| Volume 15 – Number 4 | Winter 1998 |
TABLE OF CONTENTS
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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
Adiposity Levels Increase Lipid and Lipoprotein Levels
Thanks to many studies, the association between excess body weight and CHD risk has been established and obesity is recognized as an independent risk factor for CHD. In addition, a new study by Siervoges et al. indicates that annual changes in ones’ adiposity is correlated with corresponding annual changes in plasma lipid and lipoprotein levels. In this longitudinal study, researchers analyzed data from 1,304 serial examinations in 423 Caucasian adults (221 women and 202 men) involved in the Fels Longitudinal Study. The data used in this study were collected since 1976 with a follow-up examination scheduled every 5 years for adults between 25-40 years old and every 2 years for all other age groups. The data reported in this report were separately analyzed based on sex and on age, 18-44 year old group versus 45-65 year old group. All participants had at least 2 examinations within the specified age group with a minimum of 4 years between examinations. In the cases with greater than 2 examinations, all data were used in the analysis. Under-water weighting (hydrodensitometry) was used to measure body density and total body fat (TBF); percent body fat (%BF) and fat free mass (FFM) were calculated.
There were distinct gender and age difference in body composition and concurrent changes in plasma lipid and lipoprotein levels in the study participants. For example, females had higher levels of TBF, %BF, and HDL cholesterol levels while males had higher levels of FFM, total cholesterol, LDL cholesterol, and TAG levels. BMI values were similar for younger males and younger females at 23.7; however, older males and females had higher TBF, %BF, BMI, total cholesterol, LDL cholesterol, and TAG levels than younger adults. Plasma HDL cholesterol levels increased in older females only. Also, the rates of annual changes in adiposity and plasma lipid and lipoprotein levels were different among the various age-gender groups. The younger male group had the largest annual change in body composition and lipid parameters followed by older females, young females, and finally, older males. All variables, except HDL cholesterol levels, increased annually in younger males, while only BMI, TBF, %BF, and TAG levels changed in younger females. In older men, plasma total cholesterol and LDL cholesterol exhibited a decrease, but the TAG annual change was positive in older women. The rate of increase in BMI was greater in young males (0.20 kg/m2 per year) than older males (0.12 kg/m2 ) where as younger and older females had similar rates of change in BMI values (0.16 and 0.18 kg/m2 per year, respectively). These increases in BMI were associated with changes in plasma total, LDL, and HDL cholesterol levels. The data indicate that lipid and lipoprotein levels in males in the younger age group were more sensitive to body fat gain. The changes in HDL cholesterol levels were negatively associated with adiposity measures. The FFM did not affect plasma lipid and lipoprotein levels as seen with adiposity levels. Results from this study indicate that the greater increase in adiposity in younger males, and continued fat gain in women with age, in part can account for the observation of previous cross-sectional studies which showed that plasma lipoprotein levels increase linearly until age 45 in both sexes, but plateaus out in males while continuing to increase in older women. The association between lipid and lipoprotein levels with adiposity level was across the entire body weight range and not just for overweight individuals.
This study was the first to examine the long-term effects of changes in body composition and lipoprotein levels in non cardiac or overweight subjects. It showed that in healthy adults with no cardiovascular disease, changes in ones’ body fat can affect plasma lipid and lipoprotein parameters. The males in the 18-44 age group gained the most total body fat per year and accordingly their total cholesterol, LDL cholesterol, and TAG levels increased the most. The total cholesterol, LDL, and TAG levels plateaued in the older male group, which coincided with a slower fat gain. In women, age was not a factor, both lipoprotein and body fatness increased with age. Therefore, Siervogel et al. concluded that between “4-25% of the variation in the annual rate of increase in specific lipid and lipoprotein level” is attributed to change in adiposity. Also, they stated that “the findings clearly demonstrate that consistent increases in adiposity in individuals are associated with changes in lipid and lipoprotein levels in the direction of increased risk for cardiovascular disease.”
KEY Messages
- Rate of body fat gain is associated with lipid and lipoprotein levels.
- Lipid and lipoprotein levels in 18-44 year old males are the most sensitive to change in adiposity levels.
