Department of
Health and Human Services (DHHS), to consider descriptive (but not
numerical) Dietary Guidelines for the American people
(23)
.
Several national and expert scientific committee activities have
influenced Federal recommendations regarding advice to lower intake of
total fat, SFA and cholesterol. These include the consensus of a Task
Force sponsored by the American Society for Clinical Nutrition that
evaluated the strength of evidence for the relationships among dietary
fats, dietary cholesterol and heart disease (24)
, the
furor created by the National Academy of Science Report on
Healthful Diets (25)
, national prevention goals
disseminated through the DHHS Health Objectives for the Nation
(26
27
28)
, the National Cholesterol Education Program
(NCEP) (29)
, The Surgeon Generals Report on
Nutrition and Health (17)
, the National Research
Councils report on Diet and Health: Implications for Chronic
Disease Risk (19)
and the Nutrition Labeling and
Education Act (NLEA) of 1990. In addition, the nutrition-related
research of the NIH on diet and chronic diseases has continued to grow
exponentially in concert with federal efforts to reduce the nations
burden of chronic diseases. Simultaneously, consumers have shown an
ever-increasing interest in nutrition and health. These activities
are interwoven and interact; it is not possible to separate the
independent effect of each one.
Table 1
summarizes how the recommendations for dietary fats have changed over
time. Anumber of perspectives on the history of these recommendations
are available (30
31
32
33
34
35
36
37
38
39)
.
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| Dietary Guidelines for Americans: Advice on dietary fats |
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In this paper, the primary sources of the rationale for changes in the
guideline are the DGAC reports (40)
and the
transcripts of the public meetings (23)
.
| Major changes in the guideline for dietary fats |
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Numerical goals for dietary fats.
The 1990 DGAC report indicates agreement with numerical goals for dietary fats with the conclusion that widely based population data supplemented the evidence from clinical trial research, which at the time had been conducted predominantly in white males. The totality of the evidence was such that the goals were considered to be appropriate for the total population, not just persons at risk for heart disease.
The 1990 DGAC concluded that the potential benefits in reducing risk of
CHD and some types of cancer by reduction in total fat, SFA and
cholesterol were sufficient to support numerical goals for all healthy
adults. The numerical goals for total fat and SFA related to the two
food components considered to be of greatest significance to the health
of Americans. The goals adapted, those of the National Research
Council, the NCEP, and by history, the AHA, are total fat
30%
of energy and SFA < 10% of energy.
The 1990 DGAC noted that the exact numerical goals reflect both science and pragmatism. The numerical goal for SFA is based on epidemiologic evidence that populations with such intakes have less CHD and on a large body of evidence from many types of studies that reducing intake of SFA lowers blood cholesterol and CHD risk. The 1990 DGAC report noted the virtually unanimous agreement for SFA < 10% of energy as the appropriate level. Less than 10% of energy is advised for practicality of U.S. dietary habits, consistency with other expert recommendations and comprehensibility if dietary guidance is provided.
The numerical goal for total fat is based on expected beneficial effects. A reduction of total fat would facilitate reduction of SFA and benefit CHD reduction; a limit on total fat was thought to be useful to reduce the risk of some types of cancer and help manage energy intake, thus helping to curb overweight and obesity.
The policy to base recommendations on reduction of fat intake as a
proportion of energy intake, rather than absolute intake (g/d), is
consistent with historical practice. In 1968, an AHA report stated that
the desirable intake of fat for the general U.S. population was
3035% of energy, of which one third was to be SFA, one third
monounsaturated fatty acids (MUFA) and one third PUFA
(22)
. In subsequent statements, the Nutrition Committee of
the AHA recommended that SFA be < 10% of total energy, that PUFA
be < 10% of total energy and the remainder be supplied by MUFA
(31)
. Establishing dietary guidance for fat intake as a
proportion of energy also follows clinical dietetics, e.g., dietary
management of hyperlipoproteinemia (41)
. There was no
historical precedence to suggest that the DGAC considered recommending
grams of fat per day.
