Common Nutritional Concerns for Vegetarians

Being a healthy vegetarian is the goal, it’s not about just avoiding animal products. However, even when you are eating an optimal vegetarian diet, there are still some common nutritional concerns that you should be aware of. A vegetarian diet need not be deficient in nutrients. However, the more foods that are eliminated from the diet, the greater the risk of deficiency. Below are some of the most common pitfalls associated with vegetarian diets.


Protein deficiency

You can avoid this pitfall by consuming enough total calories from a wide variety of nutritious plant foods. Appropriate mixtures of plant foods in the diet have been shown to be equivalent to animal protein in quality, meaning they supply equivalent amounts of essential amino acids.1It is important to obtain adequate amounts of protein in the diet because without sufficient amounts of certain amino acids, the body can develop symptoms ranging from immune system and liver dysfunction to sleep and weight troubles.2 Protein deficiency: add to the end: See Vegetarianism and Protein page for a more detailed conversation about protein.


Carbohydrate excess

Some vegetarians, like many Americans, eat mostly carbohydrates and become quite addicted to sweets. It is very easy for vegetarians to consume too many carbohydrates because carbs are abundant in grains, flours, legumes, fruits, and starchy vegetables (e.g. potatoes, winter squash, peas, and corn). Low-fat, high-carb diets upset the balance within the human body by over-stimulating insulin production, in turn causing a cascade of hormone imbalances. Complex carbohydrates (found in whole grains, vegetables, and legumes) may be absorbed into the bloodstream more slowly than simple carbohydrates (found in sugars and refined flour) because they are rich in fiber.

An increase in blood sugar caused by carbohydrate consumption (glucose) stimulates the pancreas to release insulin. Insulin “unlocks” the cell doors to sugar, allowing sugar to be burned for energy. A diet that is high in refined carbohydrates contributes to a condition called “insulin-resistance.” 3 In insulin resistance, our insulin signaling is impaired and our cells have difficulty taking in the glucose in our blood.4 When this happens, sugar in the bloodstream gets stored as fat around the mid-section rather than being burned as energy. Possible consequences of prolonged high insulin levels in the body include depression, excessive weight gain, heartburn and other gastrointestinal problems, cardiovascular issues, high blood pressure, high cholesterol and triglyceride levels, type-2 diabetes, infertility, insomnia and fatigue, and headaches.


Vitamin B12 (cobalamin) deficiency

Of all the micronutrients, B12 is the one that vegetarians should be most concerned about. Though B12 deficiency can be caused by a variety of factors, it is most commonly caused by avoidance of animal based foods.5 Vegans who do not supplement their diet with vitamin B12 will eventually develop a type of anemia (megaloblastic) that results in irreversible damage to the nervous system. Most, if not all, vegans have impaired B12 metabolism6 and every study of vegan groups have demonstrated low vitamin B12 concentrations in the majority of individuals.

Vitamin B12 is produced by bacteria, especially strains that live in soil. When animals ingest these bacteria through plant consumption, B12 is stored in their flesh. Therefore, the best sources of vitamin B12 are animal flesh foods. Though forms of B12 exist in vegetable foods such as bacterially fermented soy foods (e.g. tempeh), brewer’s yeast, and some algae and seaweeds, it is in the form of a noncobalamin analogue, which is not bioavailable.7,8,9,10Therefore, the B12 analogues in plant foods cannot perform the same essential functions that true vitamin B12 does. Studies done on blood levels of B12 showed no change after consuming spirulina and tempeh, clearly indicating no absorption by the body.11 Additionally, consumption of these analogues have been shown to block vitamin B12 metabolism.7 Thus, individuals who rely exclusively on these sources without supplementing are at an increased risk of a B12 deficiency. Furthermore, over-consumption of soy increases the body’s need for B12.12

Some vegetarian authorities claim that B12 is produced by certain fermenting bacteria in the intestines. This may be true, but it is in a form unusable by the body. B12 requires intrinsic factor from the stomach for proper absorption in the ileum. Since the bacterial product does not have intrinsic factor bound to it, it cannot be absorbed.13

Suggested Daily Intake of B12

  • 100-400 mcg daily 12,14 (Total dose including multiple vitamin/mineral).
  • Higher doses can be taken for a variety of purposes.

