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Diet Alert: Vegetarianism and the Risks of Anorexia Nervosa

By James Greenblatt, MD

Your family sits down to dinner one evening and your fourteen-year-old daughter looks with disgust at the plate of chicken placed in front of her. “I’m not eating that,” she declares, seemingly out of the blue. 

“I’ve decided to be a vegetarian.”

As a parent, you may be unsure how to respond. Is she serious or is it a phase and likely to be short-lived? What if it isn’t?

More practical questions soon pop into mind: when did she decide this? Why? What exactly does she plan to eat? How will her body get enough protein? Should I be worried about her?

The answer to that question is straightforward: probably.

The Many Types of Vegetarians

Vegetarianism is generally defined as the practice of not eating food products derived from animals—generally meat, poultry, or fish, or their by-products. There are many different types of vegetarianism, however, and some types do allow for the consumption of eggs and/or dairy products.

Some vegans and vegetarians manage to eat a variety of protein, fat, carbohydrates, vitamins, and minerals, but many do not—and it is this latter group that studies have found to be less healthy than their non-vegetarian peers. (ref. 1-3) 

The Connection to Anorexia

It has not yet been consistently demonstrated that being vegetarian can cause the development of symptoms of anorexia, although the results of some studies are a bit alarming. 

Seven different studies have assessed eating attitudes and behaviors among a total sample of 754 vegetarian students and 10,093 non-vegetarian students. Overall, the vegetarians in this study were significantly more likely to disclose dieting, weight preoccupation, body dissatisfaction, taking laxatives, intentionally vomiting, binge eating, and having an eating disorder. (ref. 4,5-11)

Multiple studies have demonstrated that women with anorexia report an aversion to foods with high protein content, such as red meat, fish, milk, and eggs. (ref. 12) One group of researchers documented the prevalence of vegetarianism among a sample of patients with anorexia to be approximately fifty percent while another research group found it to be forty-five percent. (ref. 13,14 )

Research also demonstrates that vegetarians with anorexia are more “weight-phobic” than their non-vegetarian counterparts. (ref. 13)

Nutritional Deficiencies in Teenage Vegetarians

Although troubling, the association between vegetarianism and anorexia is only part of the picture. The deficiencies of key nutrients that are likely to result from the typical teenage diet, minus meat and other high-protein foods, can set the stage for future mental health problems.

Protein

Studies have found that when teenagers decide to stop eating meat products, they often fail to consistently substitute other high-protein foods in order to continue to meet the body’s intrinsic requirements for proteins and amino acids (the building blocks of proteins). 

While teenage vegetarian diets may contain sufficient calories thanks to high-sugar, high-calorie foods, these diets typically do not fulfill the nutritional requirements of a growing body. 

Some of the most common deficiencies observed in teenage vegetarians are zinc, vitamin B12, essential fats, and tryptophan, all of which are found in high-protein foods and may play critical roles in the development and progression of anorexia.

Zinc

Female vegetarians have been found to have measurably lower levels of zinc in their blood, urine, and hair compared to non-vegetarians. (ref. 15) This makes sense when you consider that the most commonly consumed sources of dietary zinc in the United States are beef and poultry.

To make matters worse, the small amount of zinc that vegetarians do consume is not absorbed well. Many of the plant foods highest in zinc, such as beans, whole grains, nuts, and seeds, are also high in substances called phytates, which block zinc absorption. It is estimated that vegetarians need to consume fifty percent more zinc per day than non-vegetarians in order to achieve the recommended dietary amount. (ref. 16-18) 

Too little zinc in the diet can contribute to anorexia by promoting a decrease in appetite and sense of taste, an aversion to meat, depression, anxiety, and digestive problems with meals.

Vitamin B12

Vitamin B12 is an essential nutrient found primarily in meat, eggs, and dairy products. Because vegans do not eat these foods, they are often at risk of developing a B12 deficiency. And although some plants do contain a slightly different form of vitamin B12, they do not appear to be reliable or effective sources of the vitamin.

Among other things, a vitamin B12 deficiency can lead to decreased production of neurotransmitters, including serotonin, norepinephrine, and dopamine. Low vitamin B12 levels can cause potentially severe mental health symptoms, including depression and anxiety. (ref. 19)

In my practice, anxiety and panic attacks are often the most dramatic symptoms associated with low B12 levels. When B12 levels return to normal, anxiety consistently decreases.

Tryptophan

Amino acids are necessary for building new cells, making hormones, and repairing the body. Linked together in different combinations, they are also the building blocks of proteins. Amino acids are needed to make everything in the body—from brain cells to skin, from muscles to bone and are precursors to most neurotransmitters in the brain. They are required, for example, for the production of serotonin, dopamine, and norepinephrine.

