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Newsletters & Publications
| Volume
17 - Number 4 |
Winter 2000 |
COMMON ABBREVIATIONS
BMI: body mass index (kg/m2)
CAD: coronary artery disease
CHD: coronary heart disease
CHO: carbohydrate
CI: confidence interval
CVD: cardiovascular disease
ene: energy
HDL: high density lipoprotein
LDL: low density lipoprotein
Lp(a): lipoprotein (a)
MI: myocardial infarction
MUFA: monounsaturated fatty acids
NCEP: National Cholesterol Education Program
P:S: dietary polyunsaturated:saturated fat ratio
PUFA: polyunsaturated fatty acids
RR: relative risk
SFA: saturated fatty acids
TAG: triacylglycerol
VLDL: very low density lipoprotein
We all know that a healthful diet plays an
important role in protecting us against major chronic diseases.
And in an effort to assist Americans to eat more healthfully, the
USDA and Health and Human Services developed the Dietary Guidelines
for Americans, which is a compilation of healthy eating patterns.
This tool, which was first developed in 1980 has undergone regular
evaluation to insure that the recommendation is inline with current
research data. However, the efficacy of this guideline has been
untested until recently. Hu et al. tested the relationship between
adherence to the Dietary Guidelines for Americans and risk of major
chronic disease in men, than using the Nurses' Health Study (NHS)
data, McCullogh and colleagues assessed the same relationship in
women. However, these 2 studies arrived at 2 very different results
regarding the efficacy of adherence to the Dietary Guidelines for
Americans in protecting against major chronic diseases.
Using the food frequency questionnaires 67,
272 healthy women enrolled in the NHS, the researchers calculated
the Healthy Eating Index (HEI) scores ranging from 0 (worst) to
100 (best). The criteria for the HEI score was based on the frequency
of eating from all 5 food groups and restricting negative nutrients
such as fats and sodium. The mean HEI score was 64.4 in the study
cohort. This was the same HEI scores as in the CSFII subpopulation,
who were matched for age and degree of education with the NHS cohorts.
However, compared to the subjects in the NHS, the CSFII cohort
ate less vegetables, fruits, and meats. High HEI scores were associated
with overall healthier lifestyle behaviors in both cohorts. During
the 12-year follow-up, 365 cases of CVD, 5216 cases of cancer,
and 496 cases of traumatic deaths were reported. The researchers
divided individuals into quintiles based on their HEI scores. The
median HEI scores were 48, 50, 65, 75, and 80 for quintiles 1 through
5, respectively. Intakes of milk, fruits, vegetables, grains were
directly associated with higher HEI scores, while fat and sodium
were inversely related.
In relation to HEI scores, age-adjusted RR
for the highest quintile to the lowest quintile for major chronic
diseases was 0.81, 0.59 for CVD, and 0.92 for cancers. However,
when other CVD risk factors were included in the analysis, it diminished
the net beneficial effects of a higher HEI score. The multivariate
adjusted RR for major chronic diseases, CVD, and cancer were 0.97,
0.86, and 1.02, respectively, in the highest HEI score group. The
data suggest that following a healthy diet as prescribed by the
Dietary Guidelines for Americans lowered CVD risk by 14% but made
no difference in either cancer or mortality rates from major chronic
diseases.
The researchers postulated that the weak association
between following the Dietary Guidelines for Americans and less
than resounding protection against cancer, and other major chronic
diseases might have been the result of several limitations in the
design of the study. For example, HEI scores were developed to
assess nutritional quality of a 24-hour food recall rather than
for long-term dietary habits as in the case with food frequency
questionnaires used in the NHS. Also, since HEI scores were based
on the frequency of all 5 food groups, rather than specific foods,
HEI scores would be high for people eating high qualities of red
meats and refined bread products as well as someone eating lots
of whole grains, fruits and vegetables. Even though this is not
a perfect study, as a result of this study, it is possible to conclude
that the HEI score does not necessarily measure the optimal diet
to prevent major chronic diseases. And in order to help Americans
eat more healthily, HEI, the Dietary Guidelines for Americans,
and Food Guide Pyramid, "should be continue to be evaluated for
their efficacy in reducing the incidence of disease of major public
health concern."