- Lipid and lipoprotein levels increase linearly until the age of 45 than leveled off in older males, but continued to increase in older females.
Siervogel, R.M., Wisemandle, W., Maynard, L.,M., et al. Serial changes in body composition through out adulthood and their relationships to changes in lipid and lipoprotein levels. The Fels Longitudinal Study. Arterioscler Thromb Vasc Biol 1998;18:1759-1764.
Fat and Cholesterol Intakes Have Little Effect on Plasma Lipoprotein Levels in Mennonites
The old adage that “you are what you eat” may not hold true in an old order Mennonites community in Yates County, New York. In a study with 223 Mennonites, researchers observed that high total fat, saturated fat, and cholesterol intakes were not associated with adverse plasma lipoprotein profiles in Mennonite men and women. The average serum cholesterol levels of Mennonite women (193 mg/dl) were much higher than in Mennonite men (178 mg/dl). Analysis of the National Cancer Institute’s 60-item food frequency questionnaire completed by participants indicated that the total nutrients consumed were much higher, the percentage of major nutrients was similar between Mennonites and the US sample population; calories of fat between 39-41%, calories from protein between 15-16%, and calories from CHO between 42-46%. Also, systolic and diastolic blood pressure levels of Mennonite men were 122 mm/Hg and 75 mm/Hg, respectively, and the Mennonite women’s were 113 mm/Hg and 70 mm/Hg, respectively. When this information was compared with the 1987 National Health Intervention Survey results, Mennonite men had lower cardiovascular risks than non-Mennonite men. However, female Mennonites had several similar cardiovascular risk factors as females in the National survey. Lastly, the Mennonites were slight thinner than the general population with BMI levels of 25 versus 26 for the US population.
Glick et al. hypothesized that Mennonite men reaped cardiovascular protection from their rigorous physical life-style associated with limited automation on their farms. The gender difference in serum cholesterol levels found in this study were thought to be the result of multiple gestation that is associated with elevated plasma cholesterol and physiological difference in cholesterol metabolisms.
Even though their findings are interesting, there are several limitations associated with this study. For example, anthropometric measures were self-reported, there are a number of differences in methodologies as well as in time frame between the current study and the national survey, and there was a one year lag time between blood draw and completion of food frequency questionnaires. However, the data are consistent with other reports that an agrarian diet with high intake of total fat, saturated fat, and cholesterol is not related to hypercholesterolemic in the presence of strenuous physical activity and low adiposity.
Glick, M.G., Michel, A.C., Dorn, J.et al. Dietary cardiovascular risk factors and serum cholesterol in an old order Mennonite community. Am J Public Health 1998;88:1202-1205.
High Lutein and Zeaxanthin Found in Egg Yolks
As the number of elderly increases, more and more research is being conducted on older adults. These studies are trying to understand, delay, and possibly prevent chronic diseases such as heart disease, Alzheimer, and age-related macular degeneration (ARMD) which commonly afflict the elderly. Two carotenoids, lutein and zeaxanthin, have recently received attention for their potential role in delaying ARMD. The increased interest in these carotenoids stems from studies showing a direct association between carotenoid intake, plasma concentrations and macular pigment density. In addition, carotenoids act as antioxidants to protect the retina from photo toxic damage. Sommerburg et al. measured the lutein and zeaxanthin content in 33 fruits and vegetables, 2 fruit juices, and egg yolk. Egg yolk and maize (corn) contained the highest concentrations of lutein and zeaxanthin, much more than green leafy vegetables, which are commonly recommended to provide a high carotenoid intake. Fruits and vegetables of different color had highly variable content of zeaxanthin and lutein.
From their findings, Sommerburg et al. concluded that the best way to increase the dietary intake of lutein and zeaxanthin is by eating a variety of fruits and vegetables of various colors, as well as adding eggs to ones’ diet. They stated that “the consumption of eggs could actually be beneficial to obtain a higher intake of lutein and zeaxanthin, and since it has no severe adverse effects on cardiac risk factors, the exclusion of eggs from the diet could be reconsidered.” The current recommendation advocated by Sommerburg et al. to increase lutein and zeaxanthin levels in elderly are certainly in-line with the USDA’s recommended eating pattern seen in the Food Guide Pyramid.
