13 Pros and Cons of Veganism: What the Latest Research Actually Says

Background: What Is a Vegan Diet in 2026?

A vegan diet contains only plant-based foods — no meat, fish, dairy, or eggs. In contrast, vegetarian diets typically include milk, eggs, and sometimes fish.

Globally, veganism is still a small slice of the population — estimated at around 1–5% depending on the country — but adoption is accelerating. In the UK, the vegan population grew 2.4-fold between 2023 and 2025, reaching nearly 5% of adults. In Germany, it doubled between 2016 and 2020. In the United States, interest in plant-forward eating continues to rise even among people who don't label themselves vegan.

Modern agriculture — vegan or not — has changed dramatically since early plant-based diet studies were conducted. Most existing research still draws on data from the 1970s and 1980s, and no long-term randomized controlled trials on a fully vegan diet exist as of this writing. That caveat should be held in mind throughout every point below.

Pros & Cons of Veganism at a Glance

1. Vegans Could Eat More Vegetables — But Often Don't

Probably the biggest theoretical advantage of a vegan diet is vegetables. The average American diet remains woefully short on vegetables, herbs, and spices. Research consistently shows that eating a wide variety of vegetables reduces the risk of heart disease, hypertension, and certain cancers.

Broccoli, cabbage, carrots, cauliflower, leafy greens, peppers, and more should be a cornerstone of anyone's diet — vegan or not.

However, in my clinical experience, many people who adopt a vegan label end up leaning heavily on processed replacements: pasta, sugary snacks, frozen meals, mock meats, and ultra-processed plant milks. This makes it genuinely hard to sustain a healthy vegan diet, as opposed to merely a plant-label diet.

2. Disease Risk: What the Updated 2024 Data Shows

The evidence on veganism and disease has grown meaningfully since 2020. A landmark 2024 review published in PLOS ONE examined 49 studies spanning 23 years of research and found that plant-based and vegan diets are associated with better markers for cardiovascular health and reduced cancer risk factors. The review linked vegan diets to lower cholesterol, lower blood pressure, and reduced incidence of certain cancers including kidney, liver, lung, and prostate cancer.

A separate 2025 systematic review focused specifically on randomized controlled trials found that vegan diets improved several metabolic markers in adults. However, well-balanced omnivorous diets like the Mediterranean or DASH diet have also demonstrated substantial cardiometabolic benefits — a point often overlooked in vegan advocacy.

Bias in nutrition research remains a documented concern. Conflicts of interest — including funding from plant-based food companies — continue to shape how findings are framed and communicated to the public. A 2020 article in the Journal of the American Medical Association spotlighted questionable funding behind prominent pro-plant-based advocacy organizations.

3. Less Biodiversity

Many people go vegan out of a genuine love for animals — a motivation I deeply respect. But the ecological picture is more complex than "no meat = no harm."

Mass-produced vegan crops — particularly soy and legumes — rely heavily on monoculture agriculture, synthetic fertilizers, herbicides including glyphosate, and heavy tilling. These practices degrade topsoil, reduce soil biodiversity, disrupt local ecosystems, and harm pollinators. According to regenerative agriculture experts like Dr. Allen Williams, 95% of crops today are grown under highly artificial conditions.

Animal presence on managed grasslands — when done regeneratively — actually helps sequester carbon, restores soil microbiology, replenishes aquifers, and supports plant biodiversity. The presence of grazing animals is part of a natural ecosystem cycle; monocrops are not.

4. Fiber Intake Can Be Higher on a Vegan Diet — But Choose Carefully

Fruits, vegetables, nuts, seeds, and whole grains provide substantial fiber. Most Americans are chronically under-consuming fiber, so a well-planned vegan diet can help close this gap. Adequate fiber feeds beneficial gut bacteria, supports healthy cholesterol, and strengthens immune function.

However, many vegan staple proteins — soy, wheat, and legumes — contain significant anti-nutrients:

• Phytates — bind to minerals and reduce absorption
• Lectins — can irritate the gut lining, especially in sensitive individuals
• Oxalates — can contribute to kidney stones and impair calcium absorption

Traditional preparation methods like soaking, sprouting, and fermenting significantly reduce these compounds. In clinical practice, most people aren't taking these steps. Additionally, non-organic grains and legumes may carry glyphosate residue — a chemical associated with microbiome disruption.

