I am the lucky recipient of a Jesuit high school education in San Francisco. Fathers Becker/Clemo/Pallas/etc. taught me to think laterally and always try to find the root cause of an issue. This ideology is probably what led me into naturopathic medicine originally, but I digress. Father Becker especially taught me that seeking an answer to a vexing problem may also require learning to ask entirely new questions. He also made the point that you may have to see with new eyes or alter your view of the world a tad if you wish to actually understand what the answers to your new questions provide you.

An example of this was my article on gel capsules several months ago. When I realized some people are taking 20 – 40 capsules/day, my interest was piqued to discover if there was a clear-cut answer as to any health issues associated with consuming so many unnaturally “natural” substances. Unfortunately, there wasn’t but I still empty my cap contents into a cup with my other powders every morning because it just feels right.

Today my mind stumbled onto another possible issue and the title of today’s column: B vitamin urine. For some reason everyone, including those of us with exceptionally clean and diverse diets, require massive amounts of encapsulated B vitamins, sometimes hundreds of times the RDA. You take these exceptional amounts of B vitamins and, like magic, a strange yellow color to your urine appears. This occurs because urinary water-soluble vitamin levels reflect their relative dietary intakes and are suitable biomarkers for measuring those intakes, although vitamin B12 is an exception.¹

Since B vitamins are water-soluble and are excreted through the urine, everyone thinks that they are harmless. Here is an example of the capsular contents of a typical B vitamin supplement:

• B1 100 mg 8,333% of the Daily Value (DV)
• B2 12.7 mg 977% DV
• B3 108 mg 675% DV
• B6 16.7 mg 982% DV
• Folate 1007 mcg 167% DV
• B12 400 mcg 16,667% DV
• Biotin 400 mcg 1,333% DV
• B5 100 mg 2,000% DV

No wonder our urine turns yellow! Maybe we shouldn’t eat at all and just consume B vitamin capsules.

B vitamin urine should come as no surprise to anyone who has taken physiology or taught physiology, both of which I am guilty of. Basically, your kidneys filter on average 180 liters of blood/day or almost a 50-gallon drum. They accomplish this Herculean task rain or shine or snow, 24/7, and whether we ask them to or not. These large amounts of B vitamins are altering the color of our urine because they are floating around overabundantly in the plasma from excessive supplementation, which forces the kidneys to perform their main function: homeostatic control of blood plasma components. The kidneys then don’t reabsorb the excess amount of B vitamins in the plasma and let them slide into the urine and eventually into the nearest urine receptacle. Now, my question today is: by taking such massive doses of B vitamins, are we unduly taxing our kidneys and ushering them into a non-functional form at a faster rate than if we didn’t consume those enormous doses? Hopefully, I’ll be able to answer this question, as I love my kidneys (as everyone should) and want them to work effectively for as long as possible.

First off, why do B’s lead to this discernible yellow color of our urine? Most B-complex vitamins contain riboflavin or B2 which contains flavins or naturally occurring yellow pigments (For you Latin scholars, flavus means yellow).² As the kidneys filter out the excess B’s, our urine will return to its normal straw yellow color once this housecleaning task is accomplished. Also, most B’s are considered supposedly harmless, even when consumed in above dietary doses. The two exceptions are B6 and niacin, which can cause toxicity in moderate to large doses. For niacin, flushing is the major side effect. In addition, one may experience nausea, abdominal pain, dizziness, and liver damage. B6 in overzealous consumption primarily produces a peripheral neuropathy but also can initiate nausea and hypersensitivity to sunlight.²

Secondly, are there any studies demonstrating damage to the kidneys from B vitamins? One study from JAMA in 2010 was attempting to establish whether high doses of three B vitamins (folic acid, B12, B6) could lower hyperhomocysteinuria and improve diabetic nephropathy. Eligible participants had type 1 or 2 diabetes and a clinical diagnosis of diabetic nephropathy, with at least 300 mg/day of urinary albumin excretion or ≥500 mg/day of proteinuria. Participants were either given placebo or 2.5 mg/day of folic acid, 25 mg/day of B6, and 1 mg/day of B12. At the end of the study high doses of these three B vitamins resulted in a greater decrease in glomerular filtration rate/GFR and oddly enough also an increase in vascular events in the B vitamin group than in the control group. Granted this is only three B’s, but a lower GFR usually indicates some sort of renal deterioration.³

