(Healthline) – Vegan and vegetarian diets are both very healthy ways of eating.
They have been linked to multiple health benefits and a lower risk of excess weight, heart disease, and even some types of cancer.
However, a few nutrients are either difficult or impossible to get in adequate amounts from plant foods. Therefore, it’s very important to be aware and supplement your diet with them to maintain health or physical performance.
Here are 7 nutrients commonly lacking in vegetarian and vegan diets.
Vitamin B12 is an essential nutrient that’s almost exclusively found in animal-sourced foods, such as fish, meat, dairy products, and eggs (1Trusted Source).
Also known as cobalamin, it’s a water-soluble nutrient involved in developing red blood cells and maintaining nerves and normal brain function.
Studies have shown that without supplements or enriched foods, vegetarians are at a high risk of vitamin B12 deficiency (2Trusted Source).
Lacto-ovo-vegetarians can get adequate amounts of this nutrient from dairy products and eggs, but this is much more challenging for vegans (3).
Vegans who don’t take supplements are therefore at a higher risk of vitamin B12 deficiency than vegetarians (4Trusted Source, 5Trusted Source, 6Trusted Source, 7Trusted Source).
The symptoms and risks associated with vitamin B12 deficiency include:
weakness, fatigue (8Trusted Source)
impaired brain function (9Trusted Source)
neurological disorders (10Trusted Source)
psychiatric disorders (11Trusted Source)
neurological disorders in babies of breastfeeding mothers (12Trusted Source)
megaloblastic anemia (13Trusted Source)
possible links to Alzheimer’s disease (14)
possible links to heart disease (15Trusted Source)
To get sufficient amounts of vitamin B12, those following a vegan diet must get vitamin B12 by taking supplements or eating food that has been fortified with this nutrient.
These include enriched yeast extracts, soy products, breakfast cereals, bread, and meat substitutes (3, 16Trusted Source).
In addition, a few plant foods naturally contain trace amounts of bioactive vitamin B12, including:
nori seaweed, a type of marine algae (17Trusted Source, 18Trusted Source, 19Trusted Source, 20Trusted Source)
tempeh, a fermented soy product (21, 22Trusted Source)
Nori seaweed is considered the most suitable source of biologically available vitamin B12 for vegans, though it doesn’t provide a sufficient amount on its own (23Trusted Source).
Keep in mind that raw or freeze-dried nori may be better than conventionally dried types, as some of the vitamin B12 is destroyed during the drying process (19Trusted Source, 24Trusted Source, 25Trusted Source).
However, those are not considered to be sufficient sources of dietary vitamin B12 and do not provide the daily need.
Another plant food often claimed to contain vitamin B12 is spirulina. However, it offers only pseudovitamin B12, which is not biologically available. For this reason, it’s unsuitable as a source of this vitamin (26Trusted Source).
If you want to boost your vitamin B12 intake, you can buy vegan-friendly supplements locally or online.
Vitamin B12 is only found in animal and fortified foods, as well as in small amounts in certain types of seaweed. People following a vegan diet should supplement with a vegan vitamin B12 supplement.
Creatine is a molecule found in animal foods.
Most of it is stored in muscles but significant amounts are also concentrated in the brain.
It functions as an easily accessible energy reserve for muscle cells, giving them greater strength and endurance (27Trusted Source).
For this reason, it’s one of the world’s most popular supplements for muscle building.
Studies show that creatine supplements can increase both muscle mass and strength (28Trusted Source).
Creatine is not essential in your diet, as it can be produced by your liver. However, studies have shown that vegetarians tend to have lower amounts of creatine in their muscles (29Trusted Source).
One study placed people on a lacto-ovo-vegetarian diet for 26 days and found that doing so caused a significant decrease in their muscle creatine levels (30Trusted Source).
Because creatine is only naturally found in animal tissue, vegetarians and vegans can only get it from supplements.
For vegetarians, creatine supplements may have significant benefits, including:
improvements in physical performance (29Trusted Source)
improvements in brain function, such as memory (31Trusted Source, 32Trusted Source)
Some of these effects are stronger in people on a vegetarian diet than in meat eaters. For instance, vegetarians taking creatine supplements may experience significant improvements in brain function while meat eaters see no difference (31Trusted Source).
This may be attributed to the meat eaters already having higher levels of creatine in their muscles as a result of their diet.
You can purchase vegan-friendly creatine supplements locally or online.
Creatine is a bioactive compound that is lacking in plant-based diets. It plays an important role in brain and muscle function.
Carnosine is an antioxidant that’s concentrated in the muscles and brain of humans and animals (33Trusted Source, 34Trusted Source).
It’s very important for muscle function, and high levels of carnosine in muscles are linked to reduced muscle fatigue and improved performance (35Trusted Source, 36Trusted Source, 37Trusted Source, 38Trusted Source).
Carnosine is only found in animal-based foods. However, it’s considered non-essential, as your body can form it from the amino acids histidine and beta-alanine.
Dietary sources of beta-alanine may contribute significantly to muscle levels of carnosine, but the main dietary sources — meat, poultry, and fish — are non-vegetarian.
Subsequently, studies have shown that vegetarians have less carnosine in their muscles than meat eaters (39Trusted Source, 40Trusted Source).
Supplementing with beta-alanine is a great way to increase the levels of carnosine in your muscles, improving endurance and increasing muscle mass (35Trusted Source, 41Trusted Source, 42Trusted Source, 43Trusted Source, 44Trusted Source, 45Trusted Source).
