I love the blurry pixillated image of OTC medication crowded onto shelves. Somehow it conveys armies of hopefuls pushing forward into the harried buyer who wants a remedy. The title points to 9 hopefuls for kidney stone prevention.
WHAT AM I OFFERING?
My friends at the kidney stone center at University of Texas Southwestern Medical School just published a wonderful paper detailing just how much citrate alkali is in each of the current OTC remedies, and I want to bring their work to all of you who read this site.
Some OTC Remedies Contain Two Alkali
All of the remedies contain some alkali as citrate. Potassium citrate tablets, the standard medically prescribed alkali tested in trials against stone formation, are only potassium citrate. In some OTC products some alkali comes not from citrate, but also from bicarbonate.
Citrate produces new bicarbonate in the blood as it is metabolized by cells. That is a process that takes some time. Bicarbonate is the prime alkali in blood and acts as soon as it is absorbed by the GI tract. So for a given amount of alkali the two forms will produce a different time pattern of urine pH and perhaps citrate – Citrate being presumably more stable, bicarbonate more peaks and valleys.
The Two Alkali May Not Confer Equal Protection
The 24 hour urine stone risk will not disclose whether the alkali has been steady or spiky. All it can tell us is the average for the 24 hours. This is the same limitation we face for fluids, calcium, even supersaturation.
But – that word! – we have no trials for sodium or potassium bicarbonate as stone prevention, only potassium citrate. The peaks and valleys might compromise protection. The Dallas article, by purifying the alkali measurement, literally begs the obvious question. Could simple potassium bicarbonate prevent stones? So inexpensive an agent, were it effective, would surely benefit all stone formers who could benefit from alkali. That remains for some future research.
The Benefits of Alkali
As I detail below, there are two. If urine pH needs raising, as in uric acid stone formers, these products may well be sufficient – dosage is not as simple as with prescribed K citrate, a matter noted in the individual product reviews. Alkali can raise urine citrate excretion, the other benefit. How and to what end is discussed below.
Why, then, put this here?
Because at least one person, highly educated, did not notice the citrate effect, and therefore it needs repeating.
First, the proper names of each one: Moonstone® Powder; Litholyte® Powder; Litholyte® Coffee; Kidney COP®; KSP tabsTM; LithoBalanceTM; NOW® Potassium Citrate; Horbaach® Potassium Citrate; TheraLith XR®. With apologies, but understandably, I abbreviate their names here (In order of their proper names): MSP; LLP; LLC; KCOP; KSP; LB; NOWPC; HORPC; TLY.
What They Can Do
Lets be clear. All of them have only one established medical benefit for kidney stone disease – alkali. Alkali when absorbed or when produced by metabolism of citrate, signals the citrate transporter to release into the urine citrate that has been filtered at the glomerulus. The linked article details citrate regulation and how potassium citrate pills – the conventional prescribed form of alkali – work.
The nine remedies reviewed here were created to achieve results like those of medicinal potassium citrate. Unlike potassium citrate, none of these remedies have ever been tried as stone preventions. The link takes you to trials showing that medicinal potassium citrate can prevent kidney stones. Instead these remedies rely on a reasonable logic: Potassium citrate prevents stones by raising urine citrate; equivalent amounts of alkali from a remedy that has no trial can increase urine citrate; therefore such a remedy should be able to prevent stones.
Put another way, there is no reason to doubt that an equivalent amount of alkali from one of these remedies will raise urine citrate to the same extent as an equal amount of alkali from potassium citrate itself. But given some contain two kinds of alkali, and given most contain more than potassium citrate, we cannot know if they are effective against stones.
CITRATE ALKALI IN THE NINE REMEDIES
Citric Acid vs. Citrate
An enormous service from Dallas was to measure how much citrate alkali a serving of each remedy provides. The amount of citric acid in a a serving gives no clue to the amount of alkali. If the product is very acid – has a low pH when dissolved in water or taken orally – most of the citric acid has its protons, and when metabolized produces no new alkali. If the product has a high pH, most of the citric acid lacks its protons (citric acid has three proton acceptor sites). It can only be metabolized with its protons, so metabolism takes up protons from the blood buffers, producing bicarbonate alkali. (I used a link to a sophisticated article that has a lot about alkali.) It is best to use the term citric acid (has its proton) and citrate (lacks its proton, produces alkali when metabolized) to distinguish the two.
In passing, I remind you that citrate is at the center of an ancient energy producing pathway. When we eat it, our cells are prone to use it in that pathway. As they do, the citric acid produces energy but not alkali. The citrate produces alkali and energy.