After scouring PubMed and various search engines, I could find no studies showing connections between low to moderate doses of vitamin B supplements and kidney damage. Almost every source said side effects of B’s are not common unless consumed in very large amounts where the overdose could be signaled by dizziness, frequent urination, constipation, diarrhea, abdominal pain, nausea, vomiting, and/or redness of the skin and itching. Although extremely rare, a person could develop an allergic reaction and experience itching, a rash, swelling, wheezing, or hives. People can also develop side effects to individual B complex components, but none of them list damage to the kidneys as a side effect.⁴

So, what is a poor health care practitioner or Joe/Jane Q. Public to think? When I was teaching physiology, I always attempted to teach my refractory 18-22-year-olds that they needed to decide how healthy they wanted to be in the distant future and to take care of their bodies accordingly in the present. That way they might reach an older age and still be functional physically. My best example was the simple difference between heart rates of 60 and 70 beats/minute. Here is a list:

1 day 60 bpm around 86,000 beats 70 bpm around 101,000 beats

1 year 60 bpm around 31 million beats 70 bpm around 36 million beats

That is a 5 million difference in one year, which is a 150 million beat difference in 30 years, a 300 million difference in 60 years, etc.

Then I gave the example of identical twins who, until 18 years of age, wore the same clothes, ate the same food, received the same amount of parental love, etc. At 18, they went off to college. One twin started smoking cigarettes, not exercising, and being exposed to large amounts of stress. The other twin exercised daily, never smoked, and practiced Transcendental Meditation religiously. The second twin could conceivably have an average heart rate of 60 bpm and the other twin 70 bpm. Finally, given identical genetics but different lifestyles, I would ask my students whose heart is going to last longer?

I am going to pursue a similar train of thought here. If a person buys the train of thought that they need extremely large amounts of the various B vitamins and they daily consume a B capsule with the above values, are they slowly wearing their kidneys out? Unfortunately, I can’t give you a scientific answer but will share what I choose to do.

I have a couple of genetic methylation SNPs that make it harder for me to keep my methylation cycle continuously running in a perfect circle. To help foster a smoothly running cycle, I take a supplement where the recommended dose is three capsules/day, which contain riboflavin at 90 mg (6,923% DV), vitamin B6 at 45 mg (2,647% DV), 5 mg of a mixture of L-5-methyltetrahydrofolate and L-5-methyltetrahydrofolic acid (a mere 1,250% DV), and vitamin B12 at 3 grams (a whopping 125,000% DV). I started out with one capsule/day and sure enough bingo: riboflavin urine. I put on Father Becker’s thinking cap and started opening the capsule and taking just a little bit each day and made the capsule last six days. A win/win situation: no more riboflavin urine and a much-reduced supplement bill!

After reviewing this article before I submitted it, Alan McDaniel, MD, gave me a counter thought. He believes that simple and reliable tests to detect B-complex deficiency aren’t available yet. So, he gives his patients, whom he thinks require a B multi, a low-dose B vitamin for two reasons. First, to establish if their intestinal tracts are functional enough to indeed absorb the B’s which he will ascertain by the color of their urine. Secondly, if they are, then he will titrate the amount down over three doses per day to find a dose that minimally changes urine color. Thanks Alan, it’s always awesome to hear other people’s thoughts that go beyond my own.

To end, I don’t need double blind studies to necessarily guide my clinical decisions. My common sense always seems to take me wherever I need to go. My recommendation: love your kidneys, eat real food, and try to take as low of a dose of any supplement, especially B’s, as you can.

References

1. Shibata K, Hirose J, Fukuwatari T, Relationship Between Urinary Concentrations of Nine Water-Soluble Vitamins and Their Vitamin Intakes in Japanese Adult Males. Nutr Metab Insights. 2014; 7:61-75
2. Russell M. Medical Nutrition From Marz. Portland, OR; 2^nd Edition, Omni Press: 1997.
3. House AA, et al. Effect of B-Vitamin Therapy on Progression of Diabetic Nephropathy: A Randomized Controlled Trial. JAMA. 2010;303(16):1603-1609.
4. https://www.md-health.com/Vitamin-B-Complex-Side-Effects.html