Contrary to the NHS findings, the data from
the Health Professionals Follow-Up Study (n=44,875 males) suggested
that following a healthy dietary pattern does lower CHD risk, independent
of other CHD risk factors. For example, of the 1089 cases of both
fatal and nonfatal CHD reported during the 8 year follow-up period,
it occurred more in the subjects who followed the Western pattern
diet, which is higher in fat content and highly processed foods,
versus the prudent pattern which is high in fruits, vegetables,
fish, and poultry.
The subjects were stratified into the prudent
pattern and Western pattern based on the 131-item food frequency
questionnaires. And based on the analysis, the multivariate adjusted
RR across increasing quintiles of prudent pattern score were 1.0,
0.87, .079, 0.75, and 0.70 (95%CI: 0.56, 0.86; p for trend=0.0009).
On the other hand, the RR across increasing quintiles of the Western
pattern were 1.0, 1.21, 1.36, 1.40, and 1.64 (95% CI: 1.24, 2.17,
p for trend <0.00013). Separate analysis of the direct relationship
between Western pattern and fatal and nonfatal CHD showed that
it was much stronger for fatal CHD events.
Based on this result, Hu et al. concluded that
the 2 dietary patterns shown by the food frequency questionnaire
is a good predictor of CHD risk. And by replacing diets high in
fat and processed foods with more fruits, vegetables, fish, and
poultry, consumers should be able to lower their risk of CHD.
McCullough ML, Feskanich D, Stampfer MJ, et
al. Adherence to the Dietary Guidelines for Americans and risk
of major chronic disease in women. Am J Clin Nutr. 2000;72:1214-1222.
Hu FB, Rimm EB, Stampfer MJ et al. Prospective
study of major dietary patterns and risk of coronary heart disease
in men. Am. J. Clin Nutr. 2000;72:912-921.
Key Messages
- According to the NHS, adhering to the Dietary Guidelines for
Americans lowered CVD risk by 14% in women. It did not reduce
their risk of cancer or other chronic diseases.
- Multivariate RR for CVD, cancer, and nontraumatic deaths were
0.86, 1.02, and 0.97 for women in the highest HEI group
- HEI need to be refined to better determine optimal diet.
- Healthy eating pattern was associated with low CHD risk in
Health Professionals Follow-up Study.
- The prudent pattern, diets high in fruits, vegetables, fish,
and poultry was inversely associated with CHD risk, while the
Western pattern, diets high in fat, red meats, processed meats,
refined grains, and French-fries were directly associated with
CHD risk.
Table of Contents
Lutein and zeaxanthin, 2 carotenoids commonly
found in egg yolks, corn age-related macular degeneration by preventing
, spinach, and other green leafy vegetables, have been shown to
protect against age-related macular degeneration by preventing
light-initiated oxidative damage from occurring in the retina.
Earlier studies showed that diets high in lutein and zeaxanthin
increase the concentration of these 2 carotenoids in the macular
region of the retina. But the results from Johnson et al. indicated
that diets high in these carotenoids could also increase concentrations
of these nutrients in other parts of the body.
In this 2-pronged study, the researchers first
evaluated the changes in lutein and zeaxanthin concentrations at
various tissues following a diet supplemented with 60 grams of
spinach and 150 grams of corn per day. Lutein and zeaxanthin concentrations
in serum, adipose tissue, and buccal mucosa cells (BMC) were measured
at baseline and weeks 4, 8, 12, and 15 of supplements, as well
as 2 months post study. The macular pigment density and dietary
carotenoid intakes were also measured throughout the study period.
Seven healthy middle-aged adults (4 women and 3 men) participated
in this section of the study.
After 4 weeks of corn and spinach intake,
serum lutein concentrations nearly doubled from baseline and continued
to remain elevated during the feeding period. However, eating corn
and spinach had a less dramatic effect on serum zeaxanthin levels.
For example, zeaxanthin levels increased from 58±12 nmol/l at baseline
to 74±14 nmol/l at week 4. On the other hand, 2 months after the
cohort stopped adding corn and spinach to their diets, both serum
lutein and zeaxanthin concentration returned to baseline level.
Besides raising serum carotenoid levels, corn and spinach intake
also raised lutein concentration in BMC. In contrast, BMC zeaxanthin
levels were unchanged throughout the study. The mean beta-carotenoid
levels did not change in any tissue.
