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 foods regardless of how often, then you’re not a vegetarian; it’s about 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 that contain animal foods are necessarily healthier but study after study shows that vegetarian and vegan diets 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 with vegan diets
One of the concerns with vegan diets is meeting your recommended intake of vitamins and minerals. This is due to the simple fact that nutrients are concentrated more in animal foods and you get a lot more of them on a per-serving basis. This is well illustrated with sockeye salmon which packs a ton of nutrients in a 212 g serving.
Not only that, but the nutrients in animal foods are also absorbed more efficiently from animal foods.
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 are 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. (3, 4).
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 refer to those from animal foods (fish, seafood & fortified eggs) interchangeably with those that are found in concentrated amounts in certain plant foods [walnuts, canola, chia, soy, flaxseeds, and chia seeds].
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. In fact, the benefits of long change omega-3s are very apparent when you consider their role in the omega-3 to omega-6 ratio and its impact on health.
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 is why there’s been 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.
Vitamins A and D
Straight up. 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 relatively small (5) and not everyone does it to the same degree.
It’s estimated that 1/3 of us are poor converters. (This can be assessed using MyBlueprint, a genetic test to screen for genetically-related nutritional risk factors: see their MyBlueprint Sample Report. This test will show you if you’re one of the 30% or so of the population that has a genetic limitation in converting beta-carotene into vitamin A.
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. The estimated equivalency [conversion] ratio for beta-carotene to vitamin A from plants ranges from 3.8-28.1…that’s a lot of carotene that’s needed to make enough vitamin A.
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 (6) although both vegans and omnivores don’t get enough of this critical vitamin that’s a different story.
But that’s not all..
Choline
A cousin to the B vitamins, choline is a very underappreciated nutrient. See my full post on choline. 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’s absorbed better too.
Best food sources are liver, egg, fish, milk, turkey, chicken & seafood. As is, most miss the mark when it comes to getting the recommended intake of choline which is 425 mg/day for women 19 years of age and older, and 550 mg/day for men of the same age category.
Choline. An Essential Nutrient for Public Health
Choline is needed for cognition, memory consolidation, learning, muscle coordination, and for fetal brain development. Choline is also the building block of the main structural molecule of your cells; phospholipids. Choline is needed for the production of acetylcholine, an important neurotransmitter and choline plays a role in preventing fatty liver disease.
When it comes to a healthy pregnancy, choline, along with the omega-3 fat DHA, is crucial for women and their growing babies.
Creatine & carnosine
Creatine is not just for bodybuilders, 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 (7, 8 9). Carnosine is a 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 (10).
Methionine
Methionine is an essential amino acid 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. It’s one of the 3 branched-chain amino acids [pictured above] that plays 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 eaten together, both plant and animal [hint for 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.
Glycine
Glycine is 1 of 20 amino acids that make up the human body. Under normal healthy conditions, the body can make about 12 of the 20 amino acids on its own either from scratch or by recycling old amino acids as part of the normal turnover of the body [a.k.a. they’re considered ‘non-essential‘]; cells and tissues are constantly being broken down and rebuilt.
The other 8 amino acids are called ‘essential‘ and therefore must be obtained from the diet. Glycine has long been assumed to be a conditionally essential amino acid; that we need more of it only during times of illness and stress where supply cannot meet demand but new research suggests otherwise.
It’s estimated that the majority of glycine, 85% of it, comes from the conversion of another amino acid called serine; this provides the body with about 3 g per day with a diet providing about another 1.5 to 3 g.
Taking this all together, the body has about 4.5 to 6 g of glycine that’s available for metabolic demands, not the least of which is collagen production, but here’s the rub – a 70 kg, or 153 pounds, needs about 15 g of glycine daily, leaving a deficit of about 8.5 to 10 g/day, give or take. A person weighing less will have less of a deficit but a deficit and still ‘be in the red’.
Read more about glycine in my other post Glycine. Anti-aging clout from this humble amino acid?
Final thoughts
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 & 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.
Doug Cook RDN is a Toronto dietitian and functional nutritionist with a focus on digestive, gut, mental health. Follow me on Facebook, Instagram and Twitter.