Below I focus on citrate alkali. Some products also contain alkali as bicarbonate.
Citrate Alkali and Price In the Nine Products
The products differ over an 8 fold range in the amount of citrate alkali per serving (left panel of the figure). KSP, LB, MSP, and NOWPC all have in each serving as much or more alkali as standard medicinal potassium citrate tablets (Dashed horizontal line is at 10 mEq of citrate alkali, the amount in a standard medicinal tablet). This might matter to patients as a convenience.
The right panel shows the cost in dollars of 10 mEq of citrate alkali from each product – how much each costs to give the citrate alkali in a single potassium citrate tablet. NOWPC is noticeable for a very low price as are HORPC and KCOP. Because the latter two do not have so much alkali in a serving they require one swallow more servings. NOWPC, however has an excellent price and each serving has just over 10 mEq of alkali. MSP and LLC are more expensive.
How to choose is not something I need to discuss. Remember, alkali is alkali, and cost per 10 mEq dose of alkali allows direct price comparisons. So shoppers can make decisions without further medical input. Matters such as flavor, or color, for example, may make a more expensive product desirable – or not. My main point is that nothing about any of the products has any relationship to stone prevention – so far as we know – except alkali, to raise urine citrate.
ADVERTISED VS ACTUAL ALKALI
The main paper I have reviewed here, from Dallas, notes some considerable discrepancies between the advertised and actual amounts of citrate in these products. An excellent review provides considerable additional material as a check against how the Dallas group interpreted product contents. This is important because product content is not so simple to find. I shall refer to the review as ‘this’ article, and ‘Dallas’ for the main one here.
Modest Discrepancies are Common
NOW® Potassium Citrate is listed in this article as containing only potassium citrate – 5 mEq in 1/4 teaspoon of the product. But the Dallas group measured 12.5 mEq of citrate in 1/4 teaspoon and given the high pH about 12 mEq of citrate alkali. Presumably this is a problem with what the vendor provides as information.
Litholyte®, I presume the powder, is listed as containing per packet 6.5 mEq of citrate and 3.5 mEq of sodium bicarbonate. The Dallas group indeed found about 7 mEq of citrate alkali and about 70 mg (3 mEq) of sodium, presumably all bicarbonate. So this product seems consistent between measurement and product information.
TheraLith XR®, presumably per tablet is listed as 2.1 mEq of citrate (1.2 as Mg, 0.9 as K); Direct measurement for 2 tablets was 7 mEq of citrate, and given the high pH about the same citrate alkali. As for NOW® the discrepancy (4.2 vs 7 mEq) is not explained.
Kidney COP®, is listed at 4.5 mEq citric acid + 0.6 mEq Mg citrate or 5.1 of potential citrate alkali. That is indeed what was found – 5.4 mEq but given the low pH only 3.5 mEq is citrate alkali.
KSP tabsTM, 2 mEq of citrate (0.9 Mg, 1 as K) and 2 mEq of sodium bicarbonate giving 4 mEq of alkali in a tablet. Directly measured citrate was 26 mEq of which about 14 mEq was citrate. Measured sodium in one effervescent tablet was 224 mg (9.7 mEq). I suspect this is because of a difference on counting. The measurements in one tab seem about 2 times the advertised content for sodium. For citrate the discrepancy is so large one cannot explain it.
LithoBalanceTM, citrate of 4.4 mEq in one scoop (0.6 as Mg); direct measurement gave 28 and 39 mEq of citric acid providing 9.7 and 13.9 mEq of citrate alkali in a scoop.
Moonstone® Powder. It was not in this article. With more difficulty than I should have encountered I found a label showing/4 capsules: Mg 210 mg (8.75 mmol x 2 = 17.5 mEq); 140 mg (6.1 mEq) sodium; 280 mg K (7.18 mEq); 30 mEq of citrate as these three salts. The Dallas group studied 1 package (26 gm) of the powder and found 60 mEq of alkali advertised. Indeed this much citric acid was found but given the low pH the actual content was only 16 mEq.
These Products are Lightly Regulated
Nothing about the preceding is to impugn the products. They are commercial products more like lima beans or tomato soup than actual medications used against disease. Perhaps they even less regulated than lima beans or tomato soup. That, too, is not a criticism. Government decides how to regulate and views these kinds of supplements as benign enough to regulate lightly. The seeming variability poses no direct risk except that one may not get from the product what is advertised on the label.
