Plant-based running — DIAAS protein, B12, algae EPA/DHA
Plant-based diets support elite running, with three non-negotiable caveats. Here is the PhD-level playbook for the vegan marathoner.
Barr & Rideout (Nutrition, 2004) and subsequent reviews (Craddock et al., Nutrients, 2021; Rogerson, JISSN, 2017) confirm no performance decrement in plant-based runners when macronutrient and micronutrient needs are met. Scott Jurek (7× Western States winner), Rich Roll, Fiona Oakes, and Meb Keflezighi (post-career) demonstrate the ceiling. But "when needs are met" is doing a lot of heavy lifting in that sentence. Three caveats matter.
Protein per meal must rise. Plant proteins generally have lower digestibility and lower leucine content. The Digestible Indispensable Amino Acid Score (DIAAS) framework: whey DIAAS >1.0, soy ~0.9, pea ~0.7, wheat ~0.4. Practical implications: plant-based runners should target 30–40 g of protein per meal (versus 20–25 g for omnivores), combine complementary sources (rice + pea, legume + grain), and consider a plant-based protein supplement post-workout. Pea + rice blends approach whey's amino-acid profile at roughly 2:1 pea:rice ratio.
B12 is non-negotiable. No bioavailable plant sources exist. 250–1,000 µg/day of cyanocobalamin or methylcobalamin, or 2,500 µg weekly, is mandatory for vegans. Deficiency causes macrocytic anaemia, peripheral neuropathy, and cognitive decline — common in long-term vegan athletes who neglect supplementation.
Omega-3 is the quiet deficiency. ALA → EPA conversion is ~5–10%; ALA → DHA is <1% (especially in men). Flax, chia, walnuts provide ALA but are inadequate as the sole omega-3 source. Algae-based EPA/DHA, 250–500 mg/day, is the evidence-based solution for plant-based runners.
Iron strategy is more complex. Non-heme iron (all plant iron) is absorbed at 2–20% depending on context, versus 15–35% for heme iron. Enhancers: vitamin C (can triple absorption), beta-carotene, lactic-acid fermentation. Inhibitors: phytates (legumes, grains), tannins (tea, coffee), calcium, oxalates (spinach). Soaking, sprouting, and fermenting grains and legumes reduces phytate. Practical: vitamin-C food at every iron-containing meal; separate tea/coffee from iron meals by 1+ hour.
Calcium, vitamin D, zinc, iodine warrant attention. Fortified plant milks, dark leafy greens (kale > spinach due to lower oxalate), tahini, and calcium-set tofu cover calcium. Vitamin D supplementation 1,000–2,000 IU/day. Iodine from iodised salt or moderate sea vegetable. Zinc from pumpkin seeds, legumes, whole grains.
Carbohydrate is rarely the problem. Plant-based diets are naturally carb-rich. A runner eating legumes, rice, oats, sweet potato, and fruit is already in 6–8 g/kg territory without trying. The challenge is rarely "enough carbs" and almost always "enough protein per meal, the right fats, iron, B12".
The Kenyan elite diet (Onywera et al., IJSNEM, 2004) is essentially plant-based: ~76% carbohydrate, 10% protein, 13% fat — ugali, githeri, rice, chapati, sukuma wiki (collard greens), milk, small amounts of meat. Nothing exotic. The lesson: simple, consistent, whole-food-based, carb-adequate eating works.