Low dietary intake of tryptophan can cause inadequate serotonin synthesis in the brain, a phenomenon that has been associated with depressed mood as it is a precursor for serotonin. (ref. 20,21) The body cannot synthesize it and, accordingly, it must be obtained from food. In fact, many psychiatrists believe that the poor response to antidepressant medications in patients with anorexia is due to low serotonin levels. (ref. 22,23)

Deficiencies in zinc, B12, and/or tryptophan can exacerbate the underlying symptoms of anorexia, contributing to the onset and continuation of the disease and hindering recovery.

If Your Child Decides to Become a Vegetarian

Discussing the importance of nutrients, and then devising and following a well-balanced vegetarian diet, can help prevent your child from developing nutritional deficiencies and can facilitate his or her ongoing physical and mental health. Consider seeking a registered dietitian who specializes in working with eating disorder patients; such a professional can also assist with dietary planning.

There are obvious concerns that arise when a child decides to become vegetarian, especially if he or she has previously eaten meat products. 

If your child unexpectedly decides to become a vegetarian, it is important to try to determine whether the decision stems from an ideological choice or is being used as an excuse to restrict food.

Here are some questions you can ask your child that may help identify the reason(s) underlying his or her decision to become vegetarian:

  • Can you tell me why you’ve decided to be vegetarian?
  • Does meat taste strange or different to you?
  • Does your stomach hurt when you eat meat?
  • Does eating meat make you feel nauseated?
  • Have you been reading or learning about cruelty to animals? If so, is that important to you?
  • Are you comfortable with the way your body looks?
  • Are you trying to lose weight?

If your child suddenly stops eating meat, concerns about nutritional deficiencies that may arise as a result become very real and highly valid. By preparing your child’s meals, you can better ensure that he or she will continue to eat a well-balanced diet of protein, fruits, vegetables, and whole grains. If, however, your child is like many other teenage vegetarians and subsists primarily on white flour- and sugar-based products, you will want to begin discussing the following topics with him or her:

  • The importance of getting enough vitamins, minerals, essential fatty acids, and antioxidants in the diet, and what diseases or symptoms can develop when the diet is deficient in these nutrients.
  • How zinc deficiency can cause decreased appetite, weight loss, depression, and altered taste perception—all of which may lead to the development of anorexia.
  • How eating adequate amounts of protein is important for normal physical and psychological development.
  • The need to take certain nutritional supplements to avoid deficiencies and stay healthy.

What Should You Do if Your Child Says They Will No Longer Eat Meat?

Firstly, treat the decision to avoid a specific food group as a red flag. Both you and your teen’s healthcare provider must take this change of events seriously.

Remember:

  • Becoming vegetarian may be an excuse to begin restricting food intake.
  • Vegetarianism is very common in anorexia.
  • Teenage vegetarian diets, in general, can be highly nutrient-deficient.
  • Inadequate protein intake can lead to deficiencies of zinc, vitamin B12, and tryptophan—three nutrients that play vital roles in mood and mental health.

It is possible that your child may be just fine on a vegetarian diet. But it is also possible—and equally as likely—that he or she may have a greater biological requirement for nutrients such as zinc, B12, or tryptophan, all of which are concentrated in meat sources. 

Of course, if your teen’s decision to become a vegetarian is accompanied by any overt behavioral changes that concern you—such as drastically reducing his or her food intake, eating alone, or engaging in ritualistic behaviors around food—it is imperative that you consult with a mental health professional.

References:

