High quality dietary patterns, characterized by adherence to sodium restriction and nutrients promoted in the DASH eating plan and consumption of omega-3 fish oils, have been associated with decreased risk and improved management of cardiovascular disease risk factors and conditions, including heart failure.2–8,11,12
This analysis demonstrates that the dietary quality of U.S. adults living in the community with heart failure is poor. It is likely the poor dietary patterns observed in the population began many years before diagnosis of heart failure, and in fact contributed to the development of heart failure.21
Indeed, studies examining adherence to DASH diet recommendations in populations at increased risk for developing heart failure (i.e. hypertension and atherosclerosis) have observed poor dietary quality.22,23
This study extends previous results by documenting that among persons with a severe chronic illness, namely heart failure, poor dietary habits persist. Our findings reinforce the need for primary prevention efforts aimed at improving dietary quality for cardiovascular disease risk reduction.
Sodium restriction is the mainstay of heart failure dietary recommendations,9
yet adherence to established guidelines was poor. Because of impaired neurohormonal regulation of sodium excretion, patients with heart failure must attain a dietary sodium intake that is less than that of the general population.5
The average daily sodium intake among persons with heart failure in this analysis was 2,728.5 mg/day, with 34% achieving the 2,000 mg/day benchmark. The average daily sodium intake in the adult 1999–2006 NHANES sample age 50 and over without heart failure was 3,073.1 mg/day (data not shown). Results suggest that even though sodium intake among persons with heart failure remains high, there has been some success in decreasing sodium intake among persons with heart failure at the population-level.
Sodium restriction is challenging because it limits restaurant fare and convenience foods. Further, it requires careful label reading and food preparation. This analysis found that persons with hypertension consumed approximately 200 mg/day less than those without it, suggesting modest success of clinical and public health efforts to decrease sodium consumption in this at-risk group. Men and persons of lower education and income level had high sodium intake whereas persons of higher educational attainment and persons with higher income levels had lower sodium intake in this analysis. Educational attainment may be associated with better ability to read and understand food labels, while persons with higher income are allowed more choices about the foods that they purchase and consume. Targeted clinical efforts may be required to address differences in sodium intake according to socio-economic status indicators (education and income) and gender. However, given the widespread use of sodium in the food supply, any meaningful strategy to reduce sodium intake must rely upon a public and professional demand that manufacturers and restaurants reduce the amount of salt added during food preparation.
Potassium intake is of concern in heart failure. Low serum potassium has been shown to increase disease progression and increase all-cause mortality in persons with heart failure.24
Heart failure and its associated medications may alter serum potassium through changes in renal clearance and in the amounts and impact of aldosterone, renin-angiotensin and catecholamine secretions. Potassium deficiency in heart failure may result from a poor diet, anorexia, hyperaldosteronism, or through the use of loop or thiazide diuretics.25
Thus, eating high-potassium foods is recommended for many patients with heart failure. However, due to the risk of hyperkalemia in patients on potassium-sparing diuretics and those with renal failure, dietary potassium intake needs vary considerably, making it difficult to establish a universal goal. The results of this study demonstrate that overall, dietary potassium intake in persons with heart failure is low and that intake does not differ according to diuretic use. Because potassium has a narrow range and delicate physiological balance, potassium levels should be closely monitored for physicians to make individualized recommendations.
Calcium intake in this study was also inadequate. Calcium is essential for many regulatory functions affecting heart health, including coagulation/hemostasis, endocrine, exocrine, and neuroendocrine cell secretions, and actions of cardiac and skeletal muscles.26
Dietary calcium is implicated for its beneficial role in heart failure, as part of electrolyte balance to help maintain optimal heart contractility and rhythm, and blood pressure measures.27
Calcium appears to have a stabilizing effect on muscle contraction to prevent vasoconstriction in “calcium sensitive” hypertensives.27
Calcium may also directly inhibit renal sodium reabsorption, and/or lower the activity of the renin-angiotensin system to benefit hypertension.28
Unfortunately, loop diuretics may cause hypocalcemia.29
Thus, insufficient intake of calcium, flagged by the 2005 Dietary Guidelines for Americans (DGA 2005) as a nutrient of concern for most Americans,30
is of particular concern among persons with heart failure.