Sommerburg, O., Keunen, J.E., Bird, A.C., et al. Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes. Br J Ophthalmol 1998;82:907-910.
Adding An Egg A Day Increased Plasma HDL Cholesterol Levels
During the 80s, dietary cholesterol was one of the dietary evils when it came to heart disease. And since eggs are a concentrated source of dietary cholesterol, they became the icon for both dietary and blood cholesterol and were banned from many breakfast plates. This occurred in spite of the lack of scientific evidence to support a relationship between egg intake and blood cholesterol levels. Since those days, opinions about eggs and dietary cholesterol have slowly changed and more studies have been published that question the recommendation to limit egg consumption. Results from a new study by Farrell support this concept. In healthy men and women, adding 1 egg/day to their diet, their lipoprotein profile was not altered, and only the TAG level was slightly increased with 1.5 eggs/day diet. Some of the eggs consumed in this study were enriched with n-3 long-chain fatty acids. However, results on lipoprotein levels were similar regardless of the different type of eggs consumed.
In this study, 56 subjects were randomly assigned to one of the 4 egg groups for 24 weeks. The eggs were obtained from hens fed 4 test diets; diet F contained 50 gm fish oil/kg; the FL diet contained 30 gm fish oil/kg and 10 gm linseed oil/kg; FLR diet contained 20 gm fish oil/kg, 10 gm linseed oil/kg, and 10 gm/kg canola oil/kg, and the control diet contained 40 gm sunflower oil/kg. The study subjects’ baseline diets averaged 34% of calories from fat with 15% from SFA, 12% from MUFA, and 7% from PUFA [Unfortunately, the author did not provide data from baseline dietary cholesterol intakes.]
During the first 22 weeks, when subjects added 7 eggs/week to their diets, HDL cholesterol levels increased from 32 mg/dl to 42 mg/dl. LDL cholesterol levels decreased from 151 mg/dl to 139 mg/dl. However, when the egg intake was increased to 21 eggs/wk for the last 2 weeks, plasma cholesterol and lipoprotein cholesterol levels were unchanged. There were no differences in plasma lipoprotein levels or blood pressures between different egg types. Farrell also conducted sensory evaluations and shelf-life measures of enriched eggs vs regular eggs. The results showed that people could not identify the enriched egg from regular eggs and they were equally accepted. The shelf-life of the various eggs was similar.
In conclusion, this study shows that both ordinary eggs and omega-3 enriched eggs can be added to ones’ diet without adversely affecting lipoprotein levels and, as found in other studies, can actually increase plasma HDL levels.
Farrel, D.J. Enrichment of hen eggs with n-3 long-chain fatty acids and evaluation of enriched eggs in humans. Am J Clin Nutr 1998;68:538-544.
Clinical Depression and CHD In Men
In recent years, several new risk factors have been added to the common CHD risk factors. In addition to hyperhomocysteinemia, certain types of infections, and Lp(a), there is now evidence that clinical depression should be added to this growing list. In a prospective study, Ford et al. observed an increased incidence of CHD in male doctors with clinical depression compared to their control counterparts. One thousand one hundred ninety healthy male subjects, without history of clinical depression, attending the Johns Hopkins Medical School between 1948 and 1964 were enrolled for this study. Baseline information regarding health behavior, health status, and family history of CHD, were initially collected and new information added through annual questionnaires. One hundred twenty-three men reported an episode of clinical depression during the 37 year median follow-up period. The baseline characteristic differences between the 2 groups were quite minor. For example, men who developed clinical depression were older by one year at the time of graduation (27 vs 26 yr) and drank more coffee (3 vs 2 cups) at baseline than the control group. But traditional CHD risk factors and health behaviors were similar in both groups. However, males that became clinically depressed were twice as likely to develop CHD. The relative risk of CHD among clinically depressed subjects who did not smoke or drink was 1.8 and the RR was 1.8 for depressed men who did smoke and 2.0 for depressed men who drank. The RR for CHD was slightly lowered (1.7) when other CHD risk factors were considered in the analysis. There data indicate that smoking and alcohol were not contributory factors to the increased risk but rather that clinical depression is an independent risk factor for CHD. Also, using multivariate analysis, the authors found that clinical depression was more strongly associated specifically with incidence of CHD and MI (RR= 2.12) than with total CVD incidence (R =1.52) or cerebrovascular accidents (RR= 0.93).