  1. Burkert NT, Muckenhuber J, Großschädl F, Rásky E, Freidl W. Nutrition and health – the association between eating behavior and various health parameters: a matched sample study. PLoS One. 2014;9(2):e88278. 
  2. Michalak J, Zhang XC, Jacobi F. Vegetarian diet and mental disorders: results from a representative community survey. Int J Behav Nutr Phys Act. 2012;9:67.
  3. Herrmann W, Schorr H, Obeid R, Geisel J. Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians. Am J Clin Nutr. 2003;78(1):131-136.
  4. Perry CL, Mcguire MT, Neumark-Sztainer D, Story M. Characteristics of vegetarian adolescents in a multiethnic urban population. J Adolesc Health. 2001;29(6):406-416.
  5. Quick V, Byrd-Bredbenner C. Vegetarians and vegans: are they at increased risk for disordered eating and poor psychological well-being? J Acad Nutr Diet. 2013;113(9 Suppl 3):A–89. 
  6. Robinson-O’Brien R, Perry CL, Wall MM, Story M, Neumark-Sztainer D. Adolescent and young adult vegetarianism: better dietary intake and weight outcomes but increased risk of disordered eating behaviors. J Am Diet Assoc. 2009;109(4):648-655.
  7. Baş M, Karabudak E, Kiziltan G. Vegetarianism and eating disorders: association between eating attitudes and other psychological factors among Turkish adolescents. Appetite. 2005;44(3):309-315.
  8. Klopp SA, Heiss CJ, Smith HS. Self-reported vegetarianism may be a marker for college women at risk for disordered eating. J Am Diet Assoc. 2003;103(6):745-747.
  9. Perry CL, McGuire MT, Neumark-Sztainer D, Story M. Adolescent vegetarians: how well do their dietary patterns meet the healthy people 2010 objectives?. Arch Pediatr Adolesc Med. 2002;156(5):431-437.
  10. Lindeman M, Stark K, Latvala K. Vegetarianism and eating-disordered thinking. Eat Disord. 2000;8(2):157-165.
  11. Neumark-Sztainer D, Story M, Resnick MD, Blum RW. Adolescent vegetarians. A behavioral profile of a school-based population in Minnesota. Arch Pediatr Adolesc Med. 1997;151(8):833-838.
  12. Robinson-O’Brien R, Perry CL, Wall MM, Story M, Neumark-Sztainer D. Adolescent and young adult vegetarianism: better dietary intake and weight outcomes but increased risk of disordered eating behaviors. J Am Diet Assoc. 2009;109(4):648-655.
  13. Bardone-Cone AM, Fitzsimmons-Craft EE, Harney MB et al. The inter-relationships between vegetarianism and eating disorders among females. J Acad Nutr Diet. 2012;112(8):1247-1252.
  14. Kadambari R, Cowers S, Crisp A. Some correlates of vegetarianism in anorexia nervosa. Int J Eat Disord. 1986;5(3):539-544.
  15. Foster M, Chu A, Petocz P, Samman S. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. J Sci Food Agric. 2013;93(10):2362-2371
  16. Saunders AV, Craig WJ, Baines SK. Zinc and vegetarian diets. Med J Aust. 2013;199(S4):S17-S21. 
  17. Chiplonkar SA, Agte VV. Predicting bioavailable zinc from lower phytate forms, folic acid and their interactions with zinc in vegetarian meals. J Am Coll Nutr. 2006;25(1):26-33.
  18. Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Washington, D.C.: National Academy Press; 2001.
  19. Rzepka Z, Rok J, Kowalska J, et al. Astrogliosis in an experimental model of hypovitaminosis B12: a cellular basis of neurological disorders due to cobalamin deficiency. Cells. 2020;9(10):2261. 
  20. Kötting WF, Bubenzer S, Helmbold K, Eisert A, Gaber TJ, Zepf FD. Effects of tryptophan depletion on reactive aggression and aggressive decision-making in young people with ADHD. Acta Psychiatr Scand. 2013;128(2):114-123.
  21. Evers EA, Sambeth A, Ramaekers JG, Riedel WJ, van der Veen FM. The effects of acute tryptophan depletion on brain activation during cognition and emotional processing in healthy volunteers. Curr Pharm Des. 2010;16(18):1998-2011.
  22. Kaye WH, Fudge JL, Paulus M. New insights into symptoms and neurocircuit function of anorexia nervosa. Nat Rev Neurosci. 2009;10(8):573-584.
  23. Kaye WH, Barbarich NC, Putnam K, et al. Anxiolytic effects of acute tryptophan depletion in anorexia nervosa. Int J Eat Disord. 2003;33(3):257-270.

 

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2 Comments

  1. Sarah Rowland EDCS (NZ)

    This is an incredible resource – thank you so much Dr James Greenblatt.
    What is really shocking is when Inpatient facilities allow such a diet to be initiated when it wasn’t previously a family diet.
    We have to be really honest with ourselves, potentially challenging our own beliefs and ask the hard question – do we really want to jeopardise our loved one’s recovery or life over their malnourished minds demands?

  2. Kay Wilson

    My daughter was vegetarian for years before she was diagnosed with anorexia. We were successful in refeeding her and getting her to recovery with a primarily plant-based diet. We tried at first to go the route suggested of adding high fats animal-based and it did a number on her system. When we switched to plant-based high fats like avocadoes, coconut, nut butters, nuts, seeds and coconut/avocado oils, she was much better off. Now recovered, our daughter has moved to a vegan lifestyle and we as parents joined her. It has opened up so much to her variety of foods and love for eating and cooking. And her self-awareness and body image is very good too. Lots of benefits to vegetarianism and veganism and it can be done successfully with eating disorders. Acceptance and knowledge of how to care for patients with these diets is necessary as our culture slowly moves away from meet for health, environmental and animal rights reasons.

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