A recommended numerical goal for dietary cholesterol has been suggested indirectly since 1995 by reference to the Daily Value (DV) on the Nutrition Facts label (i.e., 300 mg/d). The 2000 DGACs public discussion and report note that SFA and cholesterol occur together in the foods that are major sources of SFA.
Age for use of numerical goals in children.
A second major change in the guideline is the advice on the
age in childhood at which the numerical recommendations of dietary fats
are relevant. The 1980 and 1985 Dietary Guidelines are
generally considered appropriate for all healthy Americans. The 1990
edition is the first to state that the Dietary Guidelines
are advice for healthy Americans
2 y old, not for younger children
and infants. The guideline on dietary fats restates the
introduction, saying that the goals for fats are not for children <2 y
old.
The 1990 DGAC report notes the decision to use the numerical goals for
children, stating that evidence indicates that children
2 y old can
grow and develop normally when consuming 30% of energy as fat. The
DGAC concluded from the body of evidence that health advantages would
probably occur among children through guidance for low fat (
30% of
energy) dietary patterns without being unduly restrictive. Thus, the
DGAC recommended flexibility in applying the numerical goals to
children, recognizing the importance of a diet to support growth and
the need to develop acceptability for a lower fat diet among children.
The evidence to support a reduced intake of fats, especially SFA and
cholesterol, is documented in the NCEP report that focuses on the
treatment of high blood cholesterol levels in children
(42)
. Members of the 1990 DGAC who represented the
pediatric community were knowledgeable about this report. The major
points include the following: 1) entire populations have low
intakes of SFA and cholesterol and total fat, and these populations
have low levels of serum cholesterol and CHD; 2) the
children are healthy and intelligent; 3) CHD risk factor
levels track from childhood into adulthood; and 4) food
purchases and preparation feed the whole family, i.e., children and
adults. Also, the 1990 DGAC report noted that the NCEP was preparing
recommendations for children, and that new legislation required the
USDA and DHHS to develop a publication, "Nutrition Guidance for Child
Nutrition Programs," and apply this guidance to child nutrition
programs.
In 1995 the DGAC report stated that in keeping with recommendations by
other authorities, the guideline applied to children
2 y
old. For logical and practical reasons, the DGAC recommended gradual
adoption of the guideline from age 2 to 5 y, so that by
the time children were in school, they should be consuming diets that
follow the Dietary Guidelines. The 1995 DGAC report also
stated that the advice was appropriate for health reasons and would
enable uniformity in directions for National School Lunch Programs. The
report noted a recent study, the Dietary Intervention Study in
Children, indicating no adverse effect among children, ages 810 y, of
a diet that contained 28.5% of energy from total fat, 10% from SFA
and 90 mg cholesterol/1000 kcal (43)
.
The 2000 guideline changes the recommendation back to the
advice of 1990, clearly stating that the recommended intakes of dietary
fats apply to children beginning at age 2 y. The DGAC concludes
that recent studies among children ages 810 y (43
,44)
and children ages 736 mo (45)
support the safety of
diets that are low in SFA and cholesterol for children who are
2 y
old,. Views in support and in dispute of this recommendation have been
expressed (46
47
48
49
50
51)
.
Statement wording.
The third major change in the guideline is the statement wording. The 2000 language is the first national recommendation to prioritize type of fat over amount of fat. The wording, choose a diet low in saturated fat and cholesterol and moderate in total fat, reflects the DGACs conclusion that for total fat, the evidence of causality of chronic disease is less conclusive than it is for SFA, cholesterol and CHD.
The 2000 DGAC report provides several explanations for the word
moderate in total fat vs. low in total fat.
