Plant-based diets can fall short on B12, omega-3, creatine, and more. This guide reviews the supplements with the strongest evidence for vegans and vegetarians, and how to prioritize them.
Supplements for Vegans are not a luxury for the plant-based crowd — they are a biochemical necessity. Eliminating animal products removes the most bioavailable dietary sources of several critical nutrients, and while a well-planned vegan diet covers most bases, certain gaps are stubbornly persistent. This article examines the evidence for targeted supplementation, with a particular focus on compounds where human clinical data is strongest.
The Evidence Base
The scientific literature on vegan nutrition has matured significantly over the past decade. Randomized controlled trials (RCTs), systematic reviews, and biomarker studies have moved the conversation beyond opinion and into measurable outcomes. We now have solid data on which deficiencies are most common, which carry clinical consequences, and which supplements reliably correct them.
The most consistently documented gaps in vegan diets include vitamin B12, vitamin D, omega-3 fatty acids (DHA/EPA), iron, zinc, iodine, and creatine. Less discussed but equally important is nicotinamide adenine dinucleotide (NAD+) precursors, particularly nicotinamide mononucleotide (NMN), which has emerged from aging research with promising human trial data relevant to metabolic health — a concern for vegans and omnivores alike.
For B12, the evidence is unequivocal: without supplementation or fortified foods, deficiency is inevitable. The same holds for creatine, where vegan diets provide zero dietary intake and muscle stores run approximately 10–15% lower than in omnivores. For omega-3s, algal DHA/EPA supplements have been shown to raise erythrocyte omega-3 indices comparably to fish oil in head-to-head RCTs. Iron and zinc supplementation require more nuance — absorption is lower from plant sources, and indiscriminate high-dose iron carries risks.
The NMN human trial literature, while younger, is now substantial enough to evaluate. Multiple RCTs have demonstrated that oral NMN supplementation raises blood NAD+ metabolite levels and produces measurable physiological effects in humans.
The Mechanism
To understand why certain supplements matter for vegans, it helps to trace the biochemical logic of each gap.
B12 and the Methylation Cycle
Vitamin B12 (cobalamin) is synthesized exclusively by bacteria and archaea. It accumulates in animal tissues because herbivores harbor these microbes in their digestive tracts. Plants do not contain bioactive B12 unless fortified. B12 serves as a cofactor for methionine synthase and methylmalonyl-CoA mutase — enzymes critical for DNA synthesis, myelin maintenance, and energy metabolism. Deficiency causes irreversible neurological damage. No plant-based workaround exists.
NAD+ Decline and NMN
NAD+ is a coenzyme central to cellular energy production, DNA repair, and mitochondrial function. It declines with age in all humans, regardless of diet. Gomes et al. (2013) demonstrated in Cell that declining NAD+ disrupts nuclear-mitochondrial communication, inducing a pseudohypoxic state that accelerates aging-related metabolic dysfunction. This is not a vegan-specific issue — it is a universal human biology problem.
NMN is a direct precursor to NAD+. Oral NMN is absorbed and converted to NAD+ in tissues. Irie et al. (2020) showed that single doses of 100–500mg NMN in healthy Japanese men significantly elevated plasma NMN and NAD+ metabolite levels within hours, with no adverse effects. Yoshino et al. (2021) extended this to a 10-week RCT in prediabetic women, finding that 250mg/day NMN improved muscle insulin sensitivity — a clinically meaningful metabolic outcome. Igarashi et al. (2022) confirmed in healthy older men that 250mg/day for 12 weeks elevated blood NAD+ levels and altered muscle function biomarkers. Liao et al. (2021) demonstrated enhanced aerobic capacity in amateur runners at 300–1200mg/day. Niu et al. (2023) reported effects on serum metabolism, fecal microbiota, and telomere length in middle-aged adults.
The relevance for vegans: NAD+ precursors are found in trace amounts in some plant foods (avocado, broccoli, edamame), but dietary intake is minimal and poorly characterized. NMN supplementation offers a direct, evidence-backed route to support NAD+ metabolism.
