For anyone currently following (or considering) a vegan diet, it is crucial to be aware of specific nutrient shortfalls of the diet.
While many people choose to be vegan for ethical reasons, there are many myths about vegan diets and animal foods.
Firstly, animal foods have long been a source of nutrients in human diets, and this includes some unique nutrients not found elsewhere. We must consider what happens when we remove these foods from the diet.
In this article, we examine some specific nutrients that vegan diets don’t provide.
Following this, we also look at some nutrients that can be more difficult to consume in sufficient amounts on a vegan diet.
Nutrients That Vegan Diets Don’t Provide
Vegan diets do not provide the following nutrients, and we can only find them in animal foods.
Why are they important? And can we adequately replace them?
1) Vitamin B12
Vitamin B12, otherwise known as cobalamin, is an essential water-soluble vitamin with a wide range of important functions.
Among these functions, vitamin B12 is vital for forming and maintaining healthy red blood cells and DNA (1).
- Megaloblastic anemia
- Nerve problems
- Stomach inflammation
- Neural tube defects (NTD) during pregnancy
We can only naturally find this vitamin in animal foods such as meat, eggs, fish, and other seafood.
Is Vitamin B12 Essential?
Yes, vitamin B12 is essential for human health, and developing a deficiency in this nutrient can be extremely dangerous.
Unfortunately, reports show that the average depletion and deficiency rates for vitamin B12 among vegetarian dieters are (5);
- Children: 25-86%
- Adolescents: 21-41%
- Pregnant women: 62%
- Elderly: 11-90%
The research also shows that these deficiency rates are higher in vegans.
Can Vegan Diets Provide Vitamin B12?
Vegans may get vitamin B12 from two sources;
- Fortified foods (e.g., breakfast cereals and certain vegan products)
However, it is worth noting that fortified foods tend to be overly processed compared to whole food options.
As a result, it is a smart idea for anyone on a vegan diet to ensure they get sufficient B12 from supplements.
2) Retinol: Pre-formed (and Bioavailable) Vitamin A
Vitamin A is an essential fat-soluble vitamin that is available in two forms – retinol and carotenoids. This important nutrient plays a key role in immune health and red blood cell production (6).
However, some vegan dieters may not realize the difference between beta-carotene and retinol.
Firstly, beta-carotene, found in plant foods, is not vitamin A.
When we consume beta-carotene, it (may) convert to vitamin A inside the body, but the conversation rates are generally poor (7).
In contrast, retinol, found in animal foods, is pre-formed vitamin A in its active state, meaning that the body can use it without relying on any conversion.
The Difference In Vitamin A Bioavailability
To make the difference more clear between retinol and beta-carotene, the Food and Nutrition Board at the Institute of Medicine of the National Academies created a new way to measure vitamin A in food called ‘retinol activity equivalents’ (RAE) (7).
This new measurement helps individuals to better understand the relative bioavailability of vitamin A from different sources.
According to the new measurement system, the difference between beta-carotene and retinol is (7);
- 1 IU of retinol = 0.3 mcg RAE vitamin A
- 1 IU of beta-carotene from food = 0.05 mcg RAE vitamin A
In other words, according to the new measurement, retinol is approximately 6x more bioavailable than beta-carotene as a source of vitamin A.
Additionally, some individuals have certain genetic variations that mean they have lower amounts of a gene called BCO1.
BCO1 is otherwise known as beta-carotene oxygenase 1, and it is responsible for the metabolism of beta-carotene into vitamin A (8).
Is Vitamin A (As Retinol) Essential?
Vitamin A is an essential nutrient, but we can get it from retinol or beta-carotene.
Retinol is not essential.
Can Vegan Diets Provide Vitamin A?
Many vegan dieters have perfectly fine blood levels of vitamin A from consuming beta-carotene-rich foods.
However, it may be worth testing vitamin A levels to make sure they are adequate.
For any vegan dieters with low levels of vitamin A, supplementing with retinol could be a consideration.
Anyone with any confusion or queries on this topic should speak to their doctor for personalized advice.
3) Vitamin D3
Vitamin D is more than just a vitamin, and it is a hormone that plays a significant role in the immune system (9).
This vitamin also regulates the amount of calcium in our blood, thereby having an important influence on bone health (10).
Furthermore, research shows that adequate vitamin D levels may potentially lower the risk for chronic diseases such as cancer, type 2 diabetes, and cardiovascular disease (11).
Is Vitamin D Essential?
Vitamin D is an essential vitamin that we need to consume in sufficient quantities.
On this note, low blood levels of vitamin D may increase the risk of depression, bone loss, and a wide variety of chronic diseases (12).
Can Vegan Diets Provide Vitamin D3?
That said, the best source of vitamin D is sunshine, and everybody can get sun regardless of their diet.
For this reason, vegans can easily get sufficient vitamin D if they get enough sunlight.
However, for vegans who live in cold and dark places or those who get little sunshine, it may be worth testing vitamin D levels and considering a supplement.
Among its various roles, creatine provides energy for muscular contraction.
Creatine is a compound that we can only find in animal foods such as red meat, poultry, and fish (16).