Unlike the concentrations of lutein and zeaxanthin
in serum, BMC, and adipose tissue, the lutein and zeaxanthin concentrations
in retina as indicated by macular pigment (MP) density continued
to be elevated even after subjects discontinued eating corn and
spinach daily. Also, the researchers observed an inverse pattern
for zeaxanthin and lutein levels between MP density and adipose
tissue. For examples, lutein and zeaxanthin concentrations in adipose
tissue initially decreased at week 4, but rebounded after 8 weeks
on the diet. MP density increased at week 4 and began leveling
off thereafter. This observation lead the researchers to suggest
that these 2 sites might compete for carotenoids from serum. The
mean beta-carotenoid levels did not change in any tissue.
In the second part of this study, using 21
study subjects (13 women and 8 men), the researchers evaluated
the cross-sectional relations among anthropometric measurements,
MP density, serum, adipose tissue, and dietary lutein to further
test possible interactions among tissues. The data clearly showed
that there was a competition for lutein among different tissues.
For example, percent body fat was inversely related to lutein concentrations
in BMC, meaning that in people with higher % body fat, less lutein
would be available for other uses. Data also indicated that there
is a difference in carotenoid metabolism between the sexes. Even
with significantly lower carotenoid intakes, women had similar
serum carotenoid levels as men, and a higher lutein concentration
in adipose tissue.
From these results, Johnson et al. concluded that "lutein
and zeaxanthin are dynamic components of tissues and that the metabolism
of lutein maybe different between women and men." However, due
to the small cohort size and menopausal status of the females in
the study, 9 out of 13 women were postmenopausal and not on HRT,
it is difficult to determine if the observations are due to a gender
difference or hormonal status.
Johnson EJ, Hammond BR, Yeum KJ, et al. Relation
among serum and tissue concentrations of lutein and zeaxanthin
and macular pigment density. Am J Clin Nutr. 2000;71:1555-1562.
Table of Contents
Previous studies have reported an inverse
relationship between whole grain consumption and CVD. And now 2
studies by Liu et al. show a similar association between whole
grain intake and risk of ischemic stroke and type 2 diabetes in
women. Data for both studies were based on the 12 year Nurses'
Health Study in a cohort of 75,521 women.
Mortality from stroke is more common in women
than men. In light of the limited data on this topic, the findings
by Liu et al. are especially valuable to lower stroke risk. The
median whole grain intake ranged from 0.13 serving/day in the lowest
quintile to 2.70 serving/day in the highest quintile. Women with
a higher whole grain intake ate healthier (diet low in fat and
alcohol and higher in folate, fruits and vegetables, and carbohydrates)
and practiced healthier lifestyles (exercised regularly, took supplements,
hormone replacements).
There were 352 confirmed cases of ischemic
stroke during follow-up and was less common among the groups with
higher whole grain intakes. The age adjusted RRs of ischemic stroke
were 0.68 (second quintile), 0.69 (third quintile), 0.49 (fourth
quintile), and 0.57 (fifth quintile). The RRs were attenuated when
other CVD risk factors were included in the analysis. The multivariate
RR was 0.69 in the fifth quartile for whole grain. However, refine
grains and total grains (refined plus whole grains) had no significant
effect on ischemic stroke. The multivariate RRs were 0.97 and 0.79
in the highest refine and total grain intake groups, respectively.
Of all the CVD risk factors, smoking was the strongest compared
to dietary factors such as saturated fat or trans-fatty acids,
and fruit and vegetable intake. Earlier studies have shown that
different compounds found in whole grains, such as folate, vitamin
E, and fiber, may explain some of the protective effects of whole
grain, however, since the primary objective of this study was to
evaluate the overall impact of whole grain intake on ischemic stoke,
the researchers did not adjust for these in the analysis.
Results from the Nurses' Health Study also
suggest that whole grain intake is inversely associated with type
2 diabetes while refined grains raise the risk of diabetes mellitus.
Based on this food-based analysis, the data showed that compared
to women in the lowest quintile for whole grain intake, women in
the highest quintile had a 38% lower risk of developing diabetes.
This relationship was slightly attenuated when BMI, cigarette smoking,
alcohol intake, family history of diabetes, and use of multivitamins
and supplements were included in the analysis. The age and energy
adjusted RR for the highest quintile of refined grain intake was
1.31. On the other hand, total grain intake was not significantly
associated with diabetes risk.
