“Assuming you’re consuming many fruits and vegetables, you’re also getting more phytochemicals and antioxidants from your diet,” she says. Both these powerful substances significantly reduce the risk of chronic illnesses.
Con: Vegan diets are lacking in some vital nutrients.
Unfortunately, a diet that excludes all animal products does have some nutritional drawbacks.
Rodriguez cites calcium, omega-3 fatty acids, vitamin B-12 and folate—all of which are present in meat and dairy—as key nutrients a vegan diet can lack. Over time, inadequate consumption of these can result in a host of problems, including loss of bone and muscle mass, she says.
The reduced or even (in some extreme cases) non-existent levels of vitamin B-12 in a strict vegan diet are of particular concern to Keller. Vitamin B-12 has many implications for the smooth running of the central nervous system and for optimizing metabolic functions and in her view, it’s very difficult to get adequate amounts of B-12 from fruits and vegetables alone.
“If you’re not getting enough B-12, you may feel weakness, fatigue, constipation, and lack of appetite,” Keller says. “Without proper amounts of B-12, an infant cannot thrive, and as we age, we have fewer of the gastric acids that synthesize the B-12 from foods, so that’s why my recommendation for B-12 is so strong.”
Pro: There are alternative sources of B-12, one of those important nutrients.
While Mangels—who has been a vegan for 25 years—agrees that vitamin B-12 is only found in meat, dairy and eggs, she also points out that there are plenty of other sources for this important nutrient that many vegans can and do include in their diets. Vitamin B-12 is present in fortified foods, including cereals and plant milk (soy and other), in tofu, and in nutritional yeast, she says.
And while Rodriguez advocates a “foods first” philosophy, she also believes that “there is a sound rationale for supplements,” for vitamin B-12 and other key nutrients, which many vegans do take. Her caveat there, though, would be to ensure that supplements “are taken with reason and not in excess to avoid toxicity.”
Pro: It’s getting easier and easier to buy plant proteins.
The United Nations has declared 2016 as The International Year of Pulses, to heighten public awareness of their nutritional benefits and their importance to sustainable agriculture and food security worldwide.
Pulses, an important faction of the broader legume family, have been a staple food of many cultures around the world for centuries and they are just one example of the numerous forms of alternative protein sources that are now available for those who don’t eat meat or consume dairy.
While animal products offer a complete package of all the essential amino acids that our body needs (and are an omnivores go-to for them), pulses—which include dried peas, kidney beans, chickpeas, fava beans, black beans and adzuki beans, among others—are an unparalleled source of complete plant protein, Montag says, containing all the essential amino acids we require.
Con: Relying on pulses for protein can bring on…discomfort.
But getting the most out of legumes, pulses and other alternative forms of protein requires paying constant attention to combining them with the right grains to ensure proper nutrition, something that many Americans still find difficult to do, Keller says, because it requires a certain amount of planning.
Digesting alternative protein sources can also prove challenging to people who are not used to them: “They can make you feel bloated, they can make your digestive tract feel off,” Keller says. “Many people will feel bad because of this as their system adjusts and they’re not making the necessary adjustments as far as hydration goes to accommodate these new protein sources, so they just feel uncomfortable.”
Pro: Veganism is more environmentally sustainable.
That it takes approximately 1,600 gallons of water to produce a single pound of beef is no secret. Scientists established that fact more than a decade ago and they have also shown that producing one pound of animal protein requires about 100 times more water than producing one pound of grain protein.