This article reviews 7 nutrients that are difficult or impossible to get in adequate amounts from commonly consumed plant foods.

All of these nutrients are available to vegetarians and vegans in supplements.

The purpose of this article is not to criticize plant-based diets or encourage meat eating. Plants contain many healthy nutrients that are lacking in meat-based diets.

The aim is to help vegetarians and vegans identify those nutrients with which they may need to supplement to maintain optimal health or physical performance in sports.

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Vitamin B12 is an essential nutrient found in almost no plant foods.

Also known as cobalamin, it’s a water-soluble nutrient involved in developing red blood cells and maintaining nerves and normal brain function.

Without supplements or enriched foods, vegetarians are at a high risk of vitamin B12 deficiency (1).

It’s mainly found in animal-sourced foods, such as fish, meat, dairy products, and eggs (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).

For this reason, 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 deficiency include:

  • weakness, fatigue (8)
  • impaired brain function (9)
  • neurological disorders (10)
  • psychiatric disorders (11)
  • neurological disorders in babies of breastfeeding mothers (12)
  • megaloblastic anemia (13)
  • possible links to Alzheimer’s disease (14)
  • possible links to heart disease (15)

Vegans 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, 16).

In addition, a few plant foods naturally contain trace amounts of bioactive vitamin B12, including:

  • nori seaweed, a type of marine algae (17, 18, 19, 20)
  • tempeh, a fermented soy product (21, 22)

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, as some of the vitamin B12 is destroyed during the drying process (19, 24, 25).

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 (26).

If you want to boost your vitamin B12 intake, you can buy vegan-friendly supplements locally or online.

SUMMARY Vitamin B12 is only found in animal foods and certain types of seaweed. Vegans can get vitamin B12 by taking supplements, eating enriched foods, or eating nori seaweed.

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 (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, as it can be produced by your liver. However, vegetarians have lower amounts of creatine in their muscles (29).

For example, placing people on a lacto-ovo-vegetarian diet for 26 days caused a significant decrease in muscle creatine (30).

Because creatine is not found in any plant foods, vegetarians and vegans can only get it from supplements.

For vegetarians, creatine supplements may have significant benefits. These include:

  • improvements in physical performance (29)
  • improvements in brain function (31, 32)

Many of these effects are stronger in vegetarians than meat eaters. For instance, vegetarians taking creatine supplements may experience significant improvements in brain function while meat eaters see no difference (31).

You can purchase vegan-friendly creatine supplements locally or online.

SUMMARY 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 (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 non-essential, as your body can form it from the amino acids histidine and beta-alanine.

Dietary sources of beta-alanine, such as meat or fish, may also contribute significantly to muscle levels of carnosine.

Vegetarians have less carnosine in their muscles than meat eaters (39, 40).

Supplementing with beta-alanine increases the levels of carnosine in muscles, improving endurance and increasing muscle mass (35, 41, 42, 43, 44, 45).

Vegan beta-alanine supplements are available online.

SUMMARY Carnosine is a nutrient only found in animal-derived foods. It’s important for muscle function. Beta-alanine supplements are effective at increasing the levels of carnosine in muscles.

Vitamin D is an essential nutrient with many important functions.

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 (46)
  • cancer (47)
  • heart disease (48, 49)
  • multiple sclerosis (50)
  • depression (51)
  • impaired brain function (52)
  • muscle wasting and reduced strength, especially in older people (53, 54, 55, 56)

Osteoporosis and rickets are the best-known effects of vitamin D deficiency. Whether the deficiency contributes to the other conditions or is just associated with them is less clear.

Also called the sunshine vitamin, vitamin D doesn’t have to come from your diet.

Your skin can produce it when it is exposed to sunlight. However, if your sunlight exposure is limited, you have to 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 increases blood levels of bioactive vitamin D much more efficiently than ergocalciferol (57, 58, 59).

The best sources of cholecalciferol are fatty fish and egg yolks. Other sources include supplements, cod liver oil, or enriched foods like milk or cereals (60).

Vegan vitamin D3 supplements made from lichen are also available (61).

SUMMARY Cholecalciferol (D3) is a type of vitamin D found in animal-sourced foods, especially fatty fish. It’s much more effective than the plant form of vitamin D, ergocalciferol (D2).

Docosahexaenoic acid (DHA) is an essential omega-3 fatty acid.

It’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 brain development in the child (65).

It’s mainly found in fatty fish and fish oil but also in 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 inefficient (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.

SUMMARY 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 found in plant foods (77).

Not only is heme iron well absorbed, it also improves your absorption of non-heme iron from plant foods. This phenomenon is not entirely understood and is called the “meat factor.”

Unlike non-heme iron, heme iron is not affected by antinutrients, such as phytic acid, often found in plant foods.

For this reason, vegetarians and vegans — especially women and people on macrobiotic 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.

SUMMARY 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).

The bodily function of taurine is not entirely clear.

However, it appears to play a role in muscle function, bile salt formation, and your body’s antioxidant defenses (80, 81, 82, 83).

Supplementing with taurine may have various benefits for heart health, such as lowering cholesterol and blood pressure (84, 85, 86, 87, 88).

Taurine is only found in animal-sourced foods, such as fish, seafood, meat, poultry, and dairy products (89).

It’s not essential in the diet, as your body produces small amounts. Still, dietary taurine may play a role in maintaining your body’s taurine levels.

Levels of taurine are significantly lower in vegans than in meat eaters (90, 91).

Synthetic taurine supplements are widely available and suitable for vegetarians and vegans.

SUMMARY 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.

Nutritionally balanced vegetarian and vegan diets are very healthy.

However, a few nutrients are impossible or difficult to get from commonly consumed plant foods.

If you plan to completely eliminate animal-sourced foods, plan your diet, take dietary supplements, and make sure that you’re getting everything your body needs.