Fortunately, there are multiple vegan beta-alanine supplements available online.
Carnosine is a nutrient only found in animal-derived foods. It’s important for muscle function. Beta-alanine supplements increase the levels of carnosine in muscles.
Vitamin D3 (Cholecalciferol)
Vitamin D is an essential nutrient with many important functions.
Also called the sunshine vitamin, vitamin D doesn’t have to come from your diet.
Your skin can produce it when it’s exposed to sunlight. However, if your sunlight exposure is limited or you live far from the equator, you must get it from food or supplements.
There are two types of dietary vitamin D — ergocalciferol (D2) found in plants and cholecalciferol (D3) found in animal-based foods.
Of these types, cholecalciferol (D3) increases blood levels of absorbable vitamin D much more efficiently than ergocalciferol (D2) (57Trusted Source, 58Trusted Source, 59Trusted Source).
The best sources of vitamin D3 are fatty fish and egg yolks. Other sources include supplements, cod liver oil, or enriched foods like milk or cereals (60Trusted Source).
As the main dietary sources of vitamin D3 are not plant-based, vegetarians and vegans may be at a higher risk of deficiency, especially during the winter in countries north or south of the equator.
Deficiency in vitamin D is linked to an increased risk of various adverse conditions, including:
osteoporosis, with an increased risk of fractures in older adults (46Trusted Source)
cancer (47Trusted Source)
heart disease (48Trusted Source, 49Trusted Source)
multiple sclerosis (50Trusted Source)
depression (51Trusted Source)
impaired brain function (52Trusted Source)
muscle wasting and reduced strength, especially in older people (53Trusted Source, 54Trusted Source, 55Trusted Source, 56Trusted Source)
Vegan vitamin D3 supplements made from lichen are also available (61Trusted Source).
Cholecalciferol (D3) is a type of vitamin D found in animal-sourced foods, especially fatty fish, and it’s more effective at raising blood levels of vitamin D than the plant form of vitamin D (D2). Vegan vitamin D3 supplements can be purchased online.
Docosahexaenoic acid (DHA)
Docosahexaenoic acid (DHA) is an essential omega-3 fatty acid that’s important for normal brain development and function (62Trusted Source).
Deficiency in DHA can have adverse effects on mental health and brain function, especially in children (63Trusted Source, 64Trusted Source).
In addition, inadequate DHA intake in pregnant women may adversely affect fetal brain development (65Trusted Source).
It’s mainly found in fatty fish, fish oil, and certain types of microalgae.
In your body, DHA can also be made from the omega-3 fatty acid ALA, which is found in high amounts in flax seeds, chia seeds, and walnuts (66Trusted Source, 67, 68Trusted Source).
However, the conversion of ALA to DHA is very inefficient and may not increase blood levels of DHA sufficiently (69Trusted Source, 70Trusted Source).
For this reason, vegetarians and vegans often have lower levels of DHA than meat eaters (71Trusted Source, 72Trusted Source, 73Trusted Source).
Vegans can get this important fatty acid by taking supplements in the form of algal oil, which is made from certain microalgae (74Trusted Source, 75Trusted Source, 76Trusted Source).
These supplements are available in specialty stores and online.
Docosahexaenoic acid (DHA) is an essential omega-3 fatty acid found in fatty fish and fish oil. It’s also present in microalgae, which are a suitable dietary source for vegetarians and vegans.
Heme iron is a type of iron only found in meat, especially red meat.
It’s much better absorbed than non-heme iron, which is commonly found in plant foods (77Trusted Source).
Heme iron also improves your absorption of non-heme iron from plant foods. This phenomenon is not entirely understood but is called the “meat factor.”
Non-heme iron is poorly absorbed, and its absorption can be limited further by antinutrients that are also present in plant foods, such as phytic acid.
Unlike non-heme iron, the absorption of heme iron is not affected by the presence of antinutrients.
For this reason, vegetarians and vegans — especially women and people on raw food diets — are more prone to anemia than meat eaters (5Trusted Source, 78Trusted Source).
However, iron deficiency is easy to avoid on a well-planned vegan diet that contains plenty of non-heme iron.
Meat, especially red meat, contains a type of iron called heme iron, which is much better absorbed than non-heme iron from plant foods.
Taurine is a sulfur compound found in various body tissues, including your brain, heart, and kidneys (79Trusted Source).
While its bodily function is not entirely clear, it appears to play a role in muscle function, bile salt formation, and antioxidant defenses (80Trusted Source, 81, 82Trusted Source, 83Trusted Source).
Taurine is only found in animal-sourced foods, such as fish, seafood, meat, poultry, and dairy products (84Trusted Source).
Subsequently, studies have shown that vegans have much lower levels of taurine than meat eaters (85Trusted Source, 86Trusted Source).
It’s not considered essential in the diet, as your body produces small amounts. Still, dietary taurine may play a role in maintaining your body’s taurine levels.
Synthetic taurine supplements are widely available and suitable for vegetarians and vegans.
Taurine is a sulfur compound that has several functions in your body. It’s only found naturally in animal-based foods but also available in synthetic supplement form.
The bottom line
Well-planned vegetarian and vegan diets are very healthy.
Unfortunately, a few nutrients are impossible or difficult to get from commonly consumed plant foods.
If you plan to eliminate animal-sourced foods from your diet, make sure to keep those nutrients in mind, and take dietary supplements to make sure that you’re getting everything your body needs.