In addition to an increased mortality from suicide, CVD mortality was associated with clinical depression with a RR of 1.8. Clinical depression was an independent risk factor for CHD (RR = 2.1) even after 10 years from onset of depression indicating that pre-existing CHD was not a confounding variable. Lastly, Ford et al. considered the possibility that tricyclic agents used by depressed subjects increased CHD risk due to cardiac effects. The data showed that RR for clinical depression was higher for subjects being treated with psychotherapy with or without sedative (RR=2.33) compared to those treated with antidepressant medication (RR=1.89) which was higher than subjects not being treated (RR=0.94).
The mechanism involved in the association between increased CHD and depression is not known, but researchers speculated that it might be attributed to “altered autonomic tone as manifested by less heart rate variability,” sympathetic nervous system effects, increased platelet reactivity, or behavior changes that prompt patients not to seek medical care. Research this area is far from conclusive, but does seem to show that depression not only decreases survival rates following MI but also can contribute to CHD risk.
Ford, D.E., Mead, L.A., Chang, P.P., et al. Depression is a risk factor for coronary artery disease in men. The precursors study. Arch Intern Med 1998;158:1422-1426.
Very Low Saturated Fat Intake Decreases CHD Incidence in Indians
Contrary to the findings seen in Mennonite men by Glick et al., a similar study in subjects living in India arrived at different conclusions. In this population, Singh et al. observed a direct association between saturated fat intake and prevalence of CAD. Using a 7-day dietary intake record, researchers determined the association between saturated fat intake and CAD in 1,806 (904 men and 902 women) adults from Moradabad in north India. In addition, complete baseline information regarding the subjects’ other CHD risk factors, socioeconomic status, and education level were measured.
According to the data, people with skilled occupations, more education, and higher income levels were likely to fall into the high saturated fat (>10% of kcal/day) and low saturated fat (7-10% kcal/day) groups, while poor unskilled laborers ate very low amounts of saturated fat (<7% kcal/day). Also, older males (n=100) were more likely to have suffered from CAD than females (n=63). Saturated fat intake was directly associated with CAD incidence in both sexes. For example, the prevalence of CAD in males and females were 4.7% and 3.3% in the very low saturated fat group, 10.6% and 6.2% in the low saturated fat group, and 18.5% and 12.2% in the high saturated fat group. Saturated fat intake was also associated with other major risk factors for CAD in both men and women. Total cholesterol, BMI, and blood pressure decreased with very low saturated fat intakes, but the difference in TAG and HDL and LDL cholesterol levels among different levels of saturated fat intakes were not significant. However, multivariated analyze abated the association of levels of saturated fat intakes with the prevalence of CAD, with odds ratios of 0.93 in men and 0.76 in women, suggesting that the overall life-style pattern was a stronger determinant of risk than simple saturated fat intake.
In conclusion, this study showed that in developing countries, the recommendation of less than 30% calories from fat and less than 10% of calories from saturated fat might not be as effective in controlling CAD as seen in developed countries. Especially since the mean population plasma cholesterol levels are already at the desirable levels of less than 200 mg/dl. The authors recommended that in this population, saturated fat intakes be less than 7% of calories to protect one from CHD risk and other CHD risk factors; however, unless the other risk factors (elevated serum cholesterol, hypertension, physical inactivity, excess weight and smoking) are addressed these dietary restriction may have little benefit.
Singh, R.B., Niaz, M.A., Ghosh, S., et al. Low fat intake and coronary artery disease in a population with high prevalence of coronary artery disease: The Indian paradox. J Am Coll Nutr 1998;17:342-350.
The 1998 American Heart Association Annual Meeting Abstract Reviews
The following briefs cover some of the many abstracts presented at the 71th Scientific Sessions of the American Heart Association (AHA) held in Dallas, Texas this past November. Abstracts are published in Circulation, AHA’s bimonthly journal.
