Vegetarian diets have enjoyed a surge of popularity in health-conscious people, as well as those who object for ethical reasons to eating animals or animal by-products. A meatless diet can be healthy, but some vegetarians may develop dangerous vitamin deficiencies.
Common Vegetarian Vitamin Deficiencies
There are different vegetarian and semi-vegetarian diets. Some prohibit meat but allow fish (pescatarian), while others exclude meat and fish, yet allow dairy and eggs (lacto ovo vegetarian). Vegans eat no meat or animal by-products whatsoever including eggs, honey, and dairy.
According to an article published in the American Journal of Clinical Nutrition (AJCN), an increased risk of developing vitamin deficiencies occurs when you eliminate animal products from your diet. The risk is higher for vegans than vegetarians who consume dairy or eggs.
The National Institutes of Health (NIH) indicates that vitamin B12, also known as cobalamin, supports proper red blood cell formation, DNA synthesis, and neurological functions. Serious symptoms may occur if you have a vitamin B12 deficiency.
The recommended daily allowance (RDA) of vitamin B12 for adults is 2.4 mcg daily. Good sources of vitamin B12 include fish and shellfish, beef, dairy products, and eggs. Vegetarians who eat eggs and dairy shouldn't have a problem getting enough vitamin B12; however, vegans may struggle. Vegan sources of B12 are fortified cereals, meat substitutes such as veggie burgers or tofu, soy products, and nutritional yeast.
Vitamin D is produced in the body when skin is exposed to sunlight. It's also found in fish, fish oil, and eggs. Vegetarians may experience vitamin D deficiency symptoms.
The RDA for vitamin D is 400 IU (10 mcg) daily. Lack of sunshine, especially during winter months, is a main reason for vitamin D deficiency in vegetarians and non-vegetarians. However, whether you should get vitamin D from the sun is controversial due to the risk of skin cancer. The American Academy of Dermatology recommends people get vitamin D from foods and, if necessary, supplements. According to the NIH, some researchers suggests five to 30 minutes in the sun between 10:00 a.m. and 3:00 p.m. at least twice a week to the face, back, arms, or legs is adequate.
Vegans or vegetarians who don't eat eggs should eat vitamin-fortified products, such as cereals, grains, soy products, orange juice, and rice milk to reach the vitamin D RDA.
Long-Chain Fatty Acids
According to the AJCN article, people who do not eat fish, eggs, and sea vegetables may be deficient in long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), all of which play important roles in cardiovascular, eye, and brain health. Long-chain omega-3 fatty acids are converted into EPA and DHA in the body. Vegetarians and vegans often display lower serum levels of EPA and DHA than non-vegetarians.
The article adds that vegetarians and vegans should be able to get adequate omega-3 fatty acids by eating food rich in alpha-linolenic acid (ALA). Good ALA sources include flax, chia, and hemp.
The NIH states that iron is "necessary for growth, development, normal cellular functioning, and synthesis of some hormones and connective tissue." Iron has two forms -- heme and non-heme. Heme iron attaches to animal proteins and is better absorbed than non-heme iron. Meat, seafood, and poultry contain heme and non-heme iron. Plant-based foods have only non-heme iron.
Despite their diet differences, vegetarians and non-vegetarians are at risk for iron deficiency. Research published in Health found 66% of the vegetarians and 65% of non-vegetarians studied failed to meet the iron RDA.
Men 19-50 require 8 mg of iron daily; women 18 mg. All adults over 51 require 8 mg daily. A vegetarian diet may result in symptoms of iron deficiency, also as anemia.
The Vegetarian Resource Group (VRG) recommends vegetarians eat plenty of dark green leafy vegetables and dried beans to help prevent iron deficiency. They add that eating foods high in vitamin C with foods containing iron increases iron absorption.
Vegetarians may be at risk for calcium deficiency. According to the VRG, calcium is necessary for a strong skeletal system and supports muscle and nerve activity. The RDA for calcium is 1,000 mg daily for adults 19-50 and men 51-70. Women over 50 and men over 71 require 1,200 mg daily.
Dairy products such as cow's milk, cheese, and yogurt are go-to calcium products, but there are good non-dairy sources of the mineral:
- Calcium-fortified soy milk
- Blackstrap molasses
- Calcium-fortified juice
- Calcium-set tofu
- Soybeans and soy nuts
- Bok choy
- Chinese cabbage
- Mustard greens
Iodine is necessary for thyroid health and a well-oiled metabolism. Iodine deficiency may cause a sluggish metabolism, lowered immunity, anxiety, breast issues, reduced organ function, and thyroid problems, advises the Global Healing Center.
The iodine RDA for women and men over 19 years is 150 mcg daily. According to The Vegan Society, it's difficult to determine how much iodine is in food. Iodized salt seems like an obvious solution, but it's easy to exceed the daily limit. Instead, talk to your doctor about taking an iodine supplement.
Proteins are the building blocks of the body. You can't experience good health without them, or you may begin to experience protein deficiency symptoms.
Women 18 years and over generally require 46 grams of protein daily. Men 18 years require 52 grams; men 19 and over require 56 grams. It's believed vegetarians are more at risk to develop protein deficiency than non-vegetarians, but that's not necessarily true. Although meat, dairy products, and eggs are high in protein, so are many plant-based foods such as:
- Meat substitute products
- Nuts and seeds
- Nut butters
- Spinach (raw)
- Non-dairy milk
It used to be widely-accepted that plant-based proteins are incomplete and should be combined to create complete proteins; however, some nutritionists and doctors including Jeff Novak, MS, RD, say that is a myth. Current Centers for Disease Control guidelines fall somewhere in the middle. They recognize it's unnecessary to eat complementary proteins at the same meal but still recommend they be eaten throughout the same day.
How to Know if You're Nutrient-Deficient
Nutrient deficiencies are elusive. Symptoms may be vague and resemble other conditions or become severe before you take notice. If you develop persistent, unexplained symptoms such as fatigue, weakness, lightheadedness, cognitive or mood issues, or pain, consult your doctor. Tests can be ordered to measure vitamin and mineral levels.
In some cases, supplementation may be needed; however, your shouldn't self-diagnose or try to cure a suspected vitamin deficiency. Work with your doctor to determine what's going on and map out a treatment plan.