Nutritional strategies to prevent urolithiasis are useful when there is a diet-related contributor. They may target urine volume/concentration, pH, and the urinary excretion of salts and other compounds that either promote or inhibit formation of various types of calculi. As needed, strategies are implemented to mitigate specific altered physiological function or other factors (underlying infection, for example, or altered gastrointestinal function, mineral metabolism, nutritional status, or nutrient handling) and to induce favorable changes in behavior and/or attitudes about food. Additionally, as more is learned about stone disease and gut and urinary microbiota, nutritional strategies exploiting host microbial systems to prevent stones will be developed.¹ Customized nutrition strategies, ie, those tailored to each patient’s risk factors, are preferable as they usually require fewer changes than broad nutrition guidelines that may or may not address an individual’s particular risk factors.

Individualized dietary management for stone prevention requires knowledge of how the patient eats. This allows for potential stone risk triggers to be identified (see Figure). Other helpful knowledge for dietary management includes patient medical and medication histories, 24-hour urinary stone risk parameters, other stone-related biochemistry, and stone history (eg, stone composition, whether familial/genetic influences are suspected, aggressiveness and frequency of stone disease).

The Figure lists conventional evidence-based nutrition strategies for stone prevention; newer concepts include:

1. Dietary patterns vs specific foods. Large organizations such as the American Heart Association, the American Cancer Society, and the Academy of Nutrition and Dietetics have produced recommendations for broad eating habits vs specific foods.² Similarly, the U.S. Department of Agriculture’s Dietary Guidelines for Americans (available at https://health.gov/dietaryguidelines/2015/guidelines/chapter-1/) have shifted over time from single nutrients and foods toward overall dietary patterns. These changes were driven by evidence that overall dietary patterns more strongly correlate with health³ and health-related quality of life than the presence or absence of individual foods and nutrients, due in part to the synergistic effects of individual foods and their associated nutrients. For stone prevention, diets rich in potassium, calcium, phytate, fiber, fluids, bicarbonate precursors, and whole or fresh vs processed foods are recommended.⁴ This may mean focusing more on what patients should be eating vs what they shouldn’t.
2. Nondairy strategies for calcium consumption. For various reasons, consumption of dairy by many Americans is declining.⁵ Dairy was historically the primary source of calcium, contributing up to 75% of all calcium consumption; alternative sources are now needed. Fortunately, there are plenty of commercially available nondairy calcium sources. These include calcium-fortified plant-based milks, many of which are fortified with calcium to a higher degree, gram for gram, than naturally occurs in dairy milk. A 6-ounce serving of a plant-based milk, for example, typically provides ≥300 mg of calcium. When consumed 3 times daily, such as 1 serving with each meal, adequate calcium intake while lowering dietary oxalate absorption may be possible.
3. Culturally responsive nutrition recommendations. This is a primary focus in clinical nutrition today driven by respect for diverse cultural identities and knowledge that most traditional dietary patterns can be made healthy. Stone-preventive patterns that respect culturally based habits are no exception. Dietary patterns devoid of dairy, for example, can be made ample for calcium with nondairy sources (see above). Dietary patterns rich in oxalate (eg, traditional Mexican diets with staples such as beans and corn) can be optimized for calcium to tip the balance away from higher oxalate absorption. Culturally responsive management of dietary stone risk factors should aim to attenuate effects of staple foods rather than eliminate them; this is an area of emerging interest.
4. Stone-specific dietary assessment tools. Clinician-delivered diet assessment, education, and counseling improve cardiometabolic risk factors.⁶ Other data demonstrate that intensive counseling involving nutrition specialists increases dietary quality particularly by increasing fruit and vegetable consumption.⁶ Yet many barriers prevent widespread clinical nutrition assessment and counseling. Rapid dietary screening tools, perhaps embedded in electronic health records and mobile technologies, are therefore desirable. Particularly appealing would be tools that target stone-related dietary risk factors. While some tools are in development, more intensive research on flexible yet accurate assessment methods for stone prevention are needed.
5. Over-the-counter alkali. Partly in response to higher costs for prescriptive alkali, the number of over-the-counter products aimed at raising urine citrate and/or pH has risen. Most contain various citrate and bicarbonate salts as well as citric acid. Many forms are available, including powders to be dissolved in fluids, ready-to-consume beverages, and tablets and gummies. In addition to these products, some sugar-free soft drinks and drink mixes are also rich in citrate and other organic acids with bicarbonate potential. Recent studies and those underway are providing data to evaluate the effectiveness of these products.⁷
6. Diet-related assistive technologies. Various meal-planning apps and those designed to induce behavior changes are now available and used by many patients. Some find value in use of nutrient and calorie counters, diet trackers and reminders, and/or “smart” technologies, such as to increase fluid intake.⁸ While these may appeal mostly to more youthful or “tech-savvy” patients, their potential to aid adherence to stone prevention nutrition recommendations is significant. More research to confirm their utility is needed and, indeed, is underway.
7. Online nutrition counseling. While routine during the COVID-19 pandemic, online clinical encounters may never completely subside. However, they may not be as effective. Some studies demonstrate effectiveness of nutrition counseling in virtual visits.⁹ But others demonstrate lower patient engagement and potentially lower effectiveness, such as for weight loss.¹⁰ Efforts to optimize patient education, willingness to change, and motivation in this setting are thus needed.
8. Personalized and value-based approaches to nutrition care. Patients’ dietary patterns reflect personal, cultural, and societal inputs, including food-related knowledge, intrinsic motivational factors, food likes/dislikes and intolerances, individual nutrient needs, access to food and food storage space, food preparation and meal planning skills, economic status, aspects of the built environment (eg, density of fast food and supermarkets, advertising), occupational factors (eg, shift work, eating/drinking limits), religious and spiritual practices, nutritional requirements for managing other diseases, family expectations, and peer pressure. Considering these factors when devising nutrition regimens may optimize stone prevention efforts.