Omega-3 Conversion Bottlenecks
Plant-based diets provide ample alpha-linolenic acid (ALA) from flax, chia, and walnuts. However, conversion of ALA to the long-chain omega-3s DHA and EPA is inefficient in humans — estimated at less than 5% for EPA and under 0.5% for DHA. These long-chain omega-3s are critical for brain structure, cardiovascular function, and anti-inflammatory signaling. Algal oil supplements bypass the conversion bottleneck entirely.
Iron, Zinc, and Bioavailability
Plant iron (non-heme iron) has lower absorption rates than heme iron from meat, and plant phytates further inhibit uptake. Zinc follows a similar pattern. This does not mean vegans are universally deficient — adaptation mechanisms improve absorption over time — but suboptimal status is common, particularly in women of reproductive age for iron.
What the Human Trials Actually Show
It is worth being precise about what the NMN evidence demonstrates, because the supplement space is rife with overclaiming. The human data is real but bounded.
| Study | Population | Dose / Duration | Key Outcome | Evidence Quality |
|---|---|---|---|---|
| Yoshino et al. (2021) | Prediabetic women (n=25) | 250mg/day, 10 weeks | Improved muscle insulin sensitivity | Moderate (small sample) |
| Igarashi et al. (2022) | Healthy older men (n=42) | 250mg/day, 12 weeks | Elevated blood NAD+; altered muscle function markers | Moderate |
| Irie et al. (2020) | Healthy Japanese men (n=10) | 100–500mg single dose | Dose-dependent rise in plasma NMN/NAD+ metabolites | Limited (small, acute) |
| Liao et al. (2021) | Amateur runners (n=48) | 300–1200mg/day, 6 weeks | Enhanced aerobic capacity (VO2-related measures) | Moderate |
| Niu et al. (2023) | Middle-aged adults (n=8) | 300mg/day, 8 weeks | Changes in serum metabolism, microbiota, telomere length | Limited (very small sample) |
The pattern is clear: NMN reliably raises NAD+ related biomarkers in humans, and there are signals of functional benefit for insulin sensitivity, muscle function, and exercise capacity. What is not established are long-term outcomes, optimal dosing for specific populations, or effects in younger healthy adults. The studies are also relatively small and short-term. This is early-phase clinical evidence — promising, but not definitive.
For a deeper dive into what NMN is and how it works, see our guide on What Is NMN. For a breakdown of which benefits have human backing versus which remain speculative, read NMN Benefits: 7 Effects With Actual Human Evidence.
Who Benefits Most
Certain vegan populations face higher deficiency risk and stand to gain more from targeted supplementation.
Older adults are the clearest overlap group. NAD+ declines with age in everyone, and the Igarashi et al. (2022) data in healthy older men suggests NMN can partially reverse this trajectory. Older vegans may face compounding factors: lower B12 stores from decades without intake, reduced sun exposure affecting vitamin D, and age-related declines in nutrient absorption.
Active individuals and athletes represent another high-yield group. Vegan diets provide no dietary creatine, and creatine monohydrate supplementation has been shown in multiple RCTs to improve high-intensity exercise performance and cognitive function in vegans specifically. The Liao et al. (2021) NMN data on aerobic capacity in runners adds another layer for endurance-focused athletes. For dosing considerations, our NMN Dosage Guide breaks down why 250mg has shown effects in trials and where higher doses fit.
Women of reproductive age require particular attention to iron and iodine. Menstrual iron losses increase requirements, and plant-based iron absorption is inherently less efficient. Iodine deficiency is also more prevalent in vegans who do not use iodized salt or seaweed, with implications for thyroid function.
Those with limited sun exposure — common in northern latitudes or indoor occupations — need reliable vitamin D supplementation, as mushrooms and fortified foods rarely provide adequate amounts.
Practical Application: A Tiered Approach
Not every vegan needs every supplement. A rational approach prioritizes based on deficiency risk, consequence severity, and evidence strength.
Tier 1 — Non-negotiable: Vitamin B12. No workaround. Methylcobalamin or cyanocobalamin at 250–1000mcg daily, or 2000mcg weekly. Check serum B12 and methylmalonic acid periodically.
