Vegan

Vegan diet and longevity: what the science actually shows

A vegan diet excludes all animal products, including meat, dairy, eggs, and honey. When done right, it can deliver measurable health benefits. The Adventist Health Study-2, which tracked over 96,000 people, found that vegans had 15% lower all-cause mortality than non-vegetarians. A 2024 meta-analysis in Frontiers in Nutrition confirmed that plant-based dietary patterns are associated with reduced all-cause mortality risk across multiple cohort studies ^[1]. And a 2025 Nature Communications study analyzing data from 101 countries between 1961 and 2018 found that higher plant-based protein consumption correlated with longer adult life expectancy ^[2].

The mechanisms behind these findings aren't mysterious. Vegan diets tend to be higher in fiber, polyphenols, and phytonutrients while being lower in saturated fat. They also produce lower levels of TMAO (trimethylamine N-oxide), a gut-derived metabolite linked to atherosclerosis that forms primarily from carnitine and choline in animal products ^[3]. A 2024 study of 21,561 individuals in Nature Microbiology showed distinct gut microbiome signatures in vegans, with higher abundance of fiber-fermenting bacteria that produce beneficial short-chain fatty acids ^[4].

The epigenetic aging connection

One of the most striking recent findings comes from the 2024 Twins Nutrition Study (TwiNS), published in BMC Medicine. Researchers assigned 21 pairs of identical twins to either a vegan or healthy omnivorous diet for 8 weeks. The vegan group showed decreased epigenetic age acceleration across multiple biological clocks, including PC GrimAge, PC PhenoAge, and DunedinPACE. Their heart, liver, hormone, and inflammatory system ages all decreased ^[5]. The catch: the vegan participants also lost more weight, which itself affects epigenetic clocks. Still, the controlled twin design makes this one of the strongest pieces of evidence that dietary change can shift biological aging markers in a matter of weeks.

Critical nutrients you can't ignore

A vegan diet isn't automatically healthy. Without planning, it leads to deficiencies that can cause real harm. Here's what to watch:

Vitamin B12 is the non-negotiable supplement. No plant food reliably provides it, and deficiency causes irreversible nerve damage. Take 250-500 mcg of cyanocobalamin or methylcobalamin daily, or 2,500 mcg weekly. Test both serum B12 and methylmalonic acid (MMA) for accurate status assessment.

Omega-3 fatty acids: The body converts only 5-8% of plant-based ALA (from flax, chia, walnuts) into EPA, and even less into DHA. Algae-based DHA/EPA supplements at 250-500 mg combined daily bypass this bottleneck entirely ^[6].

Iron: Plant-based non-heme iron is absorbed at roughly half the rate of heme iron from meat. Eating iron-rich foods (lentils, pumpkin seeds, spinach) with vitamin C dramatically improves absorption. Soaking, sprouting, and fermenting legumes and grains reduces phytates that block iron uptake.

Other gaps: Calcium (aim for 1,000-1,200 mg/day from fortified plant milks, calcium-set tofu, and kale), iodine (150 mcg daily from seaweed or supplements), vitamin D3 from lichen sources, and zinc (pumpkin seeds, chickpeas, cashews) all need attention.

Bone health: a real concern

This is the area where vegans face the most clear-cut risk. A meta-analysis of 20 studies with 37,134 participants found that vegans have lower bone mineral density at the femoral neck and lumbar spine, and significantly higher fracture rates compared to omnivores ^[7]. The EPIC-Oxford study found that vegans had 43% higher rates of total fractures and 2.3 times the risk of hip fractures compared to meat-eaters. However, much of this risk disappears when calcium intake exceeds 525 mg/day. Combined vitamin D and calcium supplementation can bring fracture risk back in line with omnivores ^[8].

Building muscle on plants

The leucine content of plant proteins is lower than whey or eggs, which means you need more total protein to trigger the same muscle protein synthesis response. For active people, aim for 1.8-2.2 g of protein per kg of body weight daily. The best plant protein sources are soy products (tofu, tempeh, edamame), which contain all essential amino acids; legume-grain combinations; seitan at 25g protein per 100g (though low in lysine); and pea-rice protein blends with a PDCAAS approaching 1.0. Creatine monohydrate at 3-5g daily is also worth considering, since vegans have lower baseline creatine stores, and supplementation improves both exercise performance and cognitive function ^[6].

Processed vegan food: not the same thing

The health benefits of vegan eating come from whole plant foods, not from plant-based burgers, vegan cheese, and processed meat alternatives. These products often contain high sodium, refined oils, and ultra-processed ingredients. A 2024 umbrella review in Critical Reviews in Food Science and Nutrition found that the protective associations of plant-based diets apply primarily to whole-food approaches, not processed plant-based eating patterns ^[9]. The distinction matters. A diet of chickpeas, lentils, vegetables, nuts, and whole grains is very different from one built on vegan junk food.