The best defense is to test. If your physician requests you take one of these remedies, presumably to raise urine citrate or pH, be sure and retest to see if citrate or pH has risen. The products are not held to the standards of prescribed medication, so be sure it works for you.
WHAT ELSE EACH PRODUCT CONTAINS
To varying extents each may contain considerable sodium, calcium, or magnesium. The Dallas group conveniently provides measurements standardized to 10 mEq of citrate – how much sodium, calcium, magnesium, or potassium you get from the equivalent of one 10 mEq potassium citrate tablet.
KSP and LLP contain 150 and 100 mg of sodium for each 10 mEq of alkali. If one takes a common dose equivalent to four 10 mEq potassium tablets a day, KSP will provide an additional 4 x 150 = about 600 mg of sodium (my figures here are approximate and rounded for simplicity).
That is a lot considering that the US tolerable upper limit for sodium is about 2300 mg, and 1500 mg is considered, by many authorities, as ideal. LLP will provide about 400 mg for the same daily dose of 40 mEq citrate (equivalent to four 10 mEq potassium citrate pills).
KCOP contains almost 150 mg of calcium in a dose that delivers 10 mEq of citrate. So if you use it at the common dose of 40 mEq alkali a day (four 10 mEq potassium citrate tablets) you get just about 600 mg of calcium. The ideal daily intake of calcium is about 1000 to 1200 mg, meaning this remedy provides nearly 1/2 of a very liberal daily intake.
Is that a problem? In way it might be. We need real foods, including dairy products, whereas this remedy is essentially a hefty calcium supplement. Given that calcium is most important for bone, and the main study I know of concerning calcium intake and bone mineral balance used supplements with meals, I would think KCOP should be used with meals. Typically people take potassium citrate 2 10 mEq tabs twice a day. Because they contain just that – potassium citrate, timing to meals is not necessary. If four KCOP doses are taken and food calcium is at US ideal levels, calcium intake can be very high (1200 + 600 = 1800 mg/d). That might be too high for some people. Those with even mild kidney impairment, for example, a not uncommon result of stone disease.
KCOP, TLY, MSP and LLC all have abundant magnesium. For KCOP, a conventional 40 mEq dose of citrate alkali (four potassium citrate tablets a day) will give over 800 mg of magnesium. Most magnesium is in cells, and I know of no special hazard from an additional 800 mg/d from pills. Present US daily intake recommendations for magnesium are around 400 mg, so the 800 mg added to food does raise one’s eyebrows. Corresponding values for TLY (600 mg/d), and MSP (500 mg) also seem high.
At their highest, none of these products provides appreciably more potassium than 40 mEq of standard potassium citrate would provide (40 mEq). Many have little potassium, so if one needs to replete potassium in a kidney stone patient they will not do. Stone patients not rarely are given thiazide diuretics, which cause potassium loss, and require significant replacement. This is often in the form of potassium citrate. Another common reason is diarrhea, a cause of stones in GI disease.
All Four At Once to Make it Easy to See
With a little magic and a little counting up, I got all the four together in one place. Each bar shows how much potassium, magnesium, calcium, and sodium are in each product. All are in mEq, meaning their actual comparable units of charge to balance citrate or bicarbonate. In general sodium will be with bicarbonate. The other three are usually with citrate. All are presented in amount/10 mEq of citrate alkali.
A few (HORPC, HOWPC) are almost all potassium citrate. KSP and LLP have notable sodium presumably as bicarbonate. KCOP is remarkable for its high calcium, and KCOP, LLC, MSP, and TLY for their magnesium. None of this is by way of criticism, merely to illustrate the variety of formulations. Magnesium may cause GI symptoms, and so may potassium.
WORK BY OTHER SCIENTISTS
Several groups have reported studies using these OTC alkali, and I would be an ecumenical reporter.
A crossover study – each subject gets each product – tested citrate response in 10 people to “LithoLyte (20 mEq 2 times per day) or KSPtabs (1 tablet 2 times per day).” The last would provide about 30 mEq of alkali – take a look at my first figure, left panel. For Litholyte, given about 7 mEq of alkali per serving this would have required about 3 – 4 servings twice a day. Litholyte did not raise urine citrate significantly, but KSPtabs did (758 vs 597, and 797 vs 597). Note these were 10 normal people, and patients with low urine citrate would show more dramatic results.
A structured interview study included useful analytical data on the total alkali available in a range of products which only slightly overlap those studied in Dallas.