First, a change in perception in the meaning of the two terms is
recognized. The report suggests that the term high fat
refers to total fat of
40% of energy, moderate fat to
30% and low fat to
20%. Second, the DGAC cites
evidence that suggests that low fat diets (20% of energy) are by
necessity high in carbohydrate and may cause an unfavorable pattern
characterized by low HDL and elevated triglycerides. Also, an excessive
carbohydrate intake might enhance postprandial response in glucose and
insulin concentrations that may predispose persons with insulin
resistance to type 2 diabetes mellitus. In contrast,
moderate fat intakes allow more unsaturated fatty acids,
which, along with low SFA, are associated with reduced risk of heart
disease. A final argument for using the word moderate fat is
to move away from an incorrect viewpoint that a low total
fat intake per se (as opposed to making additional changes
to develop healthful dietary patterns) will result in a healthful diet.
An emphasis on type of fat reflects the DGACs conclusion that the weight of evidence concerning the contribution of a high fat diet to cancer incidence is not presently sufficient to justify promoting low fat intake for the U.S. population. Also, the DGACs conclusion reflects their persuasion of the theory that a high percentage of fat contributes to obesity and may warrant placing a ceiling on total fat intake, but is not sufficient in itself to warrant a definitive recommendation for a low fat diet. The use of the term moderate is part of a strategy that is intended to shift the emphasis away from total fat. Whether consumers make appropriate food choices reflecting this subtle shift in message remains to be seen.
| Other message changes in the guideline |
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| SURVEILLANCE METHODS TO ASSESS THE GUIDELINE |
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Food supply data
Estimates of foods and nutrients available for consumption from
the food supply, collected by the USDA since 1909, are updated and
published annually in the U.S. Food and Nutrition Supply Series
(53)
. Annual estimates of foods available for consumption
are determined from the difference between the total available supply,
which is the sum of production, inventories from the past year, and
imports of food, and foods that are exported, used by industry or as
farm inputs, or in the current year-end inventories
(55)
. These estimates, calculated in pounds per person per
year, are often referred to as food disappearance data because they
represent the disappearance of food into the market place. Estimates of
nutrients from food available for consumption are calculated by
multiplying the nutrient value per pound by the quantity of each food
(in pounds) and summing across all foods. These food and nutrient data
are used as proxies to estimate human consumption. However, the data
overestimate consumption because they include inedible refuse (e.g.,
bones), ingredients in processed foods that are exported (e.g., soft
drinks, baked goods, cereal products), and amounts lost in processing,
marketing or spoilage, or foods thrown away or fed to pets
(55)
.
The use of food supply data to monitor fat intakes of the population
has been strongly cautioned, primarily because of the unaccounted waste
(56)
. Over the past two decades, the waste portion of fats
and oils has increased due to growth in away-from-home eating places,
in particular, fast-food places (57)
. Amounts of fat
used for frying and discarded from foodservice operations have been
estimated to be
50% (58)
. Estimations of fat intake
from food supply data are further complicated by the production of fat
substitutes made from fats (e.g., olestra made from vegetable oils)
that are consumed but not digested (59)
. Recently, the
USDA has developed methods to adjust the data for spoilage and other
waste including retail, food service and consumer losses, changes in
weight due to cooking and the discarding of nonedible food parts to
more closely reflect intake data (60)
.
Survey data of food and nutrient intake
Several major surveys help monitor food and nutrient intakes
(Table 2
). The primary dietary assessment tool used to monitor intake is the
24-h dietary recall. Multiple 24-h recalls are considered to be the
"gold standard" for nutrition monitoring (61)
and will
produce stable estimates of mean nutrient intakes from groups of
individuals. Provided that the sample size is large enough, single 24-h
recalls will also produce reasonably accurate estimates of mean
nutrient intakes from groups of individuals (62)
. However,
if additional 24-h recalls have been collected from a representative
subsample of participants, methods that adjust for the
within-person day-to-day variation in dietary intake from one 24-h
recall are encouraged (63)
. Such methods have been applied
to analyses of 1-d dietary data from the Third National Health and
Nutrition Examination Survey (NHANES III) using data from a second 24-h
recall collected from
5% of participants (64)
.
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In addition, 24-h recalls have limitations related to systematic bias
in underreporting of energy intake (67)
and possibly
underreporting of foods containing fat (68)
. Methods have
been developed to assess the degree of underreporting in national
survey data (69
,70)
, allowing for comparisons of dietary
intakes of low energy reporters with those of others (71)
.
