Wheat bran supplementation does not affect biochemical markers of bone turnover in young adult women with recommended calcium intake

Abstract

We investigated the effect of wheat bran on biochemical indicators of Ca and bone metabolism in nineteen healthy women, aged 25·5 (se 0·9) years. Subjects received six wheat bran biscuits or six white flour biscuits per day for a period of 4 weeks (crossover). Wheat bran consumption increased fibre intake from 17·7 (se 1·3) to 29·6 (se 1·3) g/d (7 d food record) and enhanced P intake from 1225 (se 59) mg/d to 1663 (se 65) mg/d; P < 0·001. Mean daily Ca intake during wheat bran consumption (1110 (se 82) mg/d) significantly (P = 0·008) exceeded Ca ingestion during the white flour period (955 (se 67) mg/d). Wheat bran increased the number of defecations per week from 7·9 (se 0·8) to 12·2 (se 1·4) (P = 0·0018). Urinary Ca excretion over 24 h significantly (P = 0·021) decreased from 473 (se 53) μmol/mmol creatinine (control period) to 339 (se 37) μmol/mmol creatinine (wheat bran period). Serum 25-hydroxyvitamin D, 2 h fasting urinary Ca/creatinine excretions and 24 h urinary P excretion remained constant. No differences in serum levels of carboxy-terminal propeptide of type I procollagen (biomarker of bone formation) or in 2 h fasting urinary hydroxyproline/creatinine excretions (biomarker of bone resorption) were observed at the end of the two cycles of dietary supplementation. We conclude that a high fibre intake of approximately 30 g/d has no significant adverse effects on bone turnover in subjects with Ca intakes above 1000 mg/d and that the reduction in 24 h urinary Ca excretion is most probably the result of an adaptation process, induced by a decrease in net absorbed Ca.

Wheat bran: its composition and benefits to health, a European perspective

“…Whether this is of physiological significance in terms of bone health has been explored further. Short-term (4 weeks) and longer-term (2 years) studies have demonstrated that wheat bran in the diet had no significant effect on bone turnover markers in young and older women (Zitterman et al 1999; Chen et al 2004). Therefore, despite the negative effects of wheat bran on calcium bioavailability, there is insufficient evidence to suggest that it has any detrimental effect on bone metabolism, causing accelerated bone loss.…”

Whole grain intake, incident hip fracture and presumed frailty in the Iowa Women's Health Study

“…In a study of 19 healthy young women (mean age: 25.7 ± 3.9 years), Zittermann et al found no difference in serum biomarkers of bone turnover between the high wheat bran fiber (15g/d) and low wheat bran fiber (1g/d) supplementation groups (16) . Similarly, in a study of healthy individuals in southern India, Harinarayan et al found no difference in PTH levels between 205 participants living in rural areas consuming high phytate/calcium diets and 943 participants living in urban areas consuming low phytate/calcium diets, although both groups had low dietary calcium intake and were vitamin D deficient (13) .…”

“…Accordingly, the 2005 US Dietary Guidelines recommend that at least half of the recommended 6–11 grain servings/d comprise whole grain foods ( 8 ) . However, one potential concern is whether the phytic acid in the whole grain foods leads to an increased risk of hip fracture by reducing the bioavailability of dietary minerals ( 9 – 16 ) , in particular, that of co-ingested Ca. Thus, increased whole grain consumption could have an adverse effect on bone metabolism ( 13 ) , potentially increasing the risk of fracture ( 14 ) .…”

“…Most studies concerned with this phenomenon have been either in vitro ( 11 ) or short-term human feeding studies which measured Ca binding or biomarkers of bone turnover ( 15 , 16 ) . Findings from balance studies ( 10 , 16 ) have been inconsistent, possibly due to imprecise measurements of Ca absorption.…”

Supportive Ernährungsmaßnahmen für Prävention und Therapie der Osteoporose

“…Ursächlich ist der Gehalt an Phytinsäure zu betrachten [18]. Jedoch wird bei knochengesunden jungen Frauen der absorptionshemmende Effekt von enteral zugeführten 14 g Weizenkleie durch einen sofortigen Abfall der renalen Kalziumexkretion kompensiert [20]. Die intestinale Absorption von Kalzium kann durch Vitamin D deutlich verbessert werden.…”