Foods rich in B-12 (per 3.5 oz. serving)

  • Liver = 104 mcg
  • Sardines = 17 mcg
  • Trout = 5 mcg
  • Salmon = 4 mcg
  • Beef = 1.8 mcg
  • Blue cheese = 1.4 mcg
  • Cottage cheese = 1 mcg


Essential fatty acid insufficiency

Getting the right balance of essential fatty acids (EFAs) may be more difficult in a vegetarian diet than an omnivorous diet. The two EFAs are linoleic acid (LA, omega-6) and alpha linolenic acid (ALA, omega-3). Because the human body cannot synthesize these EFAs from other fats, they must be provided by foods. The body utilizes EFAs as sources of energy, as functional components of cell membranes, and for the production of various compounds in the body such as eicosanoids that either promote or modulate inflammation.15Linoleic acid is found in high amounts in vegetable oils like soy, corn and peanut oil, whereas ALA is found in flaxseeds, walnuts and green leafy vegetables. Due to the abundance of vegetable oils in the modern American diet, the ratio of omega 6 to omega 3 that we take in through diet ranges from 10:1 to 20:1.16 By contrast, the ratio considered optimal for human health is about 2:1 or 1:1 .17,18,19

Two vitally important omega 3s, EPA and DHA, are found exclusively in wild, coldwater fish such as salmon, tuna, trout, sardines and herring. If fish is a part of your diet, consuming these types of fish 3-6 times per week provides an optimal amount of EPA and DHA. If fish is not a part of your diet, you will have a much harder time obtaining the desired amounts of these omega 3s without supplementation.

While the body can make EPA and DHA from ALA found in plant foods, this conversion, particularly from ALA to DHA, is limited in most individuals.20-23Studies show that vegetarians have significantly lower serum levels of DHA than omnivores, who generally obtain their DHA from fish.23 For those vegetarians that avoid fish and other animal products, supplementing with DHA-rich algae (e.g. Neuromins, NOW Vegetarian/Vegan DHA Omega Supreme) is a good way to avoid DHA insufficiency, while supplementing with hemp seed oil or echium seeds (found in Ascenta NutraVege product) is a good way to avoid EPA insufficiency. While hemp seed oil and echium seeds do not contain pre-formed EPA, they do contain the omega-3 stearidonic acid (SA), which is more readily converted to EPA in the body than ALA is. However, adding ALA-rich foods to the diet can also be effective at increasing EPA concentrations, if these foods are added in significant quantities.

For those who wish to increase EPA concentrations in the body by consuming flaxseed oil, research suggests taking up to ten times as much ALA as you would EPA.24 Typically, this means that 7.2 grams of flaxseed oil should equal 1 gram of fish oil.25 The conversion of ALA to EPA is most efficient when intake of vegetable oils and damaged fats (like those found in fried foods and hydrogenated oils) are restricted in the diet.26

Suggested daily intake of EPA/DHA

  • 3 to 6 grams of EPA/DHA (from fish oil) or 1,000 mg of flax oil combined with 100 mg of a seaweed extract.12

EPA/DHA in 100 grams of the following fish:

  • Tuna fish =1.3 grams
  • King Salmon = 1.4 grams
  • Atlantic Salmon = 1.2 grams
  • Pacific Herring = 1.7 grams
  • Anchovy = 1.4 grams
  • Mackerel = 2.5 grams
  • Lake Trout = 1.6 grams
  • Halibut = 0.4 grams
  • Sole = 0.1 grams
  • Cod = 0.3 grams


Vitamin D

Concerns about vitamin D deficiencies in vegetarians and vegans exist because this nutrient, in its full-complex form, is found only in animal fats such as fish liver oils, fatty fish, egg yolk, butter and fortified dairy products.27Plants and fungi contain a form of vitamin D called ergocalciferol, or vitamin D2. However, some studies have shown that D2 is not utilized as well as D3 from animal foods.28 Although vitamin D can be created by our bodies when skin is exposed to sunlight, it is difficult to obtain an optimal amount of vitamin D by brief, intermittent sun exposure.29 Be sure to get your blood levels of vitamin D measured and supplement with anywhere from 1,000 to 5,000 IU of vitamin D per day to avoid insufficiency.30

Suggested Daily Intake of Vitamin D

  • 1000 – 5,000 IU 30 (total intake including multi-vitamin)