Measuring change in dietary intakes is further complicated by
differences in procedures and databases used in national surveys
(62
,72)
. Interpretation of change in dietary intakes
across national surveys requires knowledge of survey design
characteristics, i.e., sampling frames, response rates of the surveys,
age ranges of respondents, number of days of dietary data collection,
days of the week selected for dietary data collection, and interviewing
and coding methods. Comparisons of fat intakes are particularly
affected by the content of the food and nutrient databases. For
example, USDA and manufacturers composition data were used in NHANES
I and II, whereas an updated version of the USDA database with
increased numbers of ethnic and brand name foods was used in NHANES III
(73)
. Also, the procedure for estimating fatty acid intake
has changed. The 19771978 National Food Consumption Survey nutrient
composition tables included all PUFA, whereas NHANES I and II nutrient
composition tables included the major PUFA, linoleic acid
(12
,74)
. Differences in survey estimates of dietary
cholesterol may reflect changes in the cholesterol content of eggs as
well as improvements in analytic technology to assess cholesterol
content of animal products in the late 1980s (75)
.
Improvements in measurements of intake (e.g., including the
contribution of alcohol to energy intake, using additional probes to
improve food recall) are also factors to consider when evaluating
trends in dietary data expressed as a percentage of total energy. Many
of these differences should be resolved with one national survey of
dietary intake administered on a continuous basis (76)
.
In 2000, the guideline for dietary fats recommends that
consumers also reduce their intake of trans-fatty acids;
these were not available in the national food composition database
until recently. In 1995, the USDA released a special data set that
provides g/100 g trans-fatty acids in 214 foods
(77)
. These foods are major sources of
trans-fatty acids in the U.S. population. Designated food
codes allow linkage to the national surveys of dietary intake
(78)
. Such analyses are limited by the number of foods
that have values for trans-fatty acids and require
judgements when matching codes of these 214 foods to codes of many
similar, but not identical, foods in the national surveys. However,
previous estimates of trans-fatty acid intake in the U.S.
are from Food Supply Data or food frequency data and are less precise.
Survey data of knowledge, attitudes, and behaviors
The Diet and Health Knowledge Survey (DHKS), administered to a
subsample of participants in both the 19891991 Continuing Survey of
Food Intakes by Individuals (CSFII) and the 19941996 CSFII, provides
information about consumers knowledge, attitudes and behaviors
related to total fat, SFA and cholesterol (79
,80)
.
Respondents were asked whether they were aware of health problems
related to fat, SFA and cholesterol, how important it is to
avoid too much fat, SFA and cholesterol (which was changed to how important it is to choose a diet low in fat, SFA and cholesterol when the wording of the guideline changed in 1990), and whether they thought their diets should be lower or higher
or were just right in terms of the amounts of fat, SFA and cholesterol.
Survey data of nutritional status indicators
NHANES I, II and III provide national data on nutritional status
and health indicators, such as serum cholesterol and lipoprotein
levels. Methodologies used to measure serum lipids and lipoproteins
differ across surveys, but all have been standardized to the criteria
of the Centers for Disease Control and Prevention (CDC) or the
CDC-National Heart, Lung, and Blood Institute Cholesterol
Standardization Program (81)
.
| RESULTS FROM SURVEILLANCE DATA |
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Dietary intake data from the 19941996 CSFII provide current
population estimates of dietary fats. These 1-d dietary data show mean
intake of total fat as 32.8% and SFA as 11.3%, as a proportion of
energy, and mean cholesterol intake as 256 mg for all participants
(Table 3
). Absolute mean intakes of total fat and SFA intake are
74 and 26 g, respectively (Table 3)
. These values correspond to
about half of the estimated consumption derived from food supply data
in 1994 (i.e., 159 g of total fat and 52 g of SFA)
(Table 4A
). This is not surprising, given that at least half of fats and
oils in the U.S. food supply are estimated to be discarded before
consumption (58)
. Dietary data from the 19891991 CSFII,
in combination with USDA food data on trans-fatty acids,
show the mean intake of trans-fatty acids as 5.3 g,
accounting for 7.4% of total fat and 2.6% of total energy, for
participants
3 y old (Table 5
).