The DGA 2005 also named magnesium a nutrient of concern.30
Magnesium primarily affects cardiovascular, neuromuscular, and renal tissues. Magnesium intake may temper the increased arrhythmic risk and vasoconstriction experienced by many heart failure patients.6,31
Magnesium deficiency can lead to increased sodium retention, decreased potassium uptake, and affect essential intracellular calcium concentrations, all of which further complicate the management of heart failure. Persons taking loop and/or thiazide diuretic treatments for heart failure may need an even higher magnesium intake to address increased urinary excretion of magnesium caused by these medications.
Fiber intake was also inadequate. Fiber can impact inflammation, weight, blood pressure, glycemic control, and other cardiovascular disease biomarkers.32
Because fiber can be a dietary addition, rather than a restriction, adherence to this goal may be enhanced if routinely recommended.
Omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from fish, have been shown to suppress inflammatory markers and increase adiponectin for patients with heart failure.18,19
Since fish is a source of protein, potassium, and omega-3 fatty acids, following the AHA recommendation to eat at least two fatty fish meals per week may increase adherence to several nutrient goals. Only a small percentage of the NHANES study sample met intake goals for saturated fat. A cornerstone of dietary recommendations for persons with cardiovascular disease, excess intake of saturated fat has been directly correlated with increased LDL cholesterol,33
and increased levels of proinflammatory cytokines.7,34–37
A low saturated fat diet is particularly important in heart failure, to address a markedly increased risk for cardiovascular disease complications.
Protein energy malnutrition is generally not of concern in the U.S. population,38
yet 27% of this population did not achieve the DASH benchmark of 18% of total calories. Because common protein sources include foods that are also high in saturated fat (e.g. red meats) and sodium (e.g. processed meats), public health messages should reinforce the importance of obtaining protein from food sources that are otherwise beneficial.
Cholesterol presents an interesting case among dietary recommendations. It has not been definitively linked, as has saturated fat, with a detrimental lipidemic effect, because it tends to raise both LDL and HDL cholesterol.39
Studies suggest that the association between dietary cholesterol and occurrence of heart disease is small;40,41
and of the nutrients listed above, cholesterol is probably the least important. However, given that patients appear to be at least somewhat (40%) adherent to this recommendation, it may present an opportunity to impact other beneficial nutrients since lowering dietary cholesterol might reduce the intake of foods that also contain saturated fat.
This study has several limitations. The sample size (n
574) was relatively small. Self-reported diagnosis may under-estimate the true proportion of the population that has chronic heart failure.42
It is possible that the dietary status of persons who do not report having heart failure, either by choice or because they do not know or understand that they have the disease, is even poorer than what was observed. This study is cross-sectional, so change in dietary habits as a result of diagnosis is unknown. Dietary recall data have limitations. People tend to under-report consumption of calories and certain nutrients, including saturated fat and sodium, which would point to even poorer intake.43,44
Diet was assessed by a single 24-hour dietary recall. Though a single 24-hour dietary recall is not suitable for assessing individual intake, it is appropriate for determining group means.45
Doses and timing of dose changes were not available, nor were blood levels of potassium, sodium or other nutrients, so diuretic influence upon physiological status could not be determined. Data were not available for supplemental potassium and calcium consumption, over-the-counter calcium supplements or salt-substitutes with potassium. Thus, the results presented likely under-estimate total consumption and represent intake through diet. Data were also not available for heart failure symptoms. The fact that almost half of patients were not on a diuretic implies that they did not have symptoms. However, sodium consumption did not differ by diuretic status, suggesting that intake did not differ by symptom status.
The results of this study suggest that the dietary quality of persons with heart failure is poor, which has strong potential for detrimental effect on disease progression and underlying conditions. Numerous approaches will likely be required to address this issue. Patients need clear and simple dietary prescriptions for specific foods and food groups from health care providers. Moreover, effective, large-scale intervention strategies are needed11
because making dietary changes, even in the presence of life threatening illness, is extremely difficult.46
Such strategies should address both primary and secondary prevention. Results also support the need for public health approaches. In particular, since non-discretionary sodium added to foods is so prevalent, increased public and political pressure is needed to make changes to the food supply to improve the diet of persons with heart failure and the population in general.