However, the human body synthesizes and produces its own creatine through the amino acids glycine, arginine, and methionine. As a result, we do not need to obtain it from dietary sources (17).
That said, research shows that dietary creatine intake offers some unique benefits. For instance, a higher dietary intake of creatine can improve sports performance (18).
Research also shows that vegan (and vegetarian) diets promote lower muscle creatine stores (19).
Is Creatine Essential?
Creatine is not essential, and a lower dietary intake of creatine is not a significant health concern.
Can Vegan Diets Provide Creatine?
Since vegan diets restrict the consumption of all animal foods, they cannot provide dietary creatine.
For this reason, any vegan dieters who take sports performance seriously may wish to consider creatine supplementation.
However, it is not a necessary consideration for general health.
5) Heme Iron
Iron is an essential mineral involved in forming hemoglobin and oxygen transportation (20).
There are two different forms of dietary iron, and these are;
- Heme iron: highly bioavailable, and found in animal foods
- Non-heme iron: found in plant foods, and it has lower bioavailability
Researchers estimate the bioavailability of iron from omnivore diets is around 14-18%. However, for vegetarian diets, this falls to 5-12% (20).
For this reason, the reference daily intake (RDI) for iron in vegans is 1.8x higher than for people consuming a diet including animal foods (21).
Is Heme Iron Essential?
No, heme iron is not essential, and we can get iron from non-heme sources found in plant foods.
However, it is worth remembering that heme iron is more bioavailable than non-heme sources of the mineral.
Can Vegan Diets Provide Heme Iron?
No, vegan diets contain no heme iron.
While this makes it more difficult to consume sufficient iron, it is possible to maintain regular iron stores providing the diet contains enough non-heme iron.
The highest food sources of non-heme iron include;
- Cocoa/dark chocolate
- Leafy greens such as spinach
- Soy-based foods such as natto and tempeh
Taurine is a non-essential amino acid, and it is the primary amino acid found in the human body.
We do not require taurine from our diet because our body can produce it naturally from the amino acids cysteine and methionine (22).
However, despite its non-essential classification, there may be several benefits from dietary taurine intake.
Furthermore, randomized controlled trials show that taurine supplementation can reduce blood pressure and lower cardiovascular risk (26).
Is Taurine Essential?
Taurine is not essential, and we do not require it from our diet.
However, a higher dietary intake may have several desirable health benefits.
Can Vegan Diets Provide Taurine?
No, vegan diets do not provide taurine, which is only available from animal foods.
For this reason, it is a compound that may be worthy of supplementing.
Carnosine is a dipeptide molecule composed of the amino acids alanine and histidine.
Once again, our body can produce this compound, so it is not essential that we get it from our diet.
However, there is evidence that consuming it from our diet may have benefits.
For instance, recent systematic reviews on carnosine show that the compound has anti-glycating properties. In other words, it may reduce the formation of AGES (advanced glycation end products) in the body (29).
A meta-analysis of randomized controlled trials shows that diets low in AGES improves markers of cardiovascular health (30).
Is Carnosine Essential?
No, it is not essential that we consume pre-formed carnosine as part of our diet.
However, doing so may have benefits.
Can Vegan Diets Provide Carnosine?
Vegan diets do not provide carnosine, which is only found in animal foods.
There is not a substantial amount of research available on this compound, but research shows vegetarians have a 26% lower blood concentration of carnosine than omnivores do (31).
Again, carnosine supplementation could change this, so it may be worth considering.
Nutrients That Are Difficult To Get On Vegan Diets
Obtaining the following nutrients from vegan diets is possible. However, they are more difficult to get than from mixed omnivore diets.
DHA/EPA are the most bioavailable form of omega-3, and their absorption rate is much better than ALA omega-3 (found in seeds/nuts/vegetables) (32).
However, algae is a vegan source of DHA/EPA.
L-carnitine is an interesting compound that has wide-ranging effects on the body (33).
Contrary to popular belief, both animal and plant foods can be a source of this compound. However, the amounts present in plant foods are unsubstantial.
Animal foods are an excellent source of all B vitamins.
While vegan diets can’t provide B12, they can offer sufficient amounts of the other B vitamins if the diet is well-formulated.
Choline is an essential vitamin-like compound that has several benefits for our health (34).
Among these, it is important for liver health and preventing fatty liver disease (35).
Choline can be found in many foods, but plant foods offer insignificant amounts.
Zinc is an essential mineral, and animal foods typically provide it in large amounts.
It is possible to get sufficient zinc from a well-formulated vegan diet, but supplementation could be worth considering.
Vitamin K1, mainly found in vegetables, has poor bioavailability and it also has a very limited half-life within the body (36).
MK-4 is available from animal foods and supplements, while the best source of MK-7 is fermented soy foods like natto.
As shown in this article, there are many nutrients and beneficial compounds not available from vegan diets.
There are also several nutrients that can be difficult to consume in sufficient quantities.
For people who have decided to become vegan, each of these nutrients is worth consideration when planning the diet.
It is also worth noting that several plant-based meat products, such as the Awesome Burger, lack a wide range of nutrients.
As always, nutrient-dense whole foods should be the focus of any healthy diet.