Rich food sources of vitamin D:

  • Herring = 765 IU/3 ounces
  • Salmon = 425 IU/ 3 ounces
  • Sardines, canned = 255 IU/ 3 ounces
  • Cod liver oil = 1360 IU/tablespoon
  • Egg = 25 IU (1 large)
  • Butter = 2.8 IU/pat (5 grams)
  • Mushrooms = 12.6 IU/ 1 cup raw, sliced
  • Fortified milk products
  • Milk, 3.25% (whole fat) = 97.6 IU/cup
  • Milk, 1% (low fat) = 127 IU/cup
  • Milk 2 % (reduced fat) = 105 IU/cup
  • Fortified cereals = 40-50 IU/1 cup


Vitamin A

True vitamin A, or retinol, is found only in animal fats and organ meats. Butter, liver, and full-fat dairy foods, especially from pastured cows, and cod liver oil are good sources of vitamin A. Vitamin A is essential in our diets because it enables the body to use proteins and minerals, supports proper vision, enhances the immune system, enables reproduction and fights infections.29,31 Plants contain beta-carotene, a substance that the body can convert into vitamin A if certain conditions are present. Beta-carotene is an important nutritional factor for humans but it is not vitamin A, and therefore does not have the same functions as vitamin A. The conversion from carotene to vitamin A in the intestines can take place only in the presence of bile salts. This means that fat must be eaten with the carotenes to stimulate bile secretion. Additionally, infants and people with hypothyroidism, gall bladder problems, or diabetes either cannot make the conversion, or do so very poorly.31 Regardless, the body’s conversion from beta-carotene to vitamin A is not very efficient. It takes roughly 6 units of carotene to make one unit of vitamin A— meaning a sweet potato (containing about 25,000 units of beta-carotene) can convert into only about 4,000 units of vitamin A (assuming you ate it with fat, are not diabetic, are not an infant, and do not have a thyroid or gall bladder problem).32 The ability of the body to utilize beta-carotene varies with the food and form in which the food is ingested. Light cooking, pureeing, or mashing of vegetables ruptures the cell membranes and therefore makes the carotene more available for absorption in some foods. For example, antioxidant levels increased by more than 34% immediately after carrots were cooked.33The best food sources of beta-carotene are brightly colored fruits and vegetables such as cantaloupe, apricots, red peppers, sweet potatoes, and dark leafy greens.31

Suggested Daily Intake of Vitamin A

  • For males: 5000 IU retinol or 30,000 mcg beta carotene or 60,000 mcg other carotenes34
  • For females: 2,500 IU retinol or 15,000 mcg beta carotene or 30,000 mcg other carotenes34



This is a vitamin-like nutrient related in structure to the B vitamins. L-carnitine is the biologically active form of carnitine. Carnitine can be synthesized by the body in the liver and kidneys. It is important for the transport of fatty acids into the muscles, where they can be burned for energy. It also plays an essential role in transporting substances into the heart, which is a key reason this nutrient supports heart health. Carnitine also supports brain function, works as an antioxidant, and helps detoxify the body. Vegetarians are at particular risk of low carnitine levels for two reasons: first, L-carnitine can be obtained only from animal foods, and second, the synthesis of L-carnitine in the body relies upon the amino acid lysine, which is scarce in the vegetarian diet. Many staple foods for vegetarians (i.e. corn, wheat and rice) have low levels of lysine, and cooking and toasting of these foods destroys lysine entirely.14

Suggested daily intake of L-carnitine

  • 1,500 to 4,000 mg daily34


NOTE: Children and pregnant women.

Lacto-ovo vegetarian diets generally provide adequate nutritional support during pregnancy and lactation. Special attention in obtaining certain nutrients is needed for those following a vegan or macrobiotic diet. These include taking in enough calories, iron status, vitamin B12 intake, calcium and vitamin D intake. Nutritional needs of children and pregnant women on vegetarian diets should be reviewed by a certified nutritionist or other health professional to ensure needs are met. It should be noted that children given low fat diets are at greater risk of developing many growth and health problems. Children need to eat foods that will provide natural fats (saturated, polyunsaturated, etc.), and they need to have enough of their caloric intake as fat so that they grow and develop properly, prevent illness, and are happy and active.

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