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Journal of Endourology
J Endourol. Apr 2009; 23(4): 715–717.
PMCID: PMC2827241
NIHMSID: NIHMS174196

Is the Internet a Reliable Source for Dietary Recommendations for Stone Formers?

Abstract

Purpose

Kidney stone formation is influenced by environmental factors, especially diet. Certain dietary modifications, including increased fluid intake, reduced animal protein and sodium consumption, and normal calcium intake, reduce the risk of stone activity. Patients frequently use the Internet for information regarding disease processes. We undertook this study to determine the quality of dietary stone information available in this communication domain.

Methods

The Google search engine was used to survey 458 consecutive sites related to kidney stones and dietary information. The presence or absence of the four aforementioned dietary recommendations was recorded. The sites were analyzed for correctness, information on all four domains present and correct; inaccuracy, something mentioned about all four areas but ≥1 recommendation error(s); deficiency, information on ≤3 or domains and no recommendation errors; deficiency and inaccuracy, information on ≤3 areas and ≥1 recommendation error(s).

Results

  Web sites
Correct 80 (17.4%)
Inaccuracy 10 (2.2%)
Deficiency 365 (79.5%)
Deficiency/inaccuracy 3 (0.7%)
Total 460

There were 10 errors regarding calcium intake and 2 pertaining to protein consumption. The quality of information varied with the reporting source.

Conclusions

Internet-based information regarding four important dietary modifications for kidney stone formers is frequently incomplete. Dietary inaccuracy, while uncommon in this communication domain, is mostly centered on the misconception that calcium restriction is beneficial. The quality of dietary information may depend on the Internet information source.

Introduction

Nephrolithiasis is influenced by genetic and environmental factors—diet being the major environmental component. There is robust epidemiologic evidence that diet influences stone formation. Curhan and associates14 have published on the relationships of dietary habits and stone risk in three large epidemiologic cohorts, Nurses Health Study 1, Nurses Health Study 2, and the Health Professional Follow-up Study. They have demonstrated that in some or all of these cohorts increased fluid and dietary calcium consumption was associated with a reduced risk of incident kidney stone formation, while increased intake of animal protein, fructose, and oxalate increased stone risk. Prospective randomized studies have demonstrated that dietary modifications can reduce recurrent kidney stone formation. Borghi and associates 5 performed a study in which first time calcium oxalate stone formers were randomized to either receive instructions or not receive instructions on increased water consumption. The former group had a significant and durable increase in urine volume as compared with the latter cohort. In addition, stone recurrence was lower in those instructed to consume more fluid. Borghi and colleagues 6 also conducted a randomized study in which recurrent hypercalciuric stone formers were randomized to consume a diet with reduced sodium and animal protein and normal calcium content, or one with reduced calcium intake. The first group had fewer subsequent stone events.

A significant proportion of the population of the United States uses the Internet for information regarding disease processes, including preventive measures. The Pew Internet Project survey showed that 80% of the adult American population uses the Internet daily. Eighty percent of these Internet users, or some 113 million adults, search for information on health-related topics. 7 Therefore, the accuracy of information provided by this medium may be important. We undertook a study to determine the accuracy and quality of dietary information provided on the Internet for kidney stone prevention. We focused on the four modifications for which there is level 1 evidence demonstrating a reduction in recurrent stone formation increased fluid intake, normal calcium consumption, reduced sodium intake, and reduced animal protein consumption.

Methods

Web sites related to kidney stones and dietary information were surveyed using the Google search engine and the term “Kidney stones and dietary recommendations.” Five hundred Web sites were surveyed, and after excluding duplications, 458 consecutive sites related to kidney stones and dietary information were evaluated for authorship and content. The presence or absence of the aforementioned four dietary recommendations was recorded as well as any contradictory information that we considered as errors. The results were stratified by dietary recommendation and site source. The sites were stratified into the various categories as shown in Table 1. General medical were informational or news-based sites. Institutional were defined as sites sponsored by a hospital system or a governmental agency. Urology and nephrology sites were defined as those originating from either a private or academic urology or nephrology practice, respectively. Nonurologist/nephrologist were sites generated by physicians with either private or academic affiliation who were medical doctors (M.D. or D.O.) specializing in areas other than urology or nephrology. Commercial represented any site marketing or selling a product. Nutritionist were sites sponsored by individuals or agencies with formal educational background in nutritional sciences. The sites were analyzed for correctness, information on all four domains present and correct; inaccuracy, something mentioned about all four areas but ≥1 recommendation error(s); deficiency, information on ≤3 domains with no recommendation errors; deficiency and inaccuracy, information on ≤3 areas and ≥1 recommendation error(s). The Internet information was considered correct when it was formulated in accordance with the present generally accepted view of which dietary advice that should be given to calcium stone formers.

