The decision. For someone eating (or transitioning to) a vegetarian or vegan diet, which nutrients actually need attention — through food pairing, fortification, or a supplement — and for whom? This is the multi-nutrient generalization of the B12 question -> Vitamin B12 Status in Vegetarian and Vegan Diets: B12 is the sharpest single case, but a plant-based diet shifts the deficiency-risk profile of a whole panel of nutrients at once. The single source held is a gold-tier systematic review of nutrient intake and status in adults on plant-based vs meat-containing diets — 141 studies, mostly Europe / South-East Asia / North America (Neufingerl & Eilander, 2021). It reports prevalence and biomarker facts, not effect estimates on any patient-important outcome — the same surrogate discipline the B12 page carries applies to every nutrient here -> Surrogate Outcomes.
Source COI — read the data, discount the framing (symmetric standards)
Both authors are Unilever employees (Unilever Foods Innovation Centre), and Unilever sells plant-based products (Neufingerl & Eilander, 2021). The specific bias risk is an adequacy-favorable tilt. Held to the same bar as a meat-industry-funded SR reaching the opposite conclusion, the split is:
- The empirical layer is the core and is even-handed. The prevalence/status data cut against plant-based diets exactly where the biology says they should (B12, D, iron, zinc, iodine, calcium, EPA/DHA all lower), and honestly report meat-eaters at risk of fiber, PUFA, ALA, folate, vitamin E, D, calcium and magnesium: «There were nutrient inadequacies across all dietary patterns, including vegan, vegetarian and meat-based diets» (Neufingerl & Eilander, 2021). A tilted review would have buried the plant-diet deficits; this one tabulates them. Credit the data.
- The interpretive layer runs ahead of this review’s own evidence. The abstract’s framing sentence — «As plant-based diets are generally better for health and the environment, public health strategies should facilitate the transition…» (Neufingerl & Eilander, 2021) — imports a health-and-environment verdict this review did not measure: it assessed nutrient biomarkers, not disease outcomes, and holds no environmental data at all. The “generally better for health” claim is borrowed from cited EAT-Lancet/GBD references, not produced here. Do not launder it: this review’s own finding is that a plant-based diet creates several real deficiency risks that require active management, which is a narrower and more useful claim than the framing headline .
The COI conditions the interpretive claims; it does not disqualify gold-design prevalence counts. The non-health axis (environment) is named and dropped, never priced in here — the wiki holds no environmental data (the one axis, named rule).
The reframe — intake, bioavailability, and status are THREE different objects
The most decision-relevant move is a unit-of-analysis shift: what you eat (intake) is not what you absorb (bioavailability) is not what your blood shows (status), and on a plant-based diet these three can point in opposite directions (Neufingerl & Eilander, 2021). Iron and zinc are the clean demonstrations:
- Iron — intake is HIGHER in plant diets, status is LOWER. Vegans out-eat meat-eaters on iron (21.0 vs 13.9 mg/d), yet serum ferritin runs the other way (meat 55.5 vs vegetarian 33.8 vs vegan 31.3 ug/L; vegetarian women particularly low at 24.3), with iron-deficiency prevalence 7% / 11% / 15% and anemia 5% / 11% / 17% (meat / vegetarian / vegan) (Neufingerl & Eilander, 2021). The gap is bioavailability: «iron bioavailability in a plant-based diet is substantially lower (i.e., ~10%) compared to a diet with meat and fish containing heme iron (18%)… Heme iron is more efficiently absorbed (15-40%) than non-heme iron (1-15%) which is inhibited by phytates, polyphenols and proteins» (Neufingerl & Eilander, 2021) -> Antinutrients in Plant Foods. IOM sets the plant-diet iron requirement 1.8x higher for this reason.
- Zinc — intake SIMILAR, status LOWER. Mean zinc intake is comparable across patterns, but against the bioavailability-adjusted EAR (phytate inflates the requirement up to +50%) vegetarians and vegans fall short for men, status is lower (0.79-0.81 vs 0.90 mg/L), and deficiency reaches 30% in vegans vs 13-14% otherwise (Neufingerl & Eilander, 2021).
Decision consequence: a plant-diet intake number that “meets the EAR” can still leave a real status shortfall, so an unadjusted intake comparison is the wrong instrument for iron and zinc — use the bioavailability-adjusted requirement, and prefer status (biomarker) over intake (self-report) wherever both are reported, since self-reported intake carries the larger error -> Measurement Error in Dietary Assessment. The zinc case also carries a counter-caveat the authors state plainly: «there are no reported adverse health consequences in adult vegetarians with lower zinc status, suggesting that the efficiency of zinc utilization may be increased in vegetarians on the longer term» (Neufingerl & Eilander, 2021) — lower zinc status here is a surrogate whose transmission to harm is itself unestablished, exactly the Surrogate Outcomes discipline.
