Increased risk of iodine deficiency with vegetarian nutrition.
Observational studies primarily based on diet questionnaires or food records have reported that vegetarians can have a very low I intake. However, analytically ascertained data on the possible degree of I deficiency with this form of diet is lacking. Six healthy adult volunteers participated in the present controlled experimental diet study carried out in four separate 5 d diet periods. The study diets, normal, protein-rich, lactovegetarian, and repeat of the initial normal diet, were almost isoenergetic and contained no fish, sea food, iodized salt or processed foods fortified with I. During the last 48 h of each diet period two 24 h urine samples were obtained from each subject. I analyses were performed in the urine samples and in representative samples taken from all ingested diets. Urinary I excretion was significantly lower with the lactovegetarian diet (36.6 (SD 8.8) micrograms/d) than with the normal and the protein-rich diets (50.2 (SD 14.0) and 61.0 (SD 8.0) micrograms/d respectively). Accordingly, a markedly reduced I intake was confirmed analytically for the lactovegetarian diet (15.6 micrograms/d v. 35.2 and 44.5 micrograms/d respectively). Our results provide experimental confirmation of literature findings indicating that I supply is higher with non-vegetarian than with vegetarian diets. Specifically, the extremely low intake and urinary output of I as analytically determined for one exemplary vegetarian diet, demonstrate that dietary I may be limiting when strict forms of vegetarian dietary practices (no iodized salt, no I supplements) are followed. The present study is, therefore, the first diet-experiment-based pointer to the potential danger of I deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low I levels are ingested.
Remer
T
T
Research Institute of Child Nutrition, Dortmund, Germany. remer@fke.uni-dortmund.de
Neubert
A
A
Manz
F
F
D000328:Adult; D000704:Analysis of Variance; D003677:Deficiency Diseases / Q000209:etiology; D014676:Diet, Vegetarian / Q000009:adverse effects*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013961:Thyroid Gland / Q000378:metabolism
D004044:Dietary Proteins; D007455:Iodine