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- Yerba Maté (Ilex paraguariensis)
- Postmenopause
- Bone Mineral Density
| Date:
01-13-2012 | HC# 121161-440
|
Re: Yerba Maté Consumption over Time Preserves Bone Mineral Density in Postmenopausal Women
Conforti A, Gallo ME, Saraví FD. Yerba maté (Ilex paraguariensis) consumption is
associated with higher bone mineral density in postmenopausal women. Bone. September 3, 2011; [epub ahead of
print]. doi:10.1016/j.bone.2011.08.029.
Osteoporosis,
characterized in part by low bone mineral density (BMD) and frequent fractures,
affects women worldwide. An infusion of yerba maté (Ilex paraguariensis) leaves and stems is commonly consumed in Latin America. Yerba maté contains caffeine, a compound
thought to contribute to low BMD, higher bone loss, and increased fracture
risk; however, both green and black teas (Camellia
sinensis) have been found to positively impact BMD, perhaps due to other
compounds present. As lifestyle factors such as diet may influence osteoporosis
and BMD in particular, this observational, cross-sectional study investigated
the impact of yerba maté consumption on BMD. In particular, it was hypothesized
that yerba maté consumption would negatively impact BMD due to caffeine content,
and the BMD of the lumbar spine and the femoral neck of yerba maté consumers
were compared to those of non-consumers.
Women
included consumed 1 L of yerba maté daily for 5 years as a traditional
preparation and were compared with non-drinkers matched in age and years
postmenopause. Women were excluded if they had early menopause (<45 years
old), were current or past smokers, consumed more than 3 cups of coffee or tea
daily, drank more than 50 g of alcohol a week, or were on hormone replacement
therapy (HRT). Also, women that had biphosphonate treatment longer than 6
months, who were being treated with corticosteroids, or had any health issue
that affected calcium metabolism were excluded. Power was calculated at n=142
to detect a 5% difference in femoral neck BMD with a power of 0.80 and an alpha
of 0.05. A nutrition survey was utilized to assess calcium intake, and urine
was measured to detect excretion of calcium and phosphate. In addition, body
mass index (BMI) was calculated for all patients, and BMD was measured by dual energy
X-ray absorptiometry.
A total of 146 women
were enrolled in the study. There were no significant differences in age, time
since menopause, height, BMI, and calcium intake or excretion, phosphate
excretion, or frequency of low-impact bone fractures between yerba maté
drinkers and non-drinkers; however, yerba maté drinkers had a significantly higher
BMI by 1.1 kg/m2 than non-drinkers (P=0.0294). When BMD was assessed
between groups, it was found that yerba maté drinkers had significantly higher (9.7%)
median lumbar spine BMD (0.952 g/cm2 vs. 0.858 g/cm2,
P<0.0001). Similarly, the median femoral neck BMD of the yerba maté drinkers
was significantly greater (6.2%) than the non-drinkers (0.817 g/cm2
vs. 0.776 g/cm2, P=0.0002).
Linear
regression analysis was used to compare lumbar spine BMD to femoral neck BMD
for both groups. The relationship was significant for both groups (P<0.0001)
but not significantly different between groups. Linear regression analysis of
age vs. both lumbar spine and femoral neck BMD revealed no significant
differences between the slopes of the groups. A multiple regression model
revealed a significant negative association with years of menopause vs. lumbar
spine BMD (P<0.0001) and significant positive associations vs. BMI
(P<0.0496) and yerba maté drinking (P<0.0001). When analyzing femoral
neck BMD vs. age, a significant negative association was observed (P<0.0001),
but positive associations were reported with BMI (P<0.0001) and yerba maté
consumption (P<0.0028). The r2 for lumbar spine BMD was 0.1573
(P<0.0001) and 0.1592 (P<0.0001) for femoral neck BMD.
On
the basis of the reported results indicating that yerba maté had a positive
effect on BMD, the original hypothesis of yerba maté decreasing BMD was
rejected. Yerba maté is widely consumed in Argentina, Brazil, Paraguay, and
Uruguay and mostly found to have beneficial health effects such as antioxidant
and anticancer properties. Despite this, consuming very hot yerba maté has