Written by Atli Arnarson BSc, PhD — Medically reviewed by Kim Chin, RD, Nutrition — Updated on June 9, 2021
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Vegan and vegetarian diets are both very healthy ways of eating.
They’ve 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 alone. That’s why it’s very important to be aware them and supplement your diet to maintain health or physical performance.
Here are 7 nutrients commonly lacking in vegetarian and vegan diets.
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Vitamin B12 is an essential nutrient that’s almost exclusively found in animal-sourced foods, such as fish, meat, dairy products, and eggs (1).
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 (2).
Lacto-ovo-vegetarians can get adequate amounts of this nutrient from dairy products and eggs, but this is much more challenging for vegans (3).
So, vegans who don’t take supplements are at a higher risk of vitamin B12 deficiency than vegetarians (4, 5, 6, 7).
The symptoms and risks associated with vitamin B12 deficiency include:
To get sufficient amounts of vitamin B12, people following a vegan diet must take supplements or eat food that has been fortified with this nutrient.
These foods include (3, 16):
enriched yeast extractssoy productsbreakfast cerealsbreadmeat substitutes
In addition, a few plant foods naturally contain trace amounts of bioactive vitamin B12, including:
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 (23).
Keep in mind that raw or freeze-dried nori may be better than conventionally dried types. This is because some of the vitamin B12 is destroyed during the drying process (19, 24, 25).
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, spirulina offers only pseudovitamin B12, which is not biologically available (meaning it can’t be absorbed by the body). For this reason, it’s unsuitable as a source of this vitamin (26).
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 your muscles but significant amounts are also concentrated in your brain.
It functions as an easily accessible energy reserve for muscle cells, giving them greater strength and endurance (27).
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 (28).
Creatine is not essential in your diet, since it can be produced by your liver. However, studies have shown that vegetarians tend to have lower amounts of creatine in their muscles (29).
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 (30).
Because creatine is naturally found in animal tissue, vegetarians and vegans can get it only from supplements.
For vegetarians, creatine supplements may have significant benefits, including:
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 people who eat meat see no difference (31).
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’s 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 (33, 34).
It’s very important for muscle function, and high levels of carnosine in muscles are linked to reduced muscle fatigue and improved performance (35, 36, 37, 38).
Carnosine is only found in animal-based foods. However, it’s considered nonessential, since 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 nonvegetarian.
Studies have shown that vegetarians have less carnosine in their muscles than meat eaters (39, 40).
Supplementing with beta-alanine is a great way to increase the levels of carnosine in your muscles, improving endurance and increasing muscle mass (35, 41, 42, 43, 44, 45).
There are multiple vegan beta-alanine supplements available online.
Carnosine is a nutrient found only in animal-derived foods. It’s important for muscle function. Beta-alanine supplements increase the levels of carnosine in muscles.
Vitamin D is an essential nutrient with many important functions. Also called the sunshine vitamin, it doesn’t have to come from your diet.
Your skin can produce vitamin D 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 plantscholecalciferol (D3), found in animal-based foods
Of these types, cholecalciferol (D3) increases blood levels of absorbable vitamin D much more efficiently than ergocalciferol (D2) (57, 58, 59).
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 (60).
Since 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:
Vegan vitamin D3 supplements made from lichen are also available (61).
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.
DHA is an essential omega-3 fatty acid that’s important for normal brain development and function (62).
Deficiency in DHA can have adverse effects on mental health and brain function, especially in children (63, 64). In addition, inadequate DHA intake in pregnant women may adversely affect fetal brain development (65).
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 flaxseeds, chia seeds, and walnuts (66, 67, 68).
However, the conversion of ALA to DHA is very inefficient and may not increase blood levels of DHA sufficiently (69, 70). For this reason, vegetarians and vegans often have lower levels of DHA than meat eaters (71, 72, 73).
Vegans can get this important fatty acid by taking supplements in the form of algal oil, which is made from certain microalgae (74, 75, 76).
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 found only in meat, especially red meat. It’s much better absorbed than non-heme iron, which is commonly found in plant foods (77).
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. Its absorption can be limited further by anti-nutrients 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 females and people on raw food diets — are more prone to anemia than meat eaters (5, 78).
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 (79).
While its bodily function is not entirely clear, it appears to play a role in muscle function, bile salt formation, and antioxidant defenses (80, 81, 82, 83).
Taurine is found only in animal-sourced foods, such as fish, seafood, meat, poultry, and dairy products (84).
Subsequently, studies have shown that vegans have lower levels of taurine than meat eaters (85, 86).
Taurine isn’t considered essential in the diet, since 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 found naturally in only animal-based foods but is also available in synthetic supplement form.