Genetic predictors of favorable and adverse lipid responses to lower fat diets in men. Studies determined the contributions of various genetic factors to the variability of LDL:HDL ratio responses to low-fat diets in men. Data indicate that lowering total and saturated dietary fat can have adverse, neutral or positive effects on the ratio of LDL to HDL and overall risk assessments. These investigators examined the effects of 14 genetic variants of 7 genes on the LDL:HDL response to changes in dietary fat in 86 men. Test diets were an average American diet, a Step I diet and a Step II diet. The results indicated that dietary fat induced changes in the ratio of LDL:HDL were affected by genetic variants in the genes for apoE and 3-beta-adrenergic receptor related to a reduced ratio, and apoB and apoA-IV related to an increased ratio on a low-fat diet. The primary effect on responses was due to variances in the HDL cholesterol level. Lefevre, M., Roheim, P., Tulley, R.T. et al. Circulation 1998; 98: I-29 (Abstract # 0144).
A dietary fatty acid – apo A-IV-2 allele interaction affects cholesterol absorption. Previous studies have shown that variance in the apoA-IV gene alters cholesterol absorption rates in humans. In these studies the authors investigated whether the type of dietary fat affected the apoA-IV gene influences on cholesterol absorption rates. Cholesterol absorption was measured in 13 apoA-IV-1/1 homozygotes and 12 apoA-IV-1/2 heterozygotes fed a high cholesterol diet (750 mg/day) with either 35% total fat/15% SFA, 35% total fat/15% PUFA or 20% total fat. Both groups had similar cholesterol absorption rates with the high SFA (52%) and low fat (48%) diets; however, with the high PUFA diet the apoA-IV-1/1 had significantly higher rates of cholesterol absorption (57%) than the apoA-IV-1/2 group (48%). These data indicate that there is a significant dietary fat – apoA-IV gene interaction determining fractional cholesterol absorption that functions when the diet is high in PUFA. Weinberg, R.B., Hockey, K.J., Terry, J.G. et al. Circulation 1998; 98: I-30 (Abstract # 0146).
Triglycerides and HDL cholesterol, but not LDL cholesterol, predict high risk for ischemic heart disease as assessed by SPECT scintigraphy. This investigation utilized myocardial perfusion testing to determine the relationships between the plasma lipid and lipoprotein profile and ischemic heart disease in 30 patients at high risk for CAD and 30 matched controls with no perfusion defects. The investigators used stress nuclear perfusion imaging (SPECT) to classify subjects as either in the high or low CAD risk categories. The high risk patients had slightly lower LDL levels than controls (118 vs 130 mg/dl), lower HDL levels (39 vs 45 mg/dl) and higher triglycerides (189 vs 135 mg/dl). The high risk group had more smokers, diabetics and those with a history of CAD compared to controls while both groups had similar numbers of hypertensives (67%). The data suggest that in this group of normocholesterolemics ischemic heart disease is more related to a low HDL, high triglyceride lipid profile (dyslipidemia) than to an elevated LDL level (hyperlipidemia). Bybee, K.A., O’Keefe, J.H., Harris, W.S., et al. Circulation 1998; 98: I-45 (Abstract # 0220).
Seasonal variation of blood cholesterol levels. Seasonal variations in plasma cholesterol levels have been commented on for many years yet there are limited data on the magnitude of the changes. These authors followed 383 healthy subjects enrolled in a central Massachusetts HMO over the course of a year. During this period subjects had 4 or 5 blood samples drawn for lipid analysis. The data, when fit to a cosine model, indicated that the peak plasma cholesterol occurred in January with an increase of 4.2 mg/dl. BMI had the strongest relationship with plasma cholesterol levels and a 1 kg/m2 change was associated with a 4-6 mg/dl change in plasma cholesterol. The observed seasonal changes are lower than seen previously in cross-sectional studies (as high as 20 mg/dl) and may relate to the extent of weight gain between summer and winter assays for the various study groups. Irrespective, it seems clear that winter inactivity, plus holiday season excesses, boost not only body weights but also plasma cholesterol levels. Ockene, I.S., Stanek, E., Niclosi, R., & Merriam, P.A. Circulation 1998; 98: I-45 (Abstract # 0221).
