Plant-Based Nutrition Basics

"Plant-based" is a spectrum, not a binary. Understanding the distinctions helps match nutritional strategies to the appropriate diet pattern:

Term	Animal foods excluded	Animal foods allowed
Vegan	All animal products (meat, dairy, eggs, honey)	None
Lacto-ovo vegetarian	Meat, poultry, fish	Dairy and eggs
Lacto-vegetarian	Meat, poultry, fish, eggs	Dairy only
Ovo-vegetarian	Meat, poultry, fish, dairy	Eggs only
Pescatarian	Meat and poultry	Fish, dairy, eggs
Flexitarian	Mostly plant-based	Occasional animal products

The Academy of Nutrition and Dietetics (2016 position statement) confirms that well-planned vegan and vegetarian diets are healthful, nutritionally adequate, and appropriate for all life stages. The key word is well-planned — the nutrients below require active management.

Six nutrients deserve special attention on plant-based diets because they are either absent from plants, present in poorly absorbed forms, or found in insufficient quantities in typical plant-food patterns.

Nutrient	Why it's at risk	Best plant sources	Absorption tip or supplement need
Vitamin B12	Not found in plants (algae amounts unreliable)	Fortified nutritional yeast, fortified plant milks	Supplement required for vegans: 250 mcg/day cyanocobalamin
Iron (non-heme)	Non-heme iron 2–5× less absorbed than heme iron	Lentils (3.3 mg/cup), tofu, pumpkin seeds, quinoa, fortified cereals	Pair with 50–100 mg vitamin C; avoid coffee/tea within 1 hour of meals
Omega-3 (DHA/EPA)	Plants only provide ALA; conversion to DHA/EPA is <10% efficient	Flaxseed, chia seeds, walnuts (ALA only)	Algae-derived DHA/EPA supplement: 250–500 mg/day
Zinc	Phytates in grains and legumes reduce absorption by 25–35%	Hemp seeds (10 mg/100g), pumpkin seeds (7.5 mg/100g), cashews, lentils	Soak/sprout legumes; eat with acidic foods to reduce phytates
Calcium	Dairy excluded; oxalate in some plants (spinach, beet greens) blocks absorption	Kale (150 mg/100g, high absorption), fortified plant milks (300 mg/cup), tahini, edamame	Aim for 1,000 mg; use low-oxalate greens (kale > spinach)
Vitamin D	Sun exposure limited; D3 from animals, D2 from plants is less bioavailable	UV-exposed mushrooms, fortified foods	Supplement 1,000–2,000 IU D3 (vegan form: lichen-derived) daily
Iodine	Dairy and seafood excluded; iodine in soil varies by region	Seaweed (variable, can be excessive), iodised salt	Use iodised salt; consider 150 mcg supplement

The old myth that plant proteins must be combined at every meal to form complete proteins has been disproved. The body maintains a free amino acid pool that allows complementary proteins consumed throughout the day to meet all EAA requirements.

That said, regular pairing of complementary sources is a practical strategy that ensures adequate intake without precise tracking. The key principle: legumes are high in lysine but low in methionine; grains are the opposite.

Complementary pair	Limiting amino acid covered	Example meals
Legumes + grains	Methionine (from grains) + lysine (from legumes)	Lentil soup + bread, rice + beans, hummus + pita
Legumes + seeds	Methionine (from seeds) + lysine (from legumes)	Edamame + hemp seeds, lentil salad + tahini
Legumes + nuts	Methionine (from nuts) + lysine (from legumes)	Chickpea curry + cashews, black bean dip + walnuts

Soy (tofu, tempeh, edamame) is unique: it is a complete plant protein that requires no pairing. Making soy a daily anchor for protein simplifies plant-based meal planning considerably.

Tip: Aim for 1.3–1.6 g of protein per kg of body weight on a plant-based diet — slightly above the 0.8 g/kg RDA — to account for the lower average digestibility of plant proteins.

A well-structured plant-based diet minimises the need for supplements, but a few are close to universal requirements for vegans specifically.

Supplement	Who needs it	Recommended dose	Form to use
Vitamin B12	All vegans; vegetarians if low dairy/egg intake	250 mcg/day or 1,000–2,000 mcg 2–3×/week	Cyanocobalamin (most stable)
Vitamin D3	Anyone with limited sun exposure (most people)	1,000–2,000 IU/day	Vegan D3 from lichen
Algae omega-3 (DHA/EPA)	Vegans and pescatarians avoiding oily fish	250–500 mg DHA+EPA/day	Microalgae-derived
Iodine	Vegans not using iodised salt regularly	150 mcg/day	Potassium iodide
Creatine	Vegans and vegetarians (muscle performance)	3–5 g/day (monohydrate)	Synthetic (vegan-friendly)

Creatine deserves special mention: vegans and vegetarians have 50–70% lower muscle creatine stores than omnivores (Harris et al.), which may affect high-intensity exercise performance. Supplementing is inexpensive, safe, and evidence-based.

Warning: Do not rely on nutritional yeast as your sole B12 source — B12 content varies widely by brand and is degraded by light. Only fortified nutritional yeast with stated B12 mcg per serving counts toward your intake.

Many people transition to a plant-based diet by removing animal foods without adequately replacing them — leading to nutrient gaps and a lower-quality diet overall. Awareness of these pitfalls prevents them.

• Pitfall 1: Relying on processed vegan foods. Plant-based burgers, vegan cheeses, and mock meats are often high in sodium (500–900 mg/serving), saturated fat (from coconut oil), and refined carbohydrates. Base meals on whole foods first.
• Pitfall 2: Insufficient protein. Replacing chicken with a side salad leaves a 25–30 g protein gap. Replace animal proteins 1-for-1 with legumes, tofu, or tempeh.
• Pitfall 3: Low calorie density awareness. Whole plant foods have lower calorie density — a vegan diet can easily be under-fuelling for active people without deliberate energy tracking.
• Pitfall 4: Ignoring B12 because you "eat healthy." No amount of dietary health consciousness produces B12 from plants — it is only made by bacteria, and the trace amounts in fermented foods and soil on vegetables are insufficient.

Pitfall	Quick fix
Low protein	Add 1 cup legumes or 150g tofu/tempeh per meal
Low iron	Squeeze lemon juice on lentil and bean dishes
Low calcium	Use fortified plant milk daily; eat kale regularly
Missing B12	Take a daily cyanocobalamin supplement — no exceptions