Published: February 9, 2020 | 5 mins read
Dietary Citrates & Kidney Stones
Prevention is the goal of every kidney stone sufferer. However, one often overlooked hero in preventing kidney stone formation is citric acid. You’ve probably heard about citric acid already. But this blog will explore deeper on the role of citric acid in your prevention plan. Also, we will provide tips on how to incorporate it into your diet to combat kidney stones.
What is Citric Acid?
Citric acid is a natural organic acid found in various fruits, mainly citrus fruits like lemons and limes. It is also available in synthetic forms, such as calcium citrate and potassium citrate. However, the bioavailability of citric acid is highest in natural food sources. Here are some options where you can find citric acid:
Fruits, particularly citrus fruits: Limes and lemons are excellent sources of citric acid, while considered very low in oxalates (around 1mg oxalate per 100g). Incorporating these fruits into your diet can provide you with the benefits of citric acid.
Natural supplements: For people who are sensitive to lemon or other citrus fruits, as they may erode tooth enamel after long-term use, we suggest freeze-dried lemon in capsule form.
Synthetic forms: Calcium citrate and potassium citrate supplements are also available as alternatives for those who have difficulty consuming citrus fruits.
Citric Acid and Kidney Stones
Each type and sub-type of kidney stones form due to various factors, each with unique characteristics. However, these particular stone types can be prevented by citric acid:
Calcium Oxalate Stones
These stones are the most common type and form when excess calcium combines with oxalic acid in the urine. Oxalate-rich foods, such as spinach and rhubarb, contribute to the formation of these stones.
Calcium Phosphate Stones
Alkaline urine, calcium, and phosphoric acid form these kidney stones. A diet high in plant foods can increase the formation of these stones due to their alkaline properties.
Uric Acid Stones
When urine becomes too acidic, and there are high levels of uric acid present, uric acid stones can form. Western medicine and mainstream media often blame meat-rich diets for this stone type. However, this is not the case. In fact, low urine pH (<5.5) is the real culprit behind this caused by metabolic dysfunction. If pH is maintained at neutral levels (around 6.0-7.0), you won’t form uric acid stones even if you consume a lot of meat.
To better understand how each stone type and sub-type forms, check our Kidney Stone Identification Page here.
How does citric acid work to prevent kidney stones?
Citric acid is a powerful protector against kidney stone formation. It makes urine less favorable for stone formation in general. According to research conducted on 135 subjects, 85% who consumed citric acid or citrate successfully blocked stone formation. In contrast, the placebo group experienced a 52% formation rate of new stones.
Here’s how it does the magic:
1. Binds with calcium
Citric acid directly binds with calcium. Thus, it prevents other stone-forming materials like oxalates from binding with calcium and forming stones.
Additionally, citrate helps boost the activity of a protein called Tamm-Horsfall Protein (THP). This is a glycoprotein (a type of protein with attached carbohydrate molecules) exclusively produced in the ascending limb of the loop of Henle (a U-shaped structure found in the functional unit of the kidney). It is the most abundant protein in normal urine. And, it is vital in many healthy kidney functions and kidney stone prevention.
THP helps regulate calcium and phosphate in the kidneys. It also binds with calcium ions, preventing their precipitation and the formation of calcium-containing crystals. As a result, it hinders the development of calcium-based kidney stones.
Furthermore, as citric acid binds calcium, it helps reduce the activity of another glycoprotein called osteopontin. This protein is known to interact with calcium to aid formation, growth and hardening of crystals. Actually, the role of osteopontin in kidney stone incident remains controversial as some research says it promotes stone formation, while others claim otherwise.
2. Alkalizes the urine towards neutral
Citric acid increases the pH level of urine, making it less acidic. This helps inhibit the formation of uric acid stones, which thrive in an acidic environment. Again, acidic urine (<5.5 pH) is the primary reason uric acid stones form.
How to use citric acid?
Incorporating citric acid into your diet doesn’t have to be a daunting task. Here are three simple ways to make it a part of your daily routine:
Juice 1-2 lemons or limes per day: Squeeze fresh lemons or limes and consume the juice. Approximately 1-2 lemons or limes per day can provide you with a similar amount of citrate found in therapeutic doses of synthetic citrate (around 1200 mg).
Store freshly squeezed lemons in the refrigerator: If you prefer to prepare a larger batch, freshly-squeezed lemon or lime juice can be stored in the refrigerator for a day or two. You can add it to water, tea or put it into various recipes to enjoy its benefits.
Natural supplements: Natural supplements, like our product CLEANSE, contain citric acid from freeze-dried whole foods. Freeze-drying, unlike heat-drying, keeps the nutrients bioavailable. So, natural supplements are great options for people who are busy, traveling or have sensitivities.
Remember, citric acid is a powerful ingredient in our kidney stone prevention plan. Always opt for freshly-squeezed lemon juice or natural supplements over bottled alternatives, as pasteurization affects the bioavailability of citric acid. Also, natural is always better than synthetic (a.k.a. citrate). Incorporating natural sources of citric acid into our diets is surely an effective and refreshing way to keep kidney stones at bay.
- Citrate to Prevent Calcium and Uric Acid Stones
- Citric Acid and Kidney Stones
- Urinary citrate and renal stone disease: the preventive role of alkali citrate treatment
- Osteopontin: An important protein in the formation of kidney stones
- Can urine osteopontin levels, which may be correlated with nutrition intake and body composition, be used as a new biomarker in the diagnosis of nephrolithiasis?