For people with leaky gut, autoimmune disease, or IBS, high-lectin vegan diets can worsen symptoms rather than help them. See also: Best Fiber for IBS-D.

5. Different, Not Better Antioxidants

Plant foods provide thousands of antioxidants — vitamin C, vitamin E, carotenoids, polyphenols, flavonoids, and many more. This is a genuine strength.

However, a purely plant-based diet tends to be lower in certain critical antioxidants:

• Zinc — an antioxidant mineral concentrated in meat and seafood
• Selenium — essential for thyroid function and immune defense; richest in Brazil nuts and organ meats
• Glutathione precursors — particularly the amino acid methionine, which is low in vegan diets
• CoQ10 — supports mitochondrial energy and is far more bioavailable from animal sources

Grass-fed and regeneratively raised beef, organ meats, and wild-caught seafood are distinctly more nutrient-dense than conventional feedlot equivalents. This nuance is often lost in diet comparisons. Learn more about the health benefits of grass-fed beef.

6. More Carotenoids, But No Carnitine, Choline, or CLA

Plant-based diets deliver impressive amounts of cancer-fighting carotenoids — beta-carotene, lycopene, lutein, and zeaxanthin — which may support blood pressure regulation and eye health. These are genuine wins.

What's missing from plants:

Carnitine

Carnitine is essential for fat metabolism, particularly as we age. It may also support nerve function, reduce neuropathic pain, improve immune function in diabetics, and show promise in neurodegenerative conditions like Alzheimer's disease. Research on carnitine continues to grow. Vegans produce less carnitine endogenously and consume virtually none from food.

Choline

Choline is essential for brain development and neurotransmitter synthesis. Alarmingly, an estimated 90% of Americans don't meet choline requirements — and vegans face the highest risk of deficiency because top food sources (eggs, liver, grass-fed beef) are all animal-based. Vegan choline supplements are available and important for anyone on a plant-based diet. See also: Organ Meats for Women.

CLA (Conjugated Linoleic Acid)

CLA is a unique healthy omega-6 fat found in highest concentrations in grass-fed beef and dairy. It is not present in plants, and is present in only tiny amounts in conventionally raised meat. CLA supports healthy body composition and is notably different from the inflammatory omega-6 fats found in seed oils. Synthetic CLA supplements are not recommended as they do not confer the same benefits.

7. Plenty of Iron in Plants — But It Isn't Well Absorbed

Plant foods contain non-heme iron, which the body absorbs at 2–20% efficiency depending on diet composition and genetics. Heme iron from animal sources is absorbed at 15–35%. Many popular vegan protein sources prominently advertise iron content without disclosing this absorption gap.

Ferritin — the storage form of iron — is the most clinically useful marker to check. Vegans and vegetarians should ask their doctor for regular ferritin testing, not just serum iron. If you're curious about your iron status, read more about iron myths and facts.

Good vegan iron sources include moringa, mulberries, prunes, pumpkin seeds, blackstrap molasses, lentils (soaked/sprouted), and some varieties of mushrooms. Always pair with vitamin C-rich foods to enhance absorption.

8. Plenty of Zinc — But Absorption Is Still the Problem

Zinc in plant foods like beans and whole grains is plentiful in quantity but poor in bioavailability, primarily due to phytate binding. Vegans following high-grain diets may consume adequate zinc on paper but absorb significantly less in practice. Zinc deficiency is difficult to detect because serum zinc is a poor clinical marker.

Zinc is also a critical antioxidant and immune mineral. Both vegans and non-vegans should prioritize zinc-rich foods — for omnivores, oysters, wild-caught salmon, and grass-fed beef are top sources. Vegans may benefit from supplementing moderate doses of zinc, especially during illness or stress.

9. Vitamin B12: The Most Critical Nutrient Gap

B12 deficiency is the most well-documented nutritional risk on a vegan diet, and the consequences — including irreversible neurological damage — are serious. According to the American Journal of Clinical Nutrition, vegan diets are predisposed to deficiencies in vitamin B12, vitamin D, calcium, and omega-3 fatty acids.

The critical nuance: plants contain largely inactive or analogue forms of B12 that can actually interfere with true B12 absorption. Algal B12 and some fortified foods exist but have variable bioavailability. A 2025 pediatric position paper confirmed that supplementation is essential — not optional — for vegan children and adults alike.

