In this cross-sectional study of the United States population, we found that a healthier diet, as determined by the USDA HEI, was associated with lower self-reported LUTS in men over the age of 40 years. Alternatively, we found no evidence that any individual food group appeared to be protective from LUTS. We also found evidence of greater self-reported LUTS in blacks and Hispanics and reduced LUTS in patients who consumed alcohol.
There is a relative paucity of literature evaluating the association between diet and LUTS, and the findings of these studies are heterogeneous and conflicting. A 2008 study by Kristal et al that analyzed the incident cases of BPH among patients assigned to the placebo arm of the prostate cancer prevention trial found that a diet that included moderate alcohol intake and was high in protein and vegetables and low in fat and red meat was protective for LUTS.8
A study by Chyou et al found that beef intake slightly increased the risk of LUTS, although analysis of 32 other food groups found no increased risk.9
Analysis of the Health Professionals Follow-up Study found that vegetable intake was inversely correlated with LUTS, but other food groups showed no strong association.10
In other studies, starch, vegetable consumption, fat consumption, and poultry have shown to increase the risk of BPH and LUTS,15-17
whereas others have shown vegetables and unsaturated fats to be protective from LUTS. The heterogeneous patient populations, definitions used for LUTS, and analytic methods used make it difficult to draw any clear conclusions.
We used the HEI scores generated from the NHANES 24-hour dietary data. Use of the HEI has many advantages. First, the HEI uses an easily interpretable scoring system based on adherence to USDA dietary recommendations that precorrects for such factors as total caloric intake, body size, age, and individual recommended serving amount.12
This makes comparison of the numbers between subgroups potentially easier. Second, the scores have been shown in other studies to correlate with the development of chronic diseases, most importantly cardiovascular disease.18
Third, unlike other dietary studies that analyze individual components of diet for correlation with disease, the HEI is intended to analyze the overall healthiness of the study participant’s diet. Although this can be viewed as a weakness of using the HEI, as it does not easily allow one to study the effects of manipulating 1 dietary variable to lower LUTS (ie, studying the increase in vegetable consumption), use of the overall HEI may represent a more real-world dietary situation, in which increasing or decreasing a single dietary component may not be expected to influence disease processes if the overall diet remains poor.
How diet affects the development of LUTS is unclear, but there are potential mechanisms that have been proposed. Oxidative stress within the prostate has been shown to increase the development of BPH19
; thus healthier foods with higher levels of antioxidants may decrease LUTS. This relationship has been described in a previous observational study where diets rich in the antioxidants obtained from vegetables, namely β
-carotene, lutein, and vitamin C, protected participants from LUTS.20
The autonomic nervous system can also be influenced by diet,21
and increased sympathetic tone has been linked to the development of LUTS. A study by McVary et al showed that sympathetic tone directly correlated with increasing American Urological Association Symptoms scores.4
A similar link between catecholamines and life stress as it relates to urinary symptoms has been described.1
Finally, androgens, which are necessary for prostate growth and likely play a role in BPH development through influences of prostatic growth factors,22
are another possible dietary mechanism for LUTS development. Androgen levels can be influenced by diet, likely by dietary affects on the circulating sex hormone binding globulins,23
which alter the bioavailability of circulating androgens. A decrease in the bioavailability of testosterone relative to estrogen levels has been shown to influence prostate growth.5
The findings of an inverse correlation between both alcohol intake and exercise and LUTS have been reported previously in similar study populations.8
Only alcohol intake was significant on multivariate analysis, but both exercise and alcohol intake were highly correlated with a healthy diet.9
Overall, these findings support a theory that a lifestyle that includes a healthy diet, exercise, and moderate alcohol intake, may decrease the risk of LUTS. Further study of how these three variables work together in the individual to decrease LUTS is certainly warranted.
The relationship between race and LUTS was an intriguing finding from the study that has been suggested before.24,25
Confounding variables that were not included in this analysis but have been shown to effect LUTS, including socioeconomic status and education, may explain some of the differences we found between races.26
A further consideration, however, might be that the differences in LUTS reported between levels of socioeconomic status and education may be in part influenced by known differences in diet, although this theory requires further investigation.
Our analysis has several limitations that warrant brief mention. Our data are cross-sectional in nature, and although they can demonstrate associations between diet and LUTS, they cannot show conclusively a causal relationship between diet and LUTS. Our definition of LUTS was based on only 2 self-reported questions that have not been validated to describe all LUTS/BPH patients. Having a more precise questionnaire, such as the American Urological Association Symptom Index, would certainly allow a better understand of the relationship between diet and LUTS. In addition, with such few men reporting 2 symptoms (n = 59), we were unable to demonstrate a dose-dependent relationship between LUTS and diet that should exist if diet is truly causal.
The HEI scores used NHANES 24-hour dietary recall data that, although excellent at accurately capturing the individual’s previous day’s food intake, are not as accurate when used to extrapolate dietary intake over the entire year. However, with large populations such as those used in the NHANES, a valid description of average intake for the entire cohort has been shown to be possible.27
Finally, the overall HEI score represents 10 dietary components, determined by the USDA to be important aspects of diet that are all equally weighted. However, this weighting may not accurately reflect what represents the components of a truly healthy diet and may be culturally biased.26
Despite these limitations, our analysis is noteworthy for its methodological rigor and use of contemporary and highly generalizable US data. Our finding of a nearly 70% reduction in the odds of LUTS among patients with the healthiest diet needs further confirmation, but suggests that diet alteration may be a potential option in the management of this common and bothersome symptom.