Dietary silicon intake and absorption.
BACKGROUND
Increasing evidence suggests that silicon is important in bone formation. The main source of silicon for humans is the diet, but the bioavailability of silicon from solid foods is not well understood.


OBJECTIVE
We estimated the dietary intake of silicon by adults, separately for men and women and for different age groups. Foods that were major contributors to silicon intake were identified. We then estimated the gastrointestinal uptake of silicon from major food sources and studied how uptake correlated with the silicon contents of the foods.


METHODS
Silicon intakes were determined in cohorts from the original Framingham Study and the Framingham Offspring Study by using a 126-item food-frequency questionnaire. Gastrointestinal uptake of silicon from foods was estimated in 3-8 healthy subjects by using urinary silicon excretion as a surrogate measure of silicon uptake.


RESULTS
Mean silicon intakes in men (30 and 33 mg/d in the original Framingham and Framingham Offspring cohorts, respectively) were significantly higher than those in women (24 and 25 mg/d in the 2 cohorts, respectively; P = 0.0001). Silicon intake decreased with age (P < 0.001, adjusted for sex). The major food sources were beer and bananas in men and bananas and string beans in women. Silicon was readily available from foods; a mean of 41% of the ingested silicon was excreted in urine. The silicon content of the foods consumed was significantly correlated with urinary silicon excretion (P = 0.019).


CONCLUSIONS
Solid foods are a major source of available silicon. The association between dietary silicon intake and bone health should now be investigated.
Jugdaohsingh
Ravin
R
Gastrointestinal Laboratory, The Rayne Institute, St Thomas' Hospital, London, UK. ravin.jugdaohsingh@kcl.ac.uk
Anderson
Simon H C
SH
Tucker
Katherine L
KL
Elliott
Hazel
H
Kiel
Douglas P
DP
Thompson
Richard P H
RP
Powell
Jonathan J
JJ
D000042:Absorption; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001682:Biological Availability; D015331:Cohort Studies; D004032:Diet; D004064:Digestive System / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012727:Sex Characteristics; D012825:Silicon / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D011795:Surveys and Questionnaires
D012825:Silicon