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Vitamin D on plant-based diets: D2 vs D3, lichen-derived vegan D3, and supplementation

Most plant-based eaters need supplementation. Vegan D3 from lichen is now widely available.

By Sara Greenfield, MS, RD · Published · Last updated

Vitamin D status is a problem for most modern populations, plant-based or otherwise. Indoor lifestyles, sunscreen use, latitude, and skin pigmentation all affect cutaneous synthesis, and the dietary contribution to vitamin D status is small for most non-supplementing adults. Plant-based eaters lose two of the most common dietary vitamin D sources (fortified dairy and fatty fish) but gain access to fortified plant milks and lichen-derived vegan D3 supplements. The practical answer for most plant-based eaters is supplementation.

This piece covers the vitamin D forms (D2 vs D3, vegan D3 sources), the supplementation case, and the clinical assessment.

Vitamin D2 vs D3

Two forms of vitamin D are relevant to supplementation and food fortification:

  1. Vitamin D2 (ergocalciferol) is plant-derived, typically from UV-irradiated yeast or mushrooms. It is the form used in most prescription vitamin D supplements and in some fortified foods. D2 is unambiguously vegan.
  2. Vitamin D3 (cholecalciferol) is animal-derived in most commercial preparations, typically from sheep wool lanolin. D3 is the form most commonly used in over-the-counter supplements and the form synthesized in skin from UVB exposure. Most D3 is not vegan.

Lichen-derived vegan D3 has been commercially available for over a decade and is now the standard recommendation for plant-based eaters who want D3 specifically. Vegan D3 is bioequivalent to lanolin-derived D3 in raising 25(OH)D status; the difference is the source organism.

The clinical question of D2 vs D3 has been studied. The literature consistently finds that D3 is more effective per microgram at raising and maintaining 25(OH)D status. The mechanism is debated; the difference is real. For plant-based eaters, this means that vegan D3 from lichen is preferable to D2 from yeast as the supplementation default.

Why supplementation is the default for most plant-based eaters

Three reasons:

  1. Cutaneous synthesis is unreliable. UVB synthesis of vitamin D in skin requires sufficient UVB exposure, which is reduced by latitude (winter at >35 degrees N, sunlight is insufficient for synthesis), by skin pigmentation (darker skin requires longer exposure), by sunscreen use, and by indoor lifestyles. Most modern adults have insufficient cutaneous synthesis to maintain 25(OH)D in the recommended range.
  2. Dietary contribution is small. Without fortified dairy and fatty fish, plant-based dietary vitamin D comes from fortified plant milks (typically 100 IU per cup), UV-exposed mushrooms (variable), and fortified breakfast cereals. Hitting daily targets from food alone requires consistent consumption of multiple servings of fortified products.
  3. Targets are higher than commonly assumed. The Institute of Medicine recommends 600 IU/day for most adults and 800 IU/day for adults over 70. Many clinical endocrinologists target 25(OH)D status of 30-50 ng/mL and recommend supplementation doses (1000-2000 IU/day for most adults) that exceed the IOM dietary recommendation. The clinical literature on optimal 25(OH)D is contested, but the practical default of 1000-2000 IU/day vegan D3 is well-supported.

Plant-food vitamin D sources

Per typical serving:

A plant-based eater consuming 2 cups of fortified plant milk and a cup of UV-exposed mushrooms daily reaches roughly 600 IU. Hitting the 1000-2000 IU clinical target from food alone is impractical for most plant-based eaters; supplementation is the simpler answer.

Clinical assessment

The standard clinical marker is 25-hydroxyvitamin D (25(OH)D), measured in serum. The target range is contested:

For most plant-based clients, hitting 25(OH)D >30 ng/mL is a reasonable conservative target, achievable with 1000-2000 IU/day vegan D3 supplementation in most non-deficient adults. Clients with documented deficiency (25(OH)D <20 ng/mL) require higher doses for replenishment; this is the clinician’s protocol.

How tracking apps handle vitamin D

The audit:

For plant-based clients monitoring 25(OH)D status under clinical care, prefer Cronometer or PlateLens.

Special populations

Pregnancy and lactation. Vitamin D demand increases. Plant-based pregnant clients should hit at least 1000 IU/day from supplementation and confirm dosing with the obstetric provider.

Older adults. Cutaneous synthesis decreases with age. Higher supplementation dose (1000-2000 IU/day vegan D3) is reasonable for plant-based older adults.

Higher-pigmentation skin. Cutaneous synthesis is reduced. Supplementation case is stronger; consider 25(OH)D testing if not previously done.

Northern latitudes / indoor workers. Effectively all of the above. Year-round supplementation rather than seasonal.

Summary

Most plant-based eaters need vitamin D supplementation. Lichen-derived vegan D3 at 1000-2000 IU/day is the default recommendation, supported by the literature and well-tolerated. Tracking should be done in an app that recognizes vegan D3 entries (Cronometer, PlateLens). 25(OH)D testing every 1-2 years is reasonable for plant-based clients and is sometimes covered by primary-care clinicians.

Citations: Institute of Medicine Dietary Reference Intakes for vitamin D; Endocrine Society Clinical Practice Guidelines; American Journal of Clinical Nutrition (multiple on D2 vs D3 efficacy); Journal of the Academy of Nutrition and Dietetics.

Topics: vegan vitamin D · vegan D3 lichen · plant-based vitamin D · vitamin D supplementation vegan