B vitamins are water-soluble, which means they are filtered by the kidneys and lost more easily during dialysis. They also play a role in homocysteine metabolism — a marker linked, though not conclusively, to cardiovascular risk in CKD.

What the NHS says about B vitamins

For most UK adults with healthy kidneys, a varied diet that follows the Eatwell Guide provides enough B vitamins, with two notable exceptions:

  • Folic acid: women planning pregnancy or in the first 12 weeks of pregnancy should take 400 µg daily.
  • Vitamin B12: people on a strict vegan diet or with pernicious anaemia need a supplement or fortified foods.

B vitamins in CKD

People on dialysis often lose water-soluble vitamins through the dialysate, and renal-specific multivitamins (such as Renavit) are commonly prescribed in the UK. They contain B1, B2, B6, B12, folic acid, niacin, biotin, pantothenic acid and vitamin C in renal-appropriate doses.

For people with non-dialysis CKD, large doses of B vitamins are not routinely recommended. A high-quality 2010 trial published in JAMA found that high-dose folic acid, B6 and B12 in CKD did not reduce vascular events — and may even have increased risk of decline in kidney function.

Practical takeaways

  • Eat wholegrains, pulses, eggs, dairy and lean meat for natural B vitamins.
  • If you are on dialysis, take any renal multivitamin your team has prescribed.
  • Avoid mega-dose B-complex products bought online unless your renal team has explicitly recommended them.