How do B complex vitamins impact kidney, bladder, and urethra health?

From the Guidelines

B complex vitamins play a crucial role in maintaining kidney, bladder, and urethra health by supporting metabolic processes, reducing homocysteine levels, and preventing kidney stone formation. The most recent and highest quality study, 1, published in 2022, found that B vitamins, particularly B6, B12, and folate, help maintain overall kidney function and reduce the risk of stroke by lowering homocysteine levels.

Key Findings:

• B vitamins, especially B6, may help prevent kidney stone formation by reducing urinary oxalate levels 1
• Adequate B12 levels support nerve function throughout the urinary tract 1
• B vitamins support the immune system and tissue repair mechanisms, helping maintain the bladder's protective lining 1
• The recommended daily intake varies by specific B vitamin, generally ranging from 1.3-2.4 mg for B6, 2.4 mcg for B12, and 400 mcg for folate through a balanced diet or supplements 1

Mechanisms:

• B vitamins support cellular energy production, reducing inflammation and maintaining healthy epithelial tissues throughout the urinary system 1
• They help reduce homocysteine levels, which can be harmful to kidney tissues when elevated 1
• B vitamins, particularly B6, may help prevent kidney stone formation by reducing urinary oxalate levels 1

Recommendations:

• B vitamins should complement, rather than replace, medical treatment for specific urinary conditions 1
• Patients with kidney, bladder, or urethral conditions should consult their healthcare provider to determine the best course of treatment and supplementation 1

From the Research

B Complex Vitamins and Kidney Health

• The intake of vitamins B6 and C has been studied in relation to the risk of kidney stone formation in women 2.
• High doses of vitamin B6 may decrease oxalate production, whereas vitamin C can be metabolized to oxalate.
• A high intake of vitamin B6 was inversely associated with the risk of stone formation, with a relative risk of 0.66 for women in the highest category of B6 intake compared to the lowest category.

B Complex Vitamins and Diabetic Kidney Disease

• Vitamin B and its derivatives have been studied as a potential treatment for diabetic kidney disease (DKD) 3.
• The results of the study showed that thiamine was beneficial for reducing albuminuria in a single study, but there was a lack of improvement in kidney function or blood pressure following the use of vitamin B preparations used alone or in combination.

B Complex Vitamins and Urinary Tract Infections

• Vitamin A supplementation has been shown to be effective in improving the clinical symptoms of urinary tract infections and reducing renal scarring in girls with acute pyelonephritis 4.
• The study found that vitamin A supplementation reduced the duration of fever, urinary frequency, and poor feeding in girls with acute pyelonephritis.

B Complex Vitamins and Bladder Cancer Risk

• The association between dietary B group vitamin intake and bladder cancer risk has been investigated in a pooled analysis of prospective cohort studies 5.
• The study found that moderate intake of vitamin B1 was associated with an increased bladder cancer risk, while high intake of vitamin B1 was associated with an increased risk in men.
• In women, high intake of all vitamins and vitamin combinations, except for the entire complex, showed an inverse association with bladder cancer risk.

B Complex Vitamins and Age-Related Differences

• The circulatory and urinary B-vitamin responses to multivitamin supplement ingestion have been compared between older and younger adults 6.
• The study found that older adults had a lower area under the curve of postprandial plasma pyridoxine and pyridoxal-5'phosphate forms of vitamin B6, but a greater increase in plasma thiamine, riboflavin, and pantothenic acid.