People go vegan for three broad reasons: health, environmental impact, and animal welfare. Often it’s a combination of all three. Each motivation is backed by a growing body of evidence showing that removing animal products from your diet changes your body, your resource footprint, and the food system in measurable ways.
Heart Disease and Diabetes Risk
The most consistent health finding is cardiovascular. People who follow vegan or vegetarian diets see roughly a 15% reduction in their risk of developing cardiovascular disease compared to omnivores. Their risk of dying from heart disease drops by about 8%. These numbers come from large pooled analyses, not single studies, which makes them more reliable.
The mechanism is straightforward. Plant-based diets tend to be lower in saturated fat and cholesterol while higher in fiber, potassium, and protective plant compounds. Over time, this translates into lower blood pressure, lower LDL cholesterol, and less arterial inflammation. The same dietary pattern also improves insulin sensitivity, which is why vegans consistently show lower rates of type 2 diabetes in population studies.
What Happens in Your Gut
A vegan diet is naturally high in fiber, and fiber is the primary fuel source for the bacteria living in your digestive tract. When gut bacteria break down fiber, they produce short-chain fatty acids, molecules that help maintain the intestinal lining, regulate inflammation, and support immune function. A diet low in fiber, typical of Western eating patterns, can permanently reduce the diversity of gut bacteria and even cause certain beneficial species to disappear entirely. Increasing plant food intake reverses some of that loss by feeding a wider range of bacterial populations.
The Environmental Case
Environmental impact is the reason that has grown fastest in recent years. The numbers are striking. Producing protein from beef requires up to ten times more land than producing the same amount of protein from cereals or legumes. For soy specifically, the gap is even wider: 100 grams of beef protein needs about 70 times more land than the same amount of soy protein.
Water tells a similar story. One kilogram of beef requires nearly 40 times more water than the same weight of vegetables across all stages of production. A single half-cup serving of boiled lentils uses around 246 liters of water, a fraction of what any equivalent amount of beef demands.
When researchers tracked the full carbon footprint of different diets, from farm to home, a vegan diet produced about 2.1 kg of CO2 equivalents per day. An omnivorous diet produced 3.8 kg. That’s a 46% reduction in daily greenhouse gas emissions, essentially cutting your food-related carbon footprint in half. Even shifting from a pescatarian diet (3.2 kg/day) to a vegan one makes a meaningful difference.
Animal Welfare
For many vegans, the ethical argument is the starting point. Modern animal agriculture involves intensive confinement, selective breeding for rapid growth that causes physical problems in the animals, and slaughter at a scale of tens of billions of land animals per year globally. People who go vegan for ethical reasons view these practices as unnecessary given that humans can meet their nutritional needs from plants. This motivation is harder to quantify than health or environmental data, but surveys consistently rank it as the single most common reason people identify as vegan rather than simply “plant-based.”
Protein: The Most Common Concern
The first question most people ask about veganism is where the protein comes from. Plant proteins do score lower than animal proteins on digestibility measures, with one important exception: soy protein isolate scores a perfect 100 on the standard protein quality scale (PDCAAS), matching whey and egg. Other plant sources score lower. Yellow split peas land around 73 on a related scale, and wheat gluten sits at just 25, making it a poor standalone protein source.
In practice, this means vegans need to eat a variety of protein sources rather than relying on a single food. Combining legumes, whole grains, nuts, seeds, and soy products throughout the day provides all essential amino acids in adequate amounts. You don’t need to combine them at every meal, just across the day. Most vegans in developed countries get enough total protein without difficulty. The issue isn’t quantity so much as variety.
Nutrients That Need Attention
Vitamin B12 is the one nutrient you cannot reliably get from a vegan diet without supplementation. B12 is produced by bacteria and accumulates in animal tissues, so plant foods contain virtually none unless fortified. The consequences of ignoring this are real: studies find B12 deficiency in roughly 50 to 70% of vegans across multiple countries, and one European comparison found deficiency rates of 92% among vegans versus 11% among omnivores.
Deficiency develops slowly, sometimes over years, because the body stores B12 in the liver. Early symptoms include fatigue, tingling in the hands and feet, difficulty concentrating, and mood changes. Left untreated, it can cause irreversible nerve damage. A daily supplement of 50 to 100 micrograms prevents this entirely. Some vegans prefer fortified foods like nutritional yeast, plant milks, or breakfast cereals, but supplementation is the most reliable approach. The European Food Safety Authority recommends at least 4 micrograms per day for the general population, though vegans typically need a higher supplemental dose because absorption from supplements is less efficient than from food.
Iron, zinc, omega-3 fatty acids, and calcium also require more deliberate planning on a vegan diet. None are impossible to get from plants, but absorption rates differ. Plant iron, for example, is less readily absorbed than the form found in meat, so eating vitamin C-rich foods alongside iron-rich beans, lentils, or spinach helps your body take in more.
Why People Stay
Most people try veganism for one primary reason but stay for the overlap. Someone who starts for environmental reasons notices they feel lighter after meals. Someone motivated by animal ethics discovers their cholesterol has dropped. The practical reality is that a well-planned vegan diet delivers measurable benefits across multiple dimensions: lower disease risk, a significantly smaller environmental footprint, and alignment with values around animal welfare. The trade-off is that it requires more nutritional awareness, particularly around B12, protein variety, and mineral absorption, than an omnivorous diet does. For many people, that trade-off feels increasingly worth making.