Physical activity and risk of coronary heart disease among diabetic women. There is clear evidence of an association between exercise and lower risk of CHD in healthy populations but less information is available regarding diabetics. In this study of 4,151 diabetic female nurses (age 40-65 years), the authors followed the activity levels of this cohort over eight years and recorded 156 new cases of CHD. Activity levels were classified as metabolic equivalent hours (MET). The CHD relative risk for the multivariant adjusted quartiles of MET were 1.0, 0.80, 0.75, 0.67. The multivariate relative risk across categories of MET hours/week for walking were 1.0, 0.95, 0.61, 0.72. These data suggest that physical activity, including walking, has positive benefits in preventing CHD among diabetic women. Hu, F.B., Hennekens, C.H., Stampfer, M.J., et al. Circulation 1998; 98: I-375 (Abstract # 1967).
Dietary intake of specific saturated fatty acids and risk of coronary heart disease in women. Data from the Nurses’ Health Study were used to determine the relationships between specific dietary saturated fatty acids (SFA) and CHD risk. The cohort of 80,990 women, 34 to 59 years of age in 1980, were followed for 14 years. Food frequency questionnaires were collected at baseline and periodically during follow up and there were 939 of CHD events. In multivariant analysis CHD risk was not associated with intake of short and medium chain SFA (C4-C10). The CHD relative risk for a 1% increase in SFA calories were: 1.12 for lauric + myristic acids, 1.07 for palmitic acid, and 1.19 for stearic acid. The authors stated that a 5% increase in intake of all long chain SFA (C12-C18) resulted in a relative risk of 1.29. Interestingly, stearic acid, while not a plasma cholesterol raising SFA, had a similar effect on relative risk as the other SFA. Hu, F.B., Stampfer, M.J., Manson, J.E., et al. Circulation 1998; 98: I-515 (Abstract # 2709).
FINDINGS OF INTEREST
Lotufo et al. reported data from the Physician’s Health Study (n=19,112) indicating that increasing male pattern baldness was related to increased CHD events. Results were similar for non-fatal MI and angina. Risk associated with male pattern baldness was increased by hypertension or hypercholesterolemia. Circulation 1998; 98: I-168 (Abstract #868).
Sano et al. investigated the relationship between green tea consumption and coronary stenosis in a Japanese study. Data from 184 patients undergoing coronary arteriography indicated that green tea intake was inversely associated with coronary stenosis (odds ratio 4.4) while age (OR 1.1) and smoking (OR 3.1) were positively associated. Circulation 1998; 98: I-168 (Abstract #870).
Meinertz and Nilausen reported on of the effects of soy protein intake on Lp(a) levels in normocholesterolemic men and women. The results indicated that intake of untreated soy protein increased plasma levels of Lp(a) while ethanolic extraction of the protein abolished the Lp(a) elevating component. Untreated soy protein raised Lp(a) levels by almost 30%. Circulation 1998; 98: I-451 (Abstract #2373).
Rissanen et al. studied the relationship between fish oil derived fatty acids (docosahexaenoic, DHA, and docosapentaenoic, DPA, acids) and acute myocardial infarction in 1871 men. Fish oil intake was assessed by analysis of serum fatty acid profiles. The proportion of serum DHA and DPA was associated with reduced risk of MI. Men in the highest quintile for plasma DHA and DPA (>3.5%) had a 44% lower risk of MI than the lowest quintile. The men in the highest quintile also had higher plasma HDL levels, lower serum insulin levels, and lower platelet aggregability. Circulation 1998; 98: I-537 (Abstract #2823).
Vigilante and Flynn used a mailed survey to determine physicians’ nutrition knowledge regarding diet and hyperlipidemia. Eighty-two percent did not know that a low-fat diet would decrease HDL levels; 40% thought dietary fat raises plasma triglyceride levels; 70% defined a low-fat diet as having no more than 20% of calories from fat; and 30% failed to identify olive oil as a good source of monounsaturated fat. Clearly there can be problems with the NCEP recommendation that diet counseling by physicians serve as the initial treatment for lipid management. Circulation 1998; 98: I-584 (Abstract #3075).