Of interest, the total alkali in the KSP products and in LithoBalance are near to those of similar products from the same distributor. Stone Breaker stands out as having no alkali but presumably some other power to eradicate stones.
About the interviews, what brought people to an item, who used them, why, that is all outside what I have to say here. As well, outside my expertise, as I know nothing about opinion research.
WHO SHOULD USE THESE REMEDIES?
Patients Who May Benefit From Alkali Supplements
“These remedies” refers to all the products here, though my main interest is in those studied in Dallas. All are, if anything, alkali, and of use when alkali are of use. When alkali are not of use, they are not of use. Nothing about them has anything to do with kidney stone prevention – that is established by any science at all – apart from increase of urine citrate or pH via the imposition of an alkali load on the blood buffers.
Who Benefit From Alkali Supplements?
Stone Formers with Low Urine Citrate
Certainly not all stone formers. We do not prescribe potassium citrate just because someone has formed calcium stones. For example more is not sensible in calcium stone formers who have very high urine citrate. Some stone formers have very high urine pH and form calcium phosphate stones. Extra alkali in such people has has never been tested for stone prevention, and to me at least has some risk of worsening things.
The best data relating risk of new stone onset to urine citrate came from the Curhan group at Harvard. They found risk increased as urine citrate fell below 400 mg/d. Therefore I accept that number as a not unreasonable basis for one of these remedies, or for potassium citrate tablets themselves.
Those with Other Specific Conditions
Alkali supplements have their place to prevent uric acid stones. Extra alkali may benefit bone disease. Alkali supplements are needed for some GI diseases with diarrhea and alkali loss. Ileostomy is a clear example, but often requires sodium alkali. Some experts recommend alkali supplements for chronic kidney disease. Alkali raise urine pH and that can help reduce cystine supersaturation in cystinuria. Alkali are always used to treat the metabolic acidosis of distal renal tubular acidosis. But these are medical conditions with real medical decisions that need making, and need for real medical supervision. It is the physician who chooses alkali, the proper dose, and perhaps one of these supplements.
The Special Case of Uric Acid Stones
Curiously, ads for these products are not aimed at uric acid stone formers. Alkali can prevent such stones to absolute, and even dissolve them, from time to time. This because it is low urine pH that causes them, and alkali can raise urine pH. Of course, routine potassium citrate tablets will do the same.
Uric acid stone formers would be ill advised to use these remedies on their own. Label citrate content does not gauge citrate alkali. Repeated testing is required to be sure urine pH rises and remains high – these products are not regulated like drugs and composition is not guaranteed in the same manner. Patients need their physicians to adjust dosage in accord with actual alkali content as presented in the Dallas report and to monitor 24 hour urine pH. With such supervision, any of the products should work well.
PEOPLE IN GENERAL WILL NOT BENEFIT
To say that one should buy and take any of these products just because one has formed a kidney stone – that is as unacceptable as it is to prescribe potassium citrate itself for the same ‘just because’ reasons. Alkali are not a general nostrum, not some invariable benefit to kidneys, or to the body.
For the common person without evident disease, alkali supplements are not in any way known to improve health – kidney health, bone health, or any other kind. I might say, though it is not the topic here, that the vast richness, beauty, and appeal of fruits and veggies includes such an abundance of alkali, mainly as potassium, that they alone can provide 60 to 100 mEq daily along with pleasure, too. I wonder, sometimes, why people might want to choose supplements for that which fills their grocery stores and graces the tables of those who gather it into their kitchens and prepare it into divine sustenance.
What I mean by all this high talk is that fruits and veggies provide such ample alkali healthy people never need pill supplements. The US diet guidelines call for ample fruits and veggies for everyone, every day. Let’s do that and leave pills for those with diseases that somehow force them upon us.
I WILL NOT RECOMMEND THE ‘IDEAL’ CHOICE
Because these are commercial products, like tomato soup, or green beans, that compete on price and other qualities for consumer dollars, and because this site abjures connection to commerce I leave purchesers to their own judgement.
But I, for stone formers, have about the entire product group a potent and general prejudice.
It is your physician who should point you to a product, if that is medically proper. If it is clear from your physician that alkali are suitable as a treatment, and your physician has recommended some amount of alkali, one can safely use these products and benefit from them provided dosing is adjusted for how much alkali each contains in a serving, and provided the extra sodium, calcium, and magnesium are not a concern for the physician who is responsible for your care. Though they may reside on OTC shelving, these products should be used with the guidance of physicians. For it is upon them that society, law, and custom have placed the robe, the seal, and the yoke of authority.