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Food supply data from 1970 to 1996 provide information about
changes in major food sources of dietary fats, including meats, eggs,
dairy foods, and added fats and oils (83)
. During these
years, Americans consumed less red meat but more chicken, fish and
turkey; fewer eggs, particularly eggs purchased in cartons in the
grocery store, but more egg products used in processed foods or in the
form of nonfat, no-cholesterol liquid egg substitutes; less milk,
particularly whole milk, despite increases in fat-free, light and
reduced fat milk; more yogurt (predominantly lower fat), but also more
higher fat dairy foods including cheese and fluid cream; and more fats
and oils, particularly salad and cooking oils, although a recent slight
decrease has been seen.
Food supply data also suggest that Americans have consumed more total
fat and less SFA and cholesterol since the early 1900s, reflecting an
increase in production and use of vegetable oils and a decrease in
animal fats (Table 4AA
) (84)
. Although these
trends continue from 1970 to 1994, the increase in grams of total fat
and the decrease in grams of SFA are much less than that observed from
1909 to 1970. Food supply data from 19701996, adjusted for waste and
other losses, show that Americans have consumed increasingly more added
fats and oils relative to the Food Guide Pyramid recommendations (Table 4B
) (60)
.
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Two-day dietary data from 19941996 CSFII show that approximately
one third of adult men and women met the dietary goals for total fat
and SFA, whereas more than two thirds met the DV for cholesterol
(Table 6A
). Data from the 19941996 DHKS show that the majority of adult
respondents thought their diet was "too high" in fat but "about
right" in SFA and cholesterol content, indicating that consumers may
be able to judge their total fat and cholesterol intakes but have
difficulty evaluating their SFA intakes. The majority of adult
respondents also perceived the guideline of "choose a diet
low in fat, saturated fat, and cholesterol" as "very important"
(Table 6B
).
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It is important to note that differences between the two DHKS surveys
may be due to differences in sample populations and sample weighting
(i.e., 19891991 respondents were household main meal-planner/preparers vs. 19941996 respondents who were individuals
20 y old), differences in question wording and/or response scales,
and differences in methodologies (i.e., the 19891991 CSFII included three consecutive days of dietary intake using a 1-d recall and a 2-d record; the 19941996 CSFII included two nonconsecutive days of
dietary intake from two 24-h recalls) (85)
. It is also
possible that changing attitudes about the importance of total fat
intake reflect a shift in scientific thinking as well as conflicting
media reports that total fat intake is not as important as was
previously considered. Conflicting health messages are often
disseminated with overinterpretation of the data from each research
finding, rather than with a perspective of how the new finding fits
with the totality of research on nutrition and health.
Survey data of nutritional status indicators
In NHANES III, the mean serum cholesterol level for adults,
20 y
old, was 206 mg/dL, with 21% having concentrations > 240 mg/dL
(defined as high blood cholesterol according to the NCEP)
(28)
. Approximately 41% of all deaths are attributed to
cardiovascular disease in current data (86)
. Since the
1940s, cardiovascular disease continues to be the leading cause of
death in the U.S. population.
Age-adjusted mean serum total cholesterol levels decreased by 1217
mg/dL among women and men, ages 2074 y, who were examined in one of
four separate national surveys conducted by NCHS between 1960 and 1991
(87)
(Fig. 2
). Age-adjusted LDL cholesterol levels decreased by an average of 8
mg/dL and age-adjusted HDL cholesterol levels increased by an
average of 1 mg/dL, according to data from adults who participated in
NHANES II 197680 and NHANES III, phase I (19881991). Mean serum
total cholesterol levels also decreased in adolescents, ages 1217 y,
between 1966 and 1994 (88)
. Population decreases in
age-adjusted serum total and LDL cholesterol levels parallel
changes in coronary mortality rates in the U.S.A., which decreased by
54% between 1963 and 1990 (87)
.