The at-risk panel, by stratum
Risk is stratum-graded: vegan > vegetarian > meat-eater for the animal-sourced nutrients, and reversed for the plant-abundant ones. Magnitudes below are means benchmarked to the EAR (or AI/AMDR where noted), plus deficiency-prevalence where a biomarker cutoff existed (Neufingerl & Eilander, 2021).
| Nutrient | Highest-risk stratum | Signal (intake vs requirement · status · deficiency %) | Why plant diets fall short |
|---|---|---|---|
| Vitamin B12 | vegan >> vegetarian | intake vegan 1.5 / veg 2.1 / meat 5.6 ug/d (EAR 2.0, food-only vegan well below); deficiency ~44% vegan, ~32% vegetarian | essentially no active plant source |
| EPA/DHA | vegan, vegetarian | intake vegan 27/4, veg 16/31, meat 94/172 mg/d — below 250 mg AMDR; status consistently lower | fish/seafood absent; ALA->EPA/DHA conversion <10% |
| Iodine | vegan | intake vegan 111 / veg 146 / meat 170 ug/d (EAR 95); deficiency (UIC<100) 92% vegan vs 37% veg vs 51% meat | few plant sources; thin: 5 studies on intake, 5 on status, 3 on deficiency prevalence |
| Iron | vegetarian/vegan women | intake higher but ferritin lower; deficiency 15% vegan / 11% veg / 7% meat; anemia up to 17% | non-heme, phytate-inhibited (see reframe) |
| Zinc | vegan | intake similar but below adjusted EAR; deficiency 30% vegan | phytate-inhibited absorption |
| Vitamin D | vegan (but ALL patterns) | intake below EAR (10 ug) in every pattern (vegan 1.52 -> pesco 5.25); deficiency 67% vegan / 33% veg in one small Finnish study | few natural sources; a whole-population gap |
| Calcium / bone | vegan | intake vegan lowest (838 mg, EAR 800); higher PTH + bone-turnover markers in veg/vegan, lower lumbar-spine BMD in vegans | lower intake + phytate/oxalate absorption drag |
| Protein | (older) vegans | lower %E (veg 13.4 / vegan 12.9 vs meat 16.0) but all above the 10%E AMDR; quality ~80-90% | lower digestibility; a concern mainly for older adults |
The mirror finding (symmetric standards). Meat-eaters are the at-risk stratum for the plant-abundant nutrients — fiber, PUFA, ALA, folate, vitamin E, magnesium — and, alongside everyone else, vitamin D and calcium (Neufingerl & Eilander, 2021). “Nutrient inadequacy” is not a property of plant-based diets; it is a property of any non-diverse diet, differently distributed.
What each risk actually licenses (the levers, not a prescription)
Mapping onto Deficiency Repletion vs Enhancement: these are repletion-territory cases (correcting a real dietary shortfall in an identified stratum), not enhancement of the replete — so the lever can matter, but the review holds no outcome effect, only the shortfall. The source’s own tiering of remedies:
- Fortification / supplementation (structural gap, no good food fix): B12 (absent from plant food), vitamin D and iodine (few natural sources) — these need fortified foods, iodized salt, or supplements regardless of dietary pattern (Neufingerl & Eilander, 2021). B12 is the non-optional one -> Vitamin B12 Status in Vegetarian and Vegan Diets. Iodine cross-links the deficiency arm here, distinct from the excess arm -> Excess Iodine Intake and Thyroid Disease and the pregnancy stratum -> Iodine Supplementation in Pregnancy.
- Bioavailability / pairing (food is adequate, absorption is not): iron and zinc — pair with vitamin-C foods, use soaking/fermentation to cut phytate, and count the adjusted requirement, not the raw intake.
- Diet diversity (a real food fix exists): calcium (leafy greens, pulses, fortified plant milks), EPA/DHA (algae oil the only direct plant source), fiber/vitamin E in the vegetarians who eat too few whole plant foods.
The choice among these stays the person’s (layer 3); supplement selection/dosing needs this person’s labs and is a prescriber act out of scope.
Relationship to Pawlak (B12) — type-F broadening, NOT independent corroboration
Neufingerl broadens the held B12 finding (Pawlak 2013) from one nutrient to a whole panel, and on B12
specifically it adds the omnivore comparator Pawlak lacked (Pawlak reported one-arm vegetarian
prevalences only). That is type-F refinement/broadening, not type-E independent backing — a wider
review filling a gap, not a second independent witness to the same quantity. The B12 parameter comparison
is built on the B12 page. No [E-independent] is claimed here
.
Confidence and gaps
Confidence medium — gold-design SR, but a single source, all endpoints are surrogates (intake/status,
no patient-important outcome), and the industry COI conditions the framing (not the counts).
Key limitations and gaps (G):
- No patient-important outcome anywhere. Every finding is intake or biomarker status; whether correcting any of these shortfalls changes a hard endpoint is unheld. — outcome effect of correcting plant-diet nutrient shortfalls (iron/zinc/iodine/D/omega-3) on patient-important endpoints`
- True inadequacy prevalence could not be estimated. The authors compared means to the EAR rather than the proportion of the population below it: «A major limitation of our review was that we could not provide reliable estimations on the adequacy of dietary nutrient intakes» (Neufingerl & Eilander, 2021). Read the prevalence numbers as indicative, not exact — and this cuts against over-reading the deficits.
- Iodine and EPA/DHA rest on very few studies (iodine 5 on intake and 5 on status, with the 92% deficiency figure resting on 3; EPA/DHA 8) — insufficient-evidence, not a firm parameter, despite the dramatic 92% vegan iodine-deficiency figure. Counts: «Five studies reported on iodine intake», «Five studies reported on iodine status», and «Three studies reported on iodine deficiency» (Neufingerl & Eilander, 2021).
- Western populations only; results may not transport to other food systems.
- Cutoff and measurement heterogeneity drive part of every deficiency band (the same caveat that governs the B12 prevalence range).