Nutrient Coverage on a Plant-Based Diet

The nutrients that need deliberate planning (B12, iodine, calcium, vitamin D, omega-3, protein, iron, zinc, selenium), general adult reference values, and how to check coverage.

A well-planned plant-based diet can meet adult needs, says the Academy of Nutrition and Dietetics (Melina et al., 2016). "Well-planned" is doing the work. The NHS names nutrients a poorly planned vegan diet can miss: calcium, iron, B12, iodine and selenium. This page is education, not medical advice. Its figures are reference values for healthy adults, not treatment doses.

The principle: coverage before ranking

Check that a typical week covers the essentials before comparing foods by how impressive they sound. A ranked list of "superfoods" can look excellent and still leave out B12 or iodine; How to Rank Foods Honestly explains why. Network monitoring has the same trap, by analogy: the all-green dashboard in Evidence-Based Troubleshooting. Three healthy hosts say nothing about the two the dashboard never polled. Both checks start from the full expected list.

The method makes three assumptions:

Reference values describe groups. The RDA covers nearly all healthy people (97 to 98 percent), so most need less.
Labels and databases estimate intake. They do not measure what a body holds.
A gap on paper is a planning question, not a diagnosis.

Do not stack duplicate supplements: a multivitamin, a fortified milk and a tablet may carry the same nutrient, and several here have upper limits. Protein is a coverage item too; see Protein for Muscle on a Plant-Based Diet. Meals are built in Plant-Based Eating Framework, categories checked in Daily Dozen and Food Roles.

Reference values at a glance

Adult figures from the NIH Office of Dietary Supplements. RDA means a level meeting the needs of nearly all healthy people; AI means an adequate intake where evidence is thinner; UL is an upper limit.

Vitamin B12. Adult reference: RDA 2.4 mcg. Note: Absorption falls at high single doses.
Calcium. Adult reference: RDA 1,000 mg (19 to 50; men to 70); 1,200 mg for women 51+ and men 71+. Note: .
Iodine. Adult reference: RDA 150 mcg. Note: UL 1,100 mcg.
Vitamin D. Adult reference: RDA 600 IU (15 mcg), ages 19 to 70. Note: UL 4,000 IU.
ALA (omega-3). Adult reference: AI 1.6 g men, 1.1 g women. Note: No recommendation set for EPA or DHA.
Iron. Adult reference: RDA 8 mg men, 18 mg women 19 to 50. Note: Vegetarians need about 1.8 times as much: plant (non-heme) iron is absorbed less well.
Zinc. Adult reference: RDA 11 mg men, 8 mg women. Note: Phytate lowers absorption.
Selenium. Adult reference: RDA 55 mcg. Note: UL 400 mcg.
Choline. Adult reference: AI 550 mg men, 425 mg women. Note: .

Established: the published values. Provisional: how they apply to one person, which depends on absorption, health and medication.

Nutrient by nutrient

B12

NIH is blunt: plant foods do not naturally contain B12. Fortified cereals and nutritional yeasts do, but brands differ: about a quarter cup of fortified yeast gives 8.3 to 24 mcg. So a fortified food counts only if the label states the amount and you eat it often enough. Absorption is about half at doses under 1 to 2 mcg, and about 2 percent at 500 mcg. So how often you take it matters, not only the dose.

What counts as "reliable" is still argued. The Academy of Nutrition and Dietetics gives fortified foods or supplements as examples of reliable sources. Fumio Watanabe's group (Nutrients, 2014) agree on spirulina-type products: they carry mostly pseudovitamin B12, inactive in humans. Yet they call nori the most suitable plant source, about 4 g meeting the RDA. Their own figures for purple laver run from about 32 to 134 mcg per 100 g. A source that varies fourfold is hard to plan around. Ask a clinician or dietitian to choose one regimen rather than combining several.