When the researchers compared the relationship
between the ratio of refined to whole grain to diabetes risk, they
found that women in the highest refined grain intake and lowest
whole grain intake had a 57% greater risk of type 2 diabetes. In multivariate
analysis, the RR was reduced to 1.26. Surprisingly, including saturated
fat and trans-fat in the analysis did not alter the RR. Also, of
the 1879 reported cases of type 2 diabetes during the 10-year follow-up,
1475 cases occurred in women with BMI values greater than 25. Separate
analysis of grain intake and diabetes risk in this subgroup showed
similar outcomes. The multivariate-adjusted RR across ascending
quintiles were 1.00, 1.07, 1.14, 1.25, and 1.33 compared to 1.00,
1.09, 1.17, 1.27, and 1.25 in the full cohort, thus indicating
that high whole grain and low refined grain is beneficial regardless
of weight.
The results of these studies suggest that
not all grain products are alike. Whole grain products, which tend
to be absorbed more slowly as well as eliciting smaller post prandial
glucose responses, lower type 2 diabetes risk, while refined grain
intake increases risk. Clearly, it is important to distinguish
these grains when counseling patients. In light of the fact that
on average consumers eat less than one serving of whole grain products
in an average 2000 kcal diet, there is a clear need to educate
consumers to replace refined grain products with whole grain foods
to lower the risk of diabetes and other chronic diseases.
Results from these studies show that high
consumption of whole grain foods lowers the risk of ischemic stroke
and type 2 diabetes in healthy middle-aged women, independent of
other traditional CVD risk factors. And since the current average
intake of whole grain is less than the recommended 3 serving per
day, there is considerable room for promotional and educational
efforts to encourage consumers to increase their whole grain intake.
Liu S, Manson JE, Stampfer MJ, et al. A prospective
study of whole-grain intake and risk of type 2 diabetes mellitus
in US women. Am J Public Health. 2000;90:1409-1415.
Liu S, Manson JE, Stampfer MJ, et al. Whole
grain consumption and risk of ischemic stroke in women. JAMA.
2000;284:1534-1540.
Table
of Contents
To the ever-growing list of emerging CHD risk
factors, we might be able to add lipoprotein-associated phospholipase
A2, "a family of enzymes that can hydrolyze phospholipids at the
sn2 position to generated lysophospholipids and fatty acids." Lipoprotein-associated
phospholipase A2 is also known as platelet-activating factor acetylhydrolase.
And according to Packard et al., elevated levels of lipoprotein-associated
phospholipase A2, which is regulated by mediators of inflammation,
appear to be a strong risk factor for CHD. Packard et al. also
showed that C-reactive protein, white-cell count, and fibrinogen
are good predictors of CHD risk.
Using baseline measures of C-reactive protein,
white-cell count, fibrinogen, and lipoprotein-associated phospholipase
A2 in a subgroup of men in the West Scotland Coronary Prevention
Study, Packard and colleagues tested the relationship between chronic
inflammation and CHD events. A total of 580 men with reported cases
of study outcomes; nonfatal myocardial infarction, death from CHD,
or a revascularization procedure, and 1160 healthy men were enrolled
in this study. The control group was matched for age and smoking
pattern.
To no surprise, analysis of the data showed
that the subjects who suffered a coronary event had many more CHD
risk factors than the control group. Also, the plasma levels of
4 inflammation markers were higher in the case group. Univariate
analysis showed that plasma fibrinogen concentrations, white-cell
count, C-reactive protein levels, and lipoprotein-associated phospholipase
A2 were associated with 19%, 22%, 27%, and 20% increases in study
outcome. However, compared to the C-reactive protein, which is
highly interdependent with white-cell count, fibrinogen, and other
CHD risk factors, the lipoprotein-associated phospholipase A2 showed
weak or no relationship with fibrinogen and white-cell count, respectively.
And only the plasma LDL-cholesterol level was associated with lipoprotein-associated
phospholipase A2. Smoking was associated with increased C-reactive
protein, fibrinogen, and white-cell counts, but there was no association
with the lipoprotein-associated phospholipase A2.