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| STRATEGIES FOR IMPROVEMENT |
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Although the majority of Americans report that it is important to
reduce their fat intake, beliefs and knowledge often do not translate
into behavior change (90)
. Many other factors influence
food choices and eating behavior (91)
. People choose foods
according to personal preferences (taste in particular), cultural
values, what they learned or were exposed to in childhood, what is
available in the community and cost. Peoples food choices are also
influenced by their family and friends, and especially by the media.
Advertisements, developed by marketing experts to persuade consumers of
food appeal, are widely disseminated. In 1997, the food industry spent
$11 billion on advertising: $7.1 billion by food manufacturers, $3.1
billion by restaurants and $860 million by food retailers
(92)
. Food manufacturers spent 44.4% of their advertising
budget on prepared convenience foods, confectionery and snacks, and
bakery goods compared with only 2.2% on fruits, vegetables, grains and
beans. For perspective, the budget to develop the Food Guide Pyramid
was
$1 million (93)
. The annual budget of the
Five-A-Day for Better Health program, aimed at increasing consumption
of fruits and vegetables, is
$5 million (94)
.
The proportion of meals and snacks eaten away from home has increased
from 16% in 19771978 to 27% in 1995 (95)
. The
consumption of foods prepared away from home often results in less
control over the amount of fat eaten. Busy people may not find it
convenient, nor make it a priority to select food choices that are low
in SFA and cholesterol. Take-out foods generally do not have a
Nutrition Facts label so consumers rarely know the content of SFA,
cholesterol, trans-fatty acids or total fat.
Consumers food choices are also affected by federal policies that may
be internally inconsistent. For example, the USDA is responsible for
both dietary guidance policy aimed at health promotion and economic
policy that provides incentives to enhance production of animal food
commodities (96)
.
Strategies for meeting the guideline
Nutrition education is the common strategy used to combat barriers
to dietary change at the individual level. A variety of theoretical
models or frameworks are used by educators in academia, government and
private industry to lower dietary fats (91)
. Those that
have been most successful focus on behavioral changes (90)
and incorporate self-evaluation tools, social support, contractual
agreements, principles of social marketing and increased access to
lower fat foods that taste good (91)
. Many programs teach
specific food-choice strategies such as choosing skim milk and lean
meats instead of higher fat counterparts, increasing intake of fruits,
vegetables and whole grains, and reducing portion sizes
(91)
. Many programs involve the media, schools,
work-sites and the general community (36)
. With the
increasing diversity of the U.S. population, future programs will have
to target vulnerable subgroups in culturally sensitive ways
(97
,98)
.
Several federal dietary guidance policies aim to reduce the
populations intake of SFA, cholesterol and total fat. The passage of
the NLEA in 1993 and the revised Nutrition Facts label, jointly agreed
upon by the Food and Drug Administration (FDA) and USDA, comprise a
daily source of information for consumers (99)
. Nutrient
content and disease-specific health claims related to dietary fat
have been approved by the FDA and appear on many food labels
(99)
. A USDA policy to require the Nutrition Facts label
on packaged meat and poultry products was announced at the 2000
National Nutrition Summit in Washington, DC (100)
. The
inclusion of the content of trans-fatty acids with SFA on
the Nutrition Facts label has been proposed by the FDA
(101)
. The Food Guide Pyramid, released in 1992,
demonstrates proportionality, variety and moderation of foods,
including added fats, and is widely recognized (102)
. In
1996, the National School Lunch and Breakfast Programs were mandated to
serve lunches and breakfasts that meet the guideline for
dietary fats (103)
. Several education initiatives from the
NIH have adapted diet and risk factor information that is culturally
sensitive and targeted to specific population groups. Industry has also
introduced a plethora of nonfat, low fat and fat-modified foods
intended to reduce dietary fats in the U.S. population. Although these
products are lower in fat, many of these products are not lower in
energy. Thus, dietary guidance policy that would mirror, in the U.S.
population, both the lower fat intakes of other countries and their
lower prevalence of overweight and obesity, has not succeeded.