Studies also suggest that risk of MI and sudden cardiac death in the elderly vary according to the day of the week and the season. Griska et al. reported that more heart attacks occur on Monday than any other day of the week while Sheth et al. noted that more heart attacks occur during December and January. Circulation 1998; 98: I-720 (Abstracts #3785 & #3786).
Editorial:
Paradigms Lost
It can be a worthy educational exercise to every now and then take a look at the past and present of our nutrition messages which can substantially change the public’s view of the food it buys and the meals it eats. For the diet-heart disease relationship there have been a number of intriguing transitions in our nutritional paradigms. In just the past decade we have subtly changed our nutritional messages to the public, and in most cases these changes have addressed many of the concerns raised about the old messages and improved how we communicate a positive nutritional message to the public. Let us consider the following.
[1] The bad saturated fat replaces the bad dietary cholesterol: It wasn’t that long ago that hydrogenated coconut oil, peanuts, vegetable shortenings, even soft drinks were promoted because they had “no cholesterol.” And the egg become the symbolic image of high blood cholesterol and increased risk of heart disease. It took considerable time, and for the public some less than useful dietary changes, but eventually the total fat, saturated fat message became dominant and consumers looked for more than the “cholesterol-free” banner in making its selections in the supermarket. But there is still a long way to go as I continue to hear consumers say “I love eggs, I just throw away the yolks,” or ask about the cholesterol content of walnuts or avocados. The public’s cholesterol-phobia is well ingrained.
[2] Emphasis shift from fat calories to total calories: The mantra heard just a few years ago was that if we could just reduce the percent of fat calories in the diet everyone would loss weight has fallen from grace with each report of the American obesity epidemic. Indeed the public did reduce their percent of fat calories, unfortunately by increasing total calories in the diet. So with more and more low-fat and fat-free foods in the marketplace we have a population getting progressively heavier and heavier. Now we must educate consumers that a low-fat (high sugar) product with 500 calories has just the same weight gain potential as the full-fat product with 500 calories. [“It’s the calories, stupid!”] So now we talk about total calories, with reduced emphasis on any single source of those calories, and the importance of caloric expenditure in weight maintenance. The evidence continues to build that exercise, even at modest levels, can significantly lower heart disease risk. What we now need to know is whether that means that a person of normal weight, who exercises frequently and is very fit, can skip the “sawdust and wood chips” diet.
[3] Change from emphasis on low-fat foods to an emphasis on fruits and vegetables: Somehow the shift from a high-fat, nutrient poor diet to a low-fat, nutrient poor diet just hasn’t done much for the nutritional well-being of the population. Sadly the low-fat message has had a much better hearing (and clearly a much better marketplace) than the “5-A-Day” message for fruits and vegetables. The change in nutrition education emphasis from a national fat-phobia to nutrient needs, and the value of B vitamins and antioxidants, can only be viewed as a long overdue positive shift in our educational efforts. As fat restrictions were pushed lower and lower, the public consumed more and more sugar while losing sight of the importance of nutrient dense foods and their contributions to health. The shift towards the “5-A-Day” message in place of a single minded obsession with low-fat, low-cholesterol avoidance should make a real impact on heart health and disease prevention.
[4] From exclusionary to inclusionary dietary advice: At one time the only nutritional advice many consumers heard was “don’t eat this and don’t eat that.” Unfounded food fears shaped the diets of many Americans, and many high quality food items were summarily banned from kitchen pantries. There still exist those who publish lists of foods one should never, ever eat with scare labels like “heart attack on a plate” but overall the profession today does a better job of communicating what a healthy diet should contain and how to make dietary changes which maintain nutritional balance. While some still cling to an archaic “good-food, bad-food” paternalism, nutrition professionals have evidently learned that consumers want to know what a healthy diet should have in it and that the ancient concepts of balance, variety and moderation still serve some purposes.
We eat foods, not nutrients, and our professional set of numerical goals for the national diet certainly needs some explaining to the public in a way that they can understand, accept, live with, and welcome. These paradigm shifts go a long way in easing the public’s food fears and hopefully will shift each meal from a life and death decision to something that can be eaten and enjoyed.
Donald J. McNamara, Ph.D.
Executive Editor, Nutrition Close-Up
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 subscription for the newsletter by contacting the ENC.