Data from this study also confirmed an earlier
meta-analysis finding that compared to subjects in the lowest quintile
for C-reactive protein, white-cell count, and fibrinogen, those
in the highest quintile had RR of 2.0 for CHD. However, when other
inflammation markers and CHD risk factors were included in the
analysis, the risk ratio dropped to 1.49 in the highest quintile
for C-reactive protein. But in the case of lipoprotein-associated
phospholipase A2, other inflammation markers and CHD risk factors
had little effect on lowering the RR.
In conclusion, results from the study by Packard
et al. confirm earlier findings showing that chronic inflammation
does increase CHD risk in hypercholesterolemic men. But, it goes
one step further to suggest that lipoprotein-associated phospholipase
A2 is a better predictor of CHD risk than C-reactive protein, white-cell
count, and fibrinogen, since unlike these 3 other inflammation
markers, it's effects are independent of other inflammatory marker
or other CHD risk factors.
Packard CJ, O'Reilly DS, Caslake MJ, et al. Lipoprotein-associated
phospholipase A2 as an independent predictor of coronary heart
disease. N Engl J Med. 2000;343:1148-1155.
Table of Contents
As you all know, the prevalence of obesity
is increasing worldwide. And the a major culprit behind this
problem. However, shealth community has blamed widespread acceptance
of a high-fat Western diet as a major culprit behind this problem.
However, since the incidence of obesity is high among undernourished
populations in China, Brazil, and South Africa, the current theory
of excess food calories and lack of physical activity causing obesity
does not apply to all. Therefore, using Hubel and Wiesel's theory
of a critical period in which early-life stimuli may permanently
affect metabolic development, Hoffman et al. tested the hypothesis
that nutritional stunting is associated with impaired fat oxidation
in poor Brazilian children.
By comparing fasting and post-prandial energy
expenditure, respiratory quotients (RQ), and substrate oxidation
in 28 stunted children and 30 normal height children, the researchers
were able to show that the fasting RQ was significantly higher
in the stunted group (0.92±0.009) vs. the control group (0.89±0.007).
Also, the rate of fasting fat oxidation was lower in the stunted
group (25±2% vs. 34%±2%). The lean body mass adjusted resting energy
expenditures and post-prandial thermogenesis values were not significantly
different between the 2 study groups. This metabolic feeding study
lasted 3 days. Parents of both study groups had similar BMI and
stature.
As with other at risk populations for impaired
fat oxidations such as Pima Indians, stunted children were more
likely to have problems oxidizing fat and, as a result, store more
fat in their adipose tissues. Due to the nature of the study design,
the study was unable to identify whether deficiencies of certain
nutrients or malnutrition in general were responsible for the impaired
fat oxidation in the stunted group. The mechanisms behind this
relation are unclear, but the researchers speculated that long-term
undernutrition might have damaged enzymes and hormones responsible
for optimal lipid oxidation. Finally, Hoffman et al. concluded
that even though this study was conducted in a different country,
undernutrition occurs in our backyard and needs to be monitored
in order to prevent unnecessary weight problems in children and
eventually in adults.
Hoffman DJ, Sawaya AL, Verreschi I, et al.
Why are nutritionally stunted children at increased risk of obesity?
Studies of metabolic rate and fat oxidation in shantytown children
from San Paulo, Brazil. Am J Clin Nutr. 2000;72:702-707.
Table of Contents
Health promoting programs have long supported
a prudent diet, low in fat and cholesterol and high in fruits,
vegetables, and grain products for adults and children over 2 years
old, to reduce their CHD risk and atherosclerosis development.
However, the same group of health professionals stress caution
when it comes to the diets of infants and toddlers less than 2
years old. But according to the result from the Special Turku Coronary
Risk Factor Intervention Project (STRIP) in Finland, an early intervention
diet, low in SFA and cholesterol, was effective in keeping serum
total cholesterol and LDL cholesterol levels lower in young boys.
However, there was no significant difference noted with girls.
Compared to the control group (n=522), which
received routine health education during the well-baby check-up,
parents of children in the intervention group were given specific
diet instructions to offer daily cholesterol of <200 mg/day
and 30-35% of total energy as fat with a PUFA, MUFA, SFA ratio
of 1:1:1. Diet records and serum cholesterol levels were collected
regularly to assess compliance.