Calcium

Low-oxalate greens such as kale, bok choy and broccoli give up their calcium about as well as milk (NIH). Spinach and chard are high in oxalate (Avila-Nava et al., 2021), which binds calcium. NIH puts absorption from spinach at 5 percent, against 27 percent for milk; for chard it is inferred. Calcium-set tofu (253 mg per half cup) and fortified soy milk (299 mg per cup) are the practical anchors. Add up the labels over a day.

Iodine

NIH lists a quarter teaspoon of iodised salt at 78 mcg, roughly half the 150 mcg RDA. FDA equates the Dietary Guidelines' sodium limit, under 2,300 mg a day, with about one teaspoon of salt. So that quarter teaspoon spends a quarter of the limit, roughly 575 mg. Do not raise salt just to hit iodine. Whether a salt is iodised varies by product; sea salt usually is not. Seaweed ranges from 16 to 2,984 mcg of iodine per gram. People with thyroid disease need individual advice.

Vitamin D

Sunshine is not a quantified plan. NIH lists season, time of day, cloud cover, skin melanin and sunscreen as factors. Fortified soy, almond and oat milks give about 100 to 144 IU a cup. Know the gap between the RDA and the UL, and check existing products before adding more.

Omega-3

ALA, from flax, chia, walnuts and canola oil, is the only essential omega-3 (NIH). The body converts under 15 percent of it to EPA and DHA. Fish get those from microalgae, hence algae oils. The Institute of Medicine set no intake recommendation for EPA or DHA, so whether vegans need a direct source is open. Check a product's EPA and DHA amounts, not just "algae oil".

Iron, zinc, selenium and choline

Legumes, tofu, whole grains and seeds supply iron and zinc. Vitamin-C-rich produce such as peppers or citrus, eaten with legumes, improves non-heme iron absorption. Do not take iron without assessment: some people absorb too much (hereditary haemochromatosis), and high doses upset the gut. Zinc absorption runs from 5 to over 50 percent, depending on phytate; NIH notes that soaking beans, grains and seeds may help. Brazil nuts average 544 mcg of selenium per ounce in USDA data, above the 400 mcg UL, and vary widely. A daily handful is not a precision tool. Choline comes from soybeans, kidney beans, potatoes and broccoli.

Auditing a representative week

Write down a typical week, not an ideal one.
Pull out the actual labels of milk, tofu, yogurt and any supplements.
Total calcium, B12, iodine and vitamin D from food and supplements against the table.
Note gaps and fix the cheapest repeatable one first.

A food log estimates intake; it cannot diagnose status. Blood tests and symptoms are for a clinician. The audit serves judgment: it shows which question to take to that clinician, and which staple to buy. Staples are in Kitchen Staples and Food Safety; weighing claims is in Reading Nutrition Evidence; the wing's overview is Health and Nutrition Orientation.

Safety overrides

General figures yield to individual facts.

Food allergies come first.
Fava beans can trigger red blood cell destruction in G6PD deficiency (MedlinePlus).
On warfarin, keep vitamin K intake steady; sudden changes can strengthen or weaken the drug (NIH).
Grapefruit can change how some medicines work; FDA requires warnings on some drug labels.
Dry kidney beans must be boiled properly; see Kitchen Staples and Food Safety.

Where this could be wrong

Strongest objection. The RDA covers 97 to 98 percent of people, so a week below it may be no deficit. Labels also miss absorption. An audit can flag gaps that are not there and miss ones that are.

Best reply. The audit claims less. It finds where a week relies on luck, such as no counted B12 source. That is a planning gap whatever one person's need turns out to be.

What would settle it. Studies comparing audited intake with measured status, such as blood B12 markers, in the same people. This page has not checked for them, so the question stays open.

Try this

Open one NIH fact sheet from the table. Copy its RDA, UL and one food row, then check them against this page.
From this week's real labels, total each day's B12 in micrograms. Write each total beside 2.4 and count the days with none.
List every supplement and fortified food in the cupboard. Mark each nutrient that appears on two or more labels.