What next steps might be encouraged?
The concepts and information that provide the foundation for the
Food Guide Pyramid must be updated to reflect current intakes and
recent Dietary Reference Intakes (104
105
106)
. In addition,
messages on types of dietary fats are not well conveyed by the Pyramid.
Consideration should be given to the design and implementation of a
project that will help consumers use the Pyramid to recognize different
types of fats and their food sources, and to choose a diet in the
market place that is low in SFA and cholesterol and moderate in total
fat in the context of the total diet. Research initiatives should be
developed to identify practices that are most effective in assisting
people with lower levels of income and education to choose diets that
reflect the guideline.
Further consideration must be given to messages or food product labels at the point of purchase (wherever the purchase) to help consumers identify foods that are low in SFA and cholesterol and compare energy content among food products. This is especially important for foods prepared away from home. Evaluation of endeavors related to recent food labeling initiatives is also warranted. For example, what do consumers understand about % DV, what refinements in the Nutrition Facts label can improve the message that type of fat is important to consider, and if implemented, what is the effect of trans-fatty acid labeling on food purchases and fat intake?
Some academic scholars provide provocative ideas for changing the
environment, such as the provision of economic incentives for the
promotion of healthful foods or placing putative taxes on
unhealthful foods (36
,96
,107)
. Such policy
would require an agreed upon and enduring definition of a
healthful food, an especially challenging task (e.g., not
all nonfat or low fat foods might be considered healthful
and vice versa, not all full-fat foods might be considered
unhealthful). Ways to modify Federal policies to enhance
public health goals have also been suggested (96
,108)
.
Lessons from community studies aimed at health promotion and risk factor reduction show that through identification and working with community leaders, healthful behavior changes occur. The challenge is to maintain healthful behaviors once the funding source no longer provides support. It may be time to reconsider research support for the development of model centers of change. These model centers could identify examples of successful change in adopting lower intakes of SFA and cholesterol and moderate intakes of total fat by diverse cultures, and measure long-term intake and health indicators.
Finally, support for research, nutrition monitoring and surveillance
must continue if we are to clarify further the relationships among
dietary components, nutrients and chronic disease. Attention must be
given to continued development of improved dietary intake methods to
assess fat intake with accuracy. Types of fat vary substantially among
and within brands of foods. Which fat is used in a food product depends
on the price of oils and fats available at the time of production, the
functional property of the fat and the requirement to show SFA content
on the Nutrition Facts label. Systematic probes and questions to
identify brand names as well as amounts of fats that consumers add to
foods are necessary to obtain accurate information regarding dietary
fats. Support for accurate and comprehensive food and nutrient
composition databases that provide data on nutrients such as
trans-fatty acids must also continue and be increased to
keep pace with the thousands of new foods introduced each year (e.g.,
16,863 were introduced in 1995) (92)
. In addition, support
for the collection of at least two independent days of dietary intake
data in national surveys is important. Multiple days of dietary data
are necessary to estimate "usual intake" in order to assess
properly the prevalence of individuals with fat intakes above the
numerical goals (63)
. Such data are critical for food
assistance, food regulatory and consumer education programs.
In conclusion, the success of dietary guidance to achieve a national dietary pattern that is low in SFA and cholesterol and moderate in total fat is dependent upon a multifaceted approach to dietary change in step with national nutritional monitoring that will facilitate analysis of what and where change is occurring and where additional resources are needed.
| APPENDIX |
|---|
|
|
|---|
The text of the guideline initially contained a dual
message about food sources of fats (Table A1
). Limited information about major food sources was accompanied by a reminder that these foods were also good sources of essential
nutrients. In 1990 and subsequently, the text of the
guideline offers suggestions to help identify the major
sources of SFA and cholesterol. Emphasis is no longer on the nutritious
quality of foods that are high in SFA and cholesterol. Instead, the
discussion promotes low fat versions of meats and dairy products.
