Vegetarian and vegan eating is more popular than ever before for a variety of reasons. This post isn’t about delving into the many reasons why a person might choose this dietary pattern nor is it about splitting hairs over the different ways ‘vegetarianism’ shows up, i.e. no red meat, but yes to eggs & dairy, or no land animals but yes to fish, or ‘flexitarian’ where someone is a ‘sometimes’ vegetarian; a term I loathe. To me, if you eat animal-based foods regardless how often, then you’re not a vegetarian; it’s about a preference but I digress.
I’m going to go beyond some of the more popular nutrients of concern when it comes to being vegan although the usual suspects still stand: vitamin B12, calcium, zinc, iron, vitamin A, and the long chain omega-3 fats EPA & DHA [as opposed to the shorter chain alpha-linolenic acid or ALA, which is not the same as EPA & DHA].
I’m not suggesting that diets which contain animal foods are necessarily healthier but studies show vegetarian and vegan diet need more attention when it comes to certain nutrients. Why? Because philosophies aside, animal foods tend to contain these nutrients in higher amounts and, more importantly, those nutrients are absorbed better/more efficiently.
Nutrients of concern when it comes to vegan diets
Vitamin B12: Vitamin B12 by far the best understood nutrient at risk for vegans. B12 is so crucial for so many physiological functions. There are virtually no vegan sources of B12 which is found abundantly in animal foods. B12 plays an important role in mental health and in preserving cognition as we age. Several studies have confirmed how vegans are at risk for B12 deficiencies and this is especially true for children’s growing brains while following a vegan diet. (1, 2,). Vegans need to be sure to include foods fortified with vitamin B12, use Brewer’s & nutritional yeast and/or supplements.
Signs of impaired cognitive function in adolescents with marginal B12 status
Zinc: Suboptimal intakes of zinc is common, even for omnivores but more so for vegans, Like all minerals, zinc from plant foods isn’t absorbed as efficiently because of anti-nutrients like phytic acid, fiber, saponins etc. Some research puts the decreased absorption at 35% less in a vegan diet and it’s estimated that zinc requirements may be as high as 50% greater for vegetarians due to the lowered absorption.
Bioavailability of iron, zinc, and other trace minerals from vegetarian diets.
Note, it’s not just zinc where requirements are estimated to be higher in vegan diets, it also goes for protein, iron, calcium, and magnesium.
Iron: Iron is found naturally in some plant foods but the reality is, it’s not absorbed as efficiently as it is from animal foods – sorry folks, it’s not a matter of opinion, it’s a matter of fact. It is for this reason that vegans tend to have lower body stores of iron. (6, 7). Like B12, vegans are advised to look for iron-fortified foods, and/or take supplements. Eating acidic or foods rich in vitamin C at meals can modestly increase the amount of iron absorbed from plant foods.
Omega-3 fats EPA & DHA: In the world of omega-3 fats, people routinely use those derived from animals foods (fish, seafood & fortified eggs) interchangeably with those from plant foods [walnuts, canola, flax, chia. Nothing could be more dangerous. Like siblings from the same parent who share a name, they are not the same nor do they behave the same physiologically speaking. Vegans tend to have an excess of the plant-based omega-3 fat alpha-linolenic acid or ALA at the expense of EPA & DHA. This why there’s be a growing market for vegan sources [algae] of EPA & DHA to help fill the gap and to ensure vegans get these precious omega-3 fats. One of my favourite products is NutraVeg by Ascenta Health. One servings provides 400 mg of DHA & the equivalent of about 165 mg EPA.
Vitamins A & D: Beta carotene is not vitamin A which is called retinal/retinol. Preformed vitamin A is only found in animal foods like milk, liver, fish & seafood, organ meats and eggs. It’s true a small amount of beta carotene from orange/green vegetables and orange fruit is converted to vitamin A, the amount is small (8) and not everyone does it to the same degree; some of us convert more than others do. To get the same amount of vitamin A from 1/2 teaspoon of cod liver oil, you’d have to eat 2 cups of carrots, 1 cup of sweet potatoes, and 2 cups of kale – good luck.
Vitamin D typically comes from the sun but is also found in eggs, organ meats, fortified milk and fish. A little vitamin D is found in some mushrooms but consumption remains low which is why vegans typically have 74% lower blood levels of vitamin D compared to omnivores (9) although both vegans and omnivores don’t get enough of this critical vitamin but that’s a different story. For a brief overview, read my post A Primer on Vitamin D.
Choline: A cousin to the B vitamins, choline is a much underappreciated nutrient. See my full post on choline here. It is found in plant foods but like most of the other nutrients in this post, choline is not only found easily in animal foods, it is absorbed well too. Best food sources are liver, egg, fish, milk, turkey, chicken & seafood. Choline is needed for cognition, memory consolidation, and learning and for fetal brain development.
Creatine & carnosine: Creatine is not just for body builders, it’s a form of stored energy for everyone as well. Studies routinely find vegetarians and vegans to deficient in creatine which essentially starves muscles and has detrimental effects on cognition (10, 11 12). Carnosine is type of protein (dipeptide; 2 amino acids) concentrated in the brain and muscles. It’s a powerful antioxidant, and helps to prevent some of the negative effects of degenerative diseases like diabetes, cardiovascular disease, and more. Like creatine, carnosine is only found in animal foods (13).
Methionine: It is an essential amino acids meaning that the diet must provide it unlike other amino acids which the body can produce on its own. Methionine is low in plant foods unlike animal foods. Most fruits and vegetables contain very little of it and most pulses [chickpeas, lentils, dried peas & beans] are also low in methionine. Soy is a good source but it would require consuming several servings of soy per day to get what you could from small amounts of animal foods. Most vegans rely on fortified vegan protein powders and shakes to get the methionine they need.
Leucine: Leucine is a unique essential amino acid. Leucine is one of the 3 branched chain amino acids [pictured above] that play a vital role in muscle protein synthesis, repair and maintenance. The latest & best research shows that to reap the benefits that protein has to offer on maintaining muscle mass, especially as we age, we need to get about 10 g of leucine at each meal which is easily accomplished when a variety of proteins are eat together, both plant and animal [hint for a total protein content of 30 g per meal]. The reality is, animal foods are abundant in leucine which means they can deliver lots of leucine on their own or, if eaten in smaller serving sizes, can bump up the modest amounts of leucine in plant foods. Manufacturers of vegan foods like meal replacements & protein powders know this which is why many have added extra branched chain amino acids to their products so that they resemble & approximate animal based foods and protein powders – go figure.
To be clear on my bias, it is my personal and professional opinion, that vegan diets are not the best for human health. Whereas vegetarian diets that include some kind of animal product like fish, egg or dairy, will easily eliminate the nutritional concerns of a vegan diet, vegan diets need to be given extra care and attention. There’s a reason why there’s never been a vegan society/culture in human history unless I am proven otherwise. That’s because precious sources of food, like animals, would have never been passed up. Even Buddhist monks will eat eggs and dairy. As such, the human body evolved within the context of different diets that provided the unique nutrients found in animal foods allowing the human race to thrive. Of course my role as a dietitian and nutritionist would be to help anyone who wants to follow a vegan diet ensure they are getting the nutrients they need in a manner that fits their philosophy.
I don’t believe that it’s possible in the long term to meet our nutrient needs in a way that propels us to optimal health [well into our 70s and beyond] on a vegan diet without the use supplements. The reality is, vegans struggle to get enough B12, zinc, iron, calcium, choline, vitamins A & D3, and omega-3 fats EPA and DHA [not to mention choline and the others] in amounts that are easily absorbed by the body. This is especially true for children.