Editing Nutrition (section)

=== Water-Soluble Vitamins (B Complex and C) ===

Water-soluble vitamins are minimally stored and are excreted in urine, so deficiency appears relatively quickly and toxicity is less common (though pyridoxine and niacin do have toxic syndromes). They are heat labile and leach into cooking water, so steaming or microwaving preserves more than boiling.

{| class="wikitable"
! Vitamin !! Deficiency syndrome !! Notes and sources
|-
| B1 thiamine || Beriberi; Wernicke encephalopathy and Korsakoff syndrome || Chronic alcohol use is the classic risk. Give thiamine '''before or with''' glucose to avoid precipitating Wernicke encephalopathy. Pork, whole grains, legumes.
|-
| B2 riboflavin || Cheilosis, angular stomatitis, glossitis || Milk, eggs, enriched grains. Destroyed by light, hence opaque milk containers.
|-
| B3 niacin || Pellagra: dermatitis, diarrhea, dementia, and if untreated death || Meat, fish, peanuts. High-dose niacin lowers LDL but causes flushing; aspirin 30 minutes prior reduces flushing.
|-
| B6 pyridoxine || Peripheral neuropathy, seizures, sideroblastic anemia || Isoniazid depletes B6, so pyridoxine is co-prescribed. Excess B6 itself causes sensory neuropathy.
|-
| B9 folate || Megaloblastic anemia '''without''' neurologic deficits; neural tube defects in the fetus || Leafy greens, legumes, fortified grains, liver, citrus. Depleted by methotrexate, phenytoin, and alcohol.
|-
| B12 cobalamin || Megaloblastic anemia '''with''' neurologic deficits (paresthesias, ataxia, decreased proprioception) || Requires intrinsic factor from gastric parietal cells. Pernicious anemia, gastrectomy, ileal resection, and long-term proton pump inhibitor or metformin use cause deficiency. Animal foods only.
|-
| C ascorbic acid || Scurvy: bleeding gums, poor wound healing, petechiae, loose teeth || Enhances non-heme iron absorption. Citrus, strawberries, tomatoes, peppers, broccoli.
|}

'''Nursing application:''' Folate supplementation can correct the anemia of B12 deficiency while the neurologic damage silently progresses. Never treat a megaloblastic anemia with folate alone until B12 status is known.