Dietary fats and health concerns
Shifts in the explanation of the link between dietary fats and
health have occurred (Table B1
).The initial concern, the relation between dietary fats and risk of CHD,
was broadened to include an emphasis on total fat to reduce the risk of
certain cancers, and potentially to avoid greater prevalence of weight
gain and obesity. The current message returns the focus to reduction of
CHD through reduced intake of SFA and cholesterol and use of
unsaturated fatty acids within a moderate total fat intake.
Messages were dropped that tended to "medicalize" the guideline and diffuse the diet message, such as advice to have blood cholesterol measured and achieve 200 mg/dL, and the mention of multiple CHD risk factors. Also deleted were discussions about variation in blood cholesterol levels with intakes of SFA and cholesterol, and a comparison of the relative effect of SFA vs. dietary cholesterol. The intent is a change in national dietary patterns to lower the intake of SFA and cholesterol, to improve mean blood cholesterol and reduce the CHD risk of the population.
Two additional links between dietary fat and health are made in the guideline in 1995 and in 2000: an association between intakes of trans-fatty acids and (n-3) PUFA and CHD. The advice is that foods high in trans-fatty acids tend to raise blood cholesterol and that (n-3) fatty acids are being studied because of a possible association with decreased risk for heart disease in certain people.
Dietary fats and food selection/preparation
The advice about food selection and preparation has evolved into
describing choices among types of fat (Table C1
).Recent editions discuss SFA and cholesterol together, rather than make distinctions between the two food components. Although the 1995
guideline suggests using all types of fats and oils
"sparingly," current readers are advised to limit animal fats, hard margarines and partially hydrogenated shortenings. Vegetable oils are
mentioned as substitutes for SFA.
The Nutrition Facts label appears in the guideline to make
the numerical goals more understandable and useful to readers at the
point of food purchase. The % DV allows the Committees to signal a
numerical goal for cholesterol, by referencing the cholesterol DV of
300 mg, at the 2000 kcal level.
|
|
|
| FOOTNOTES |
|---|
3 The term "saturated fat" refers to saturated
fatty acids. ![]()
4 The term "dietary fats" refer to the three
fats listed in the guideline (total fat, saturated fat and
cholesterol). ![]()
5 Abbreviations used: AHA, American Heart
Association; CHD, coronary heart disease; DV, Daily Value; CSFII,
Continuing Survey of Food Intakes by Individuals; DGAC, Dietary
Guidelines Advisory Committee; DHHS, U.S. Department of Health and
Human Services; DHKS, Diet and Health Knowledge Survey; FDA, U.S. Food
and Drug Administration; MUFA, monounsaturated fatty acids; NCEP,
National Cholesterol Education Program; NHANES, National Health and
Nutrition Examination Survey; NLEA, Nutrition Labeling and Education
Act; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids. ![]()
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J. L. Wiecha, K. E. Peterson, D. S. Ludwig, J. Kim, A. Sobol, and S. L. Gortmaker When Children Eat What They Watch: Impact of Television Viewing on Dietary Intake in Youth Arch Pediatr Adolesc Med, April 1, 2006; 160(4): 436 - 442. [Abstract] [Full Text] [PDF] |
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T. C. Jenkins and M. A. McGuire Major advances in nutrition: impact on milk composition. J Dairy Sci, April 1, 2006; 89(4): 1302 - 1310. [Abstract] [Full Text] [PDF] |
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K. L. Ritzenthaler, M. K. McGuire, M. A. McGuire, T. D. Shultz, A. E. Koepp, L. O. Luedecke, T. W. Hanson, N. Dasgupta, and B. P. Chew Consumption of Conjugated Linoleic Acid (CLA) from CLA-Enriched Cheese Does Not Alter Milk Fat or Immunity in Lactating Women J. Nutr., March 1, 2005; 135(3): 422 - 430. [Abstract] [Full Text] [PDF] |
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K. Morland, S. Wing, and A. D. Roux The Contextual Effect of the Local Food Environment on Residents' Diets: The Atherosclerosis Risk in Communities Study Am J Public Health, November 1, 2002; 92(11): 1761 - 1768. [Abstract] [Full Text] [PDF] |
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