Even many omnivores are B12 deficient, particularly those on acid-blocking medications or with gut conditions that impair absorption. This is not exclusively a vegan problem — but the risk is substantially higher without animal foods.

10. The Wrong Omega-3 Fats

Plant omega-3 — alpha-linolenic acid (ALA) found in chia seeds, flaxseed, walnuts, and hemp — is abundant in vegan diets. The problem is conversion. The body must convert ALA into the active forms EPA and DHA, which support brain function, cardiovascular health, and inflammation control.

Recent research confirms that vegans not taking EPA/DHA supplements consistently show low omega-3 status — even when ALA intake is high. Algae-based EPA/DHA supplements are the best solution for vegans and are now widely available. Learn more about choosing the right omega-3 supplement.

DHA is particularly important for brain health and cognitive aging. Vegans who don't supplement may face elevated risk of cognitive decline, though long-term vegan-specific studies are still limited.

11. You Can Meet Protein Needs — But Amino Acid Gaps Remain

The building blocks of protein are amino acids. Not all plant proteins provide a complete amino acid profile, and some amino acids are nearly absent from vegan diets:

Methionine

An essential sulfur amino acid that is needed to produce the master antioxidant glutathione. Vegan diets are significantly lower in methionine than omnivorous diets. Elderly individuals and those with autoimmune conditions are most vulnerable.

Taurine

A conditionally essential amino acid found exclusively in animal foods. It supports cardiovascular function, energy metabolism, and immune defense. Vegan blood levels of taurine are consistently lower than in omnivores, and the body's ability to synthesize it from cysteine declines with age.

Lysine

Found in plant foods like legumes but in lower amounts than in meat. Lysine is critical for muscle synthesis, collagen production, and immune function. Many vegans don't eat enough lysine-dense foods consistently.

12. It Depends on Your Genes

Nutrigenomics — the study of how genes and diet interact — has made it clear that there is no single "best" diet for every human. Several key genes influence how well your body handles a vegan diet:

Consumer genetic testing (23andMe, etc.) can reveal some of these variants, particularly BCO1 and MTHFR. Functional medicine practitioners can help interpret results in the context of your full health picture. For a deep dive into functional nutrition, visit The Healthy RD.

13. Ecosystem: The Updated, More Nuanced Picture

The environmental impact of food is genuinely complex, and 2024–2025 research adds important nuance to the debate.

What the Latest Science Shows

A 2025 study published in Frontiers in Nutrition found that a vegan diet can cut carbon footprint by roughly 46% and reduce agricultural land use by 33% compared to an omnivorous baseline. A large UK Nature Food study of 55,504 participants confirmed that vegan diets produced only about 25% of the greenhouse gas emissions of high meat-eaters.

The Monocrop Problem Still Stands

Even with improved emissions data, the monoculture problem hasn't gone away. Soy, corn, and most legume crops are produced through farming systems that:

• Destroy topsoil at an alarming rate through heavy tilling
• Require synthetic nitrogen fertilizers, fungicides, and herbicides
• Eliminate native plant and animal species through habitat simplification
• Create chemical runoff into waterways

As dietitian Kasey Hutchinson, RD of Vibrant Nutrition explains: "Imitation vegan meats are often produced with bioengineered/genetically modified ingredients like corn and soy — products of mono-crop agriculture that is destroying topsoil at an alarming rate. Eating out-of-season produce flown in from across the world may be worse for the environment than eating local chicken."

The Regenerative Middle Path

The most promising framework may not be "vegan vs. omnivore" but rather regenerative vs. extractive farming. Properly managed grass-based animal systems can:

• Sequester atmospheric carbon in soil
• Restore underground aquifers through improved water infiltration
• Increase plant biodiversity and support pollinator populations
• Eliminate the need for synthetic inputs

Permaculture systems — which integrate animals, diverse crops, and native plants — represent a genuinely sustainable alternative that the "just go vegan" narrative misses entirely. Whatever your diet, know your farmer and support regenerative practices.

Heidi Moretti, MS, RD, CLT — The Healthy RD

Heidi is a registered dietitian with over 25 years of clinical experience specializing in functional nutrition, gut health, and natural medicine. She is the bestselling author of Cortisol Fix, Period Fix, Gut Fix, and The Whole Body Guide to Gut Health. Learn more about Heidi →

This post is for educational purposes only and is not medical advice. Always speak with your healthcare provider before making changes to your health regimen.