Tier 2 — Strong evidence, high benefit: Vitamin D3 (vegan-derived from lichen), algal DHA/EPA (250–500mg combined daily), and creatine monohydrate (3–5g daily). These address gaps with zero or minimal dietary alternative.
Tier 3 — Conditional based on status and goals: Iron (only if deficient; ferritin testing recommended), zinc (if intake is low or signs of deficiency present), iodine (if not using iodized salt), and NMN for NAD+ support. For those specifically targeting NAD+ metabolism, Bio:sudo NMN 1000mg provides a dose at the upper end of the studied range, though it is worth noting that benefits have been observed at lower doses such as 250mg in the Yoshino and Igarashi trials.
Timing matters. Iron should be taken away from coffee, tea, and calcium-rich meals to maximize absorption. Creatine can be taken any time — consistency matters more than timing. NMN appears to be well-tolerated in morning dosing based on trial protocols, though optimal timing remains under investigation.
What the Evidence Does Not Show
Honesty about limits is as important as highlighting findings.
The NMN literature does not yet demonstrate longevity extension in humans. The Gomes et al. (2013) mechanistic work in Cell established the NAD+-aging link in model systems, but translating this to human lifespan is speculative. No human trial has measured mortality or even major clinical endpoints like cardiovascular events.
We also lack head-to-head data comparing NMN to other NAD+ precursors like nicotinamide riboside (NR) in humans. Both raise NAD+, but whether one is superior for specific outcomes remains unknown.
For vegan-specific nutrition, the interaction between plant-based diets and NMN metabolism has not been directly studied. The trials cited here were not conducted in vegan populations. The rationale for NMN in vegans rests on the universal biology of NAD+ decline and the negligible dietary NMN content in all diets, plant-based or otherwise — not on any vegan-specific NMN deficiency.
Practical Takeaways
- B12 is mandatory — no exceptions, no plant-based alternatives. Test levels annually.
- Algal DHA/EPA is the only reliable vegan source of long-chain omega-3s; ALA conversion is insufficient for brain and cardiovascular needs.
- Creatine monohydrate at 3–5g/day addresses the zero dietary intake in vegan diets and improves both physical and cognitive performance.
- Vitamin D3 from lichen is preferable to D2 for maintaining 25(OH)D levels; dose based on blood testing, not guesswork.
- NMN has human RCT evidence for raising NAD+ and improving metabolic and muscle function markers; it is relevant for vegans due to negligible dietary NMN in all diets, but optimal long-term dosing and vegan-specific effects need more research.
- Iron and zinc should be supplemented only if intake is inadequate or deficiency is confirmed — indiscriminate high-dose supplementation carries risks.
Bottom Line
A well-planned vegan diet is nutritionally adequate for most people, but it does not automatically provide optimal levels of several critical compounds. The evidence for targeted supplementation — particularly B12, vitamin D, algal omega-3s, creatine, and NMN — is strong enough to justify routine use in most vegans. The NMN human trial data is especially noteworthy: it demonstrates measurable metabolic effects at doses as low as 250mg/day, though the field is young and long-term outcomes remain unstudied. Supplementation should be evidence-guided, not fear-driven.
References
- Yoshino M, et al. "Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women." Science. 2021;372(6547):1224–1229. [Source]
- Igarashi M, et al. "Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men." npj Aging. 2022;8(1):5. [Source]
- Irie J, et al. "Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men." Endocrine Journal. 2020;67(2):153–160. [Source]
- Liao B, et al. "Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study." Journal of the International Society of Sports Nutrition. 2021;18(1):54. [Source]
- Gomes AP, et al. "Declining NAD+ induces a pseudohypoxic state disrupting nuclear-mitochondrial communication during aging." Cell. 2013;155(7):1624–1638. [Source]
- Niu KM, et al. "The impacts of short-term NMN supplementation on serum metabolism, fecal microbiota, and telomere length in pre-aging phase." Nutrients. 2023;15(3):755. [Source]