Your body needs certain important nutrients like B12, taurine, and omega-3s, and these are mostly or only found in animal foods like meat and fish — you can't really get them from plants.

We analyzed 18 studies and found no evidence that vitamin B12, carnosine, taurine, DHA, or EPA are reliably available in plant-based foods. These nutrients are primarily found in animal products like meat, fish, eggs, and dairy. Vitamin B12 is essential for nerve function and red blood cell production, while taurine and carnosine play roles in muscle and brain health. DHA and EPA are omega-3 fats important for heart and brain function. The evidence we’ve reviewed suggests that plants do not naturally contain these compounds in meaningful amounts, and no plant source has been shown to consistently provide them without fortification or supplementation [1]. While some algae-based supplements can deliver DHA and EPA, these are derived from marine sources, not land plants. Similarly, B12 found in fermented foods or algae is often inactive in humans and does not meet nutritional needs. We have not seen any studies showing that whole, unfortified plants provide these nutrients in amounts that support human health. What we’ve found so far points to animal foods as the primary natural source for these compounds. If you avoid animal products, you may need to rely on fortified foods or supplements to meet your needs for these nutrients.