1Division of Nephrology, Fondazione Policlinico Universitario A. Gemelli, Catholic College of the Sacred Coronary heart, Rome, Italy
2Channing Division of Community Medication, Division of Medication, Brigham and Ladies’s Hospital, Harvard Medical College, Boston, USA
3Division of Nephrology and Transplantation, Maine Medical Heart, Portland, USA
1Division of Nephrology, Fondazione Policlinico Universitario A. Gemelli, Catholic College of the Sacred Coronary heart, Rome, Italy
2Channing Division of Community Medication, Division of Medication, Brigham and Ladies’s Hospital, Harvard Medical College, Boston, USA
4Renal Division, Division of Medication, Brigham and Ladies’s Hospital, Harvard Medical College, Boston, USA
Summary
Introduction
Vitamin B6 (pyridoxine) consumption may decrease the urinary excretion of oxalate, which in flip is among the main determinants of calcium oxalate kidney stones.(1) The transamination of glyoxylate to glycine requires vitamin B6 as a cofactor of the enzyme alanine-glyoxylate aminotransferase and a deficiency of vitamin B6 may improve the quantity of glyoxylate reworked into oxalate by the lactate dehydrogenase. It has been reported that vitamin B6 deficiency ends in elevated manufacturing and excretion of oxalate,(2) and supplementation of vitamin B6 has been proven to cut back urinary excretion of oxalate in some research(3–7) however not in others.(8,9) Earlier cohort research investigating the affiliation between consumption of vitamin B6 and incident kidney stones discovered conflicting outcomes, with no affiliation amongst males collaborating within the Well being Professionals Observe-up Research (HPFS)(10) and an inverse affiliation amongst older females within the Nurses’ Well being Research (NHS) I.(11) We sought to research the affiliation between consumption of vitamin B6 and incident kidney stones in the identical cohorts after further follow-up time, in addition to in a further cohort of youthful females within the NHS II during which the affiliation was not investigated earlier than.
Strategies
Outcomes
A complete of 193,676 members have been included within the evaluation of incident kidney stones (42,919 from HPFS, 60,128 from NHS I and 90,629 from NHS II). Baseline traits of the examine members within the lowest and highest classes of vitamin B6 consumption are proven in Desk 1. The quantity of calcium from dietary supplements and whole intakes of potassium, oxalate, magnesium and whole vitamin C tended to be greater within the highest in contrast with the bottom classes of vitamin B6 in all cohorts. Total, 6,308 incident kidney stones have been confirmed throughout 3,108,264 person-years of follow-up.
Estimates of affiliation between classes of vitamin B6 and incident stones are reported in Desk 2. In univariate analyses, there was no affiliation between consumption of vitamin B6 and incident stones. The HR for stones within the highest class in contrast with the bottom was 0.92 (95% CI 0.77, 1.10; p-value for pattern = 0.81) for HPFS, 0.84 (95% CI 0.69, 1.02; p-value for pattern = 0.16) for NHS I, and 0.93 (95% CI 0.81, 1.07; p-value for pattern = 0.79) for NHS II. After multivariate adjustment, the outcomes didn’t change considerably: the HR for stones within the highest class in contrast with the bottom was 1.05 (95% CI 0.85, 1.30; p-value for pattern = 0.61) for HPFS, 0.95 (95% CI 0.76, 1.18; p-value for pattern = 0.42) for NHS I, and 1.06 (95% CI 0.91, 1.24; p-value for pattern = 0.34) for NHS II. The pooled adjusted HR for the very best class in contrast with the bottom was 1.03 (95% CI 0.92, 1.15; p-value for pattern = 0.60). After finer stratification into 9 classes of consumption, the outcomes didn’t change considerably (pooled adjusted p-value for pattern = 0.87).
There was no vital impact modification by age, BMI or dietary oxalate consumption.
Dialogue – “b vitamins kidney stones”
Vitamin B6 is a water-soluble vitamin whose advisable day by day allowance is 1.3 mg for women and men 19 to 50 years, 1.7 mg for males ≥50 years and 1.5 mg for females ≥50 years.(18) The standard quantity of vitamin B6 in multivitamins is 1.5–5.0 mg. Vitamin B6 may scale back oxalate excretion by lowering its manufacturing within the liver. Actually, it’s a cofactor of the alanine-glyoxylate aminotransferase, which metabolizes glyoxylate into glycine. When this metabolic pathway is proscribed by inadequate ranges of pyridoxine, extra glyoxylate can be obtainable for conversion into oxalate by the lactate dehydrogenase. Regardless that a dose-response relationship between vitamin B6 and urine oxalate can be anticipated given the purported mechanism of motion, earlier research didn’t constantly report such a dose-response relationship.
In our longitudinal potential examine, we discovered no affiliation between consumption of vitamin B6 and danger of kidney stones even amongst people with excessive vitamin B6 consumption. Though to the most effective of our information no randomized managed research can be found on the impact of vitamin B6 on the chance of kidney stones, some research have beforehand reported a useful impact of vitamin B6 in lowering urinary excretion of oxalate, a significant determinant of calcium oxalate stone danger. As an example, Balcke and colleagues confirmed that administration of vitamin B6 in 12 sufferers with calcium oxalate calculi resulted in a 30% discount in urine oxalate.(3) Equally, Mitwalli et al. reported a major discount in urine oxalate after administration of 250–500 mg of vitamin B6 in 12 sufferers with calcium oxalate calculi and hyperoxaluria.(5) A retrospective evaluation of 95 stone formers with idiopatic hyperoxaluria confirmed that administration of as much as 200 mg/day of vitamin B6 resulted in a 30% discount of urine oxalate (from 58 to 41 mg/24h), with normalization of hyperoxaluria in 39% of sufferers.(7) Nonetheless, different research failed to indicate a useful impact of vitamin B6 supplementation: in a examine carried out on 7 sufferers with idiopathic hyperoxaluria and 10 wholesome controls, administration of 200 mg/day of pyridoxine had no impact on urine oxalate among the many former, and resulted in a paradoxical improve in urine oxalate among the many latter.(8) Extra just lately, a relatively bigger examine analyzed the impact of a 7-day course of vitamin B6 at a dose of 300 mg/day on urinary excretion of oxalate amongst 55 idiopathic calcium stone formers (40 with and 15 with out hyperoxaluria) and 50 wholesome topics: urine oxalate didn’t change considerably in any group.(9) Within the HPFS and NHS cohorts, consumption of whole vitamin B6 was not related to urinary oxalate excretion.(19)
Our examine confirms the earlier findings of a scarcity of affiliation between consumption of vitamin B6 and danger of stones amongst males;(10) we didn’t verify the earlier inverse affiliation amongst older females.(11) The rationale for such discrepancy could be the elevated energy of the present examine as a consequence of an extended follow-up time and bigger variety of incident occasions.
The strengths of our examine embody the evaluation of knowledge from three giant, ongoing and nicely characterised cohorts with lengthy follow-up time and validated and up to date data on different vitamins and comorbidities. Our examine additionally has limitations, together with the truth that nearly all of the members have been white and the shortage of stone and urine composition knowledge for all of the members; moreover, the doses of vitamin B6 consumed by members even within the highest classes have been decrease than these used within the earlier interventional research cited. Lastly, our examine doesn’t exclude the likelihood that vitamin B6 could also be related to decrease danger in chosen people. For instance, some sufferers with kind 1 major hyperoxaluria would profit from excessive dose vitamin B6 supplementation.(20,21)
In conclusion, consumption of vitamin B6 shouldn’t be related to danger of incident kidney stones.
Acknowledgments
Abbreviations