Table 1.
Sites Surveyed by Source Type

Results

Table 2 shows the data stratified by source. Across all Web sites, correct information was provided in 15% to 50% of sites. In a simple comparison of the proportion of correct responses for each type of Web site, an overall significant difference (p < 0.001) was found. Urology and nephrology Web sites provided correct information on 41% and 51% of the sites, respectively. All the other types of Web sites contained correct information on only 13% to 16% of the examined sites. Results stratified by dietary recommendation are depicted in Table 3. There was an overall significant difference (p < 0.001) in the comparison of the proportion of correct dietary recommendations. Fluid and protein were equivalently recommended 52.6% and 50.2% of the time, respectively. However, the percentage of correct recommendations for sodium (40.2%) and calcium (32.3%) were significantly lower.

Table 2.
Results Stratified by Source
Table 3.
Results Stratified by Recommendation

Discussion

The Internet has developed into a widely popular and available tool for gathering information. The Pew Internet and American Life Project is a survey that tracks Americans' use of the Internet through phone and online surveys.710 It reveals that 80% of Internet users, 113 million Americans, search the Internet for healthcare information. Forty-four percent of users have searched for dietary recommendations. When searching for specific healthcare topics versus general medical topics, women use the Internet with a higher frequency than men (72% v 54%). College graduates are more likely to search than high school graduates (68% v 52%). Not surprisingly, Internet users who have seen a physician within 1 year have searched for information at a higher rate than individuals who have not seen a physician (68% v 45%). This correlates to Internet users with a chronic medical condition search more often than healthy individuals (85% v 61%). Seventy-three percent of health information seekers feel that the Internet has improved the level of healthcare they receive. The healthcare information available has prompted 53% of seekers to reportedly change their behavior in a manner that would benefit their level of wellness. Fifty-eight percent of respondents turn to the Internet first for information versus 35% who first obtain information from a medical professional. Sixty-six percent of seekers begin with a search engine. Eighty-one percent of Internet users believe that the information uncovered is reliable, while only 15% check the source or the date of the information.

There is compelling evidence that certain dietary measures limit the risk for stone formation.1,2,5,6,11 These modifications should be first-line therapy for the majority of stone formers as they are safe, are inexpensive, and may be effective. Increased fluid consumption usually results in higher urine output and reduction of the supersaturation of stone-forming salts. 5 Minimizing sodium intake results in reduced calcium and cystine excretion, and increased citrate excretion. A reduction in animal protein consumption has been shown to reduce calcium, uric acid, and potentially oxalate excretion while increasing citrate excretion and urinary pH. 11 Maintenance of normal dietary calcium consumption is recommended as it helps maintain skeletal integrity and may reduce stone risk. While reduced calcium consumption reduces calcium excretion, it promotes oxalate excretion. The latter is thought to be due to reduction in calcium–oxalate complexes in the intestine promoting the absorption of oxalate from the gastrointestinal tract and subsequent renal excretion. 12 We did not analyze the quality of Internet information regarding oxalate, citrate, and fructose consumption in this study as we focused on dietary modifications supported by level 1 evidence. However, analyzing the quality of available information on these nutrients may be warranted in the future. Unfortunately, Internet-based information regarding fluid, sodium, protein, and calcium intake is frequently incomplete. Dietary inaccuracy, while uncommon in this communication domain, is mostly centered on the misconception that calcium restriction is beneficial. However, the Internet offers instant access and unlimited dissemination of information. It has the characteristics of being interactive, allowing one to search and sort through vast amounts of information. These traits give it the capacity to respond to individualized informational needs; however, this information lacks the safeguard of peer review and varies by source. With this in mind, we are currently in the process of implementing an interactive Web site for stone formers. It will provide tailored dietary information and instructions for each category of metabolic stone former. It will have the capacity to provide individual feed back to each patient concerning his/her actual caloric intake. This interact model has demonstrated modest improvements in compliance and outcomes in diabetes 13 and chronic obstructive pulmonary disease management. 14

Disclosure Statement

No competing financial interests exist.

References

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