Throughout the intervention period, 7 months
to 60 months, the intervention boys had 6 to 10% lower mean serum
cholesterol levels than the control boys. The serum non-HDL and
apo B concentrations were 6-11% and 4-7%, respectively, lower than
the control group. The male control group, on the other hand, had
slightly higher HDL cholesterol levels and apo A-I concentrations
than the male intervention group, however, the overall total cholesterol:HDL
ratios were not significantly different. And from the only fasting
blood sample at age 5, the mean LDL cholesterol was 9% lower in
the intervention boys. Differences in serum cholesterol, non-HDL,
apo B, LDL, TAG, and total cholesterol:HDL ratio were not significant
between 2 female groups.
Growth analysis between control and intervention
kids showed no differences in height, weight, and BMI indicating
that following a low-SFA and cholesterol diet was not detrimental
to their physical development.
In conclusion, these data indicate that diets
which contribute 30-35% of calories as fat with equal parts MUFA,
PUFA, and SFA are effective in controlling blood lipids and lipoprotein
levels in young boys without negatively affecting their physical
development. But the benefits of such a diet were not shown in
young girls.
Rask-Nissila L, Jokinen E, Ronnemaa T, et
al. Prospective, randomized, infancy-onset trial of the effects
of a low-saturated-fat, low-cholesterol diet on serum lipid and
lipoproteins before school age. The special Turku coronary risk
factor intervention project (STRIP). Circulation. 2000;
102:1477-1483.
Table of Contents
Thanks to many important vitamins and phytochemicals
found in orange juice (OJ), it has long been considered one of
the healthiest beverages. And now a report from Kurowski et al.
shows that drinking 3 cups of OJ can protect the heart by raising
HDL cholesterol levels. It is thought that hesperetin, a citrus
flavonoid found in the orange, is responsible for improving plasma
lipoprotein levels.
In this 12-week feeding study, 25 healthy
adults (16 men and 9 postmenopausal women) with total blood cholesterol
levels of 170 mg/dl to 325 mg/dl included 1, 2, and 3 cups of OJ
in their AHA step 1 diet. Each test period lasted 4 weeks, followed
by 5 weeks of an orange free diet. Plasma lipid and lipoprotein
levels were measured throughout the study. As expected, the dietary
records indicated that vitamin C and folate intakes were significantly
higher during the highest OJ consumption period. Also,
total energy and grams of CHO intake increased incrementally with
each cup of OJ.
Analysis of overall changes in lipid and lipoprotein
profiles showed that plasma HDL and TAG levels increased by 21%
and 30%, respectively, following the 3 cups of OJ period. The LDL-HDL
ratio decreased by 16% since LDL cholesterol levels were unchanged.
In addition to altering blood lipids, drinking OJ was associated
with raising plasma vitamin C and folate levels by 3.8 folds and
18%, respectively, with 3 cups/day of OJ consumption. However,
in spite of the significant increase in folate levels during all
3 diet periods, plasma homocysteine levels were unchanged throughout
different dietary periods.
Compared to baseline levels, plasma HDL cholesterol,
vitamin C, and folate levels remained elevated even after the subjects
stopped drinking OJ. But only the HDL cholesterol level was higher
during the washout period than the highest OJ period. The changes
in HDL cholesterol concentrations with OJ consumption were inversely
related to the baseline HDL indicating that people with low baseline
HDL cholesterol saw higher increases in their HDL cholesterol levels
than people with higher baseline HDL levels.
In conclusion, the study by Kurowska et al.
suggests that drinking OJ is an easy way for adults to improve
their plasma HDL cholesterol and folate levels. This cardioprotective
benefit continued even after 5 weeks of not drinking OJ. But the
researchers encouraged everyone to obtain a variety of nutrients
by eating at least 5 serving of fruits and vegetables daily rather
than simply loading up on OJ.
Kurowska EM, Spence JD, Jordan J, et al. HDL-cholesterol-raising
effect of orange juice in subjects with hypercholesterolemia. Am
J Clin Nutr. 2000;72:1095-1100.
Table of Contents
The American Heart Association Dietary Guidelines
2000 represent a giant step forward in transforming nutritional
recommendations from a consumer-confusing quantitative game of
percentages to a much friendlier qualitatively concept which individuals
can actually apply in heart disease prevention. Finally, after
years of fat, salt and cholesterol phobia, there is less emphasis
on the numbers and more emphasis on dietary patterns; less obsession
on whether one hits the targets daily (for some it was each meal,
for others each item) replaced with patterns over days or weeks;
and, most importantly, a softening of the "one diet fits all" approach
in favor of the recognition that human beings are not physiologically
an inbred genetic strain. The AHA Nutrition Committee has demonstrated
both rationale thought and practical considerations into these
guidelines and, unlike many diet gurus with their fixated dogmas,
recognizes and admits that there are uncertainties and vagaries
within the recommendations. They have left room for the fact that
nutrition is a dynamic science which will change over time and
will necessitate flexibility in a dynamic population with changing
environments and lifestyles.
In the 70s when dietary recommendations were
being debated at congressional hearings, a number of nutritionists
and public health advocates were concerned about the negative messages
in the guidelines, that the food industry and public might misinterpret
the objectives and move in the wrong direction, and that the recommended
changes might be excessive given the paucity of hard evidence.
Through the next thirty years we had the "bad cholesterol" phase,
the "bad fats" phase and now the "bad saturated fats" phase. And
after a quarter century of avoidance, substitution and replacement,
we now move from the old paradigm emphasis on removing the negative
ingredients (e.g. cholesterol, fat and salt) to a new paradigm
emphasis on values and benefits of positive ingredients (e.g. antioxidants,
vitamins, minerals, fiber and phytochemicals). Rather than the
message "don't eat fatty meats, whole dairy products and eggs" the
public now hears "include fish in the diet, 5 servings of fruits
and vegetables, 6 or more servings of whole grains and legumes,
low-fat dairy products, lean meats and poultry." The AHA guidelines
emphasize foods and an overall healthy eating pattern, and the
need to achieve and maintain a healthy body weight through avoidance
of excess total energy intake and a regular pattern of exercise.
The concept that "most people will be able to focus on the positive
message of selecting healthy foods, rather than trying to follow
a diet based on percentages" should return daily meals to an enjoyable
experience rather than a 'life and death' decision.
Dietary restrictions focus on "the major components
that raise LDL cholesterol . saturated fats, trans-fat, and to
a lesser extent, dietary cholesterol." The guidelines state "Although
there is no precise basis for selecting a target level for dietary
cholesterol intake for all individuals, the AHA recommends <300
mg/d on average. By limiting cholesterol intake from foods with
a high content of animal fats, individuals can also meet the dietary
guidelines for saturated fat intake. This target can be readily
achieved, even with periodic consumption of eggs and shellfish." Finally
there is a recognized disassociation of saturated fat from cholesterol,
and foods low in saturated fat, like eggs and shellfish, are not
tarred with the same "saturated fat and cholesterol" brush. AHA
noted that a major change from the old "recommended that individuals
eat no more than 3 egg yolks per week" was replaced with "The recommended
intake of dietary cholesterol remains the same - however, individuals
may choose to eat one egg yolk daily, if the amount of foods high
in dietary cholesterol in the rest of their diet is very limited." An
egg a day really is okay!
But now the real task begins. How do we educate
a population which for the most part has only heard the "don't
eat this, don't eat that" nutrition messages? How do we turn around
the fat and cholesterol phobias into broad based acceptance of
eating patterns, weekly averages, and those old fashioned concepts
of balance, variety and moderation? We moved the national diet
from high-fat, calorie-rich, nutrient-poor to one of low-fat, high-carbohydrate,
calorie-richer, nutrient-poor and now must again shift the pattern
even more dramatically to one of moderate-fat, calorie-moderate,
nutrient-dense, with a healthy dose of physical activity. And you
thought the last quarter century of changes and education were
hard work!
Donald J. McNamara, Ph.D.
Executive Editor, Nutrition Close-Up
Table of Contents
 Executive
Editor: Donald J. McNamara, Ph.D.
Writer/Editor: Linda Min, M.S., R.D.
Nutrition Close-Up is published quarterly
by the Egg Nutrition Center. Nutrition Close-Up presents
up-to-date reviews, summaries and commentaries on the latest research
investigating the role of nutrition in health promotion and disease
prevention, and the contributions of eggs to a nutritious and healthful
diet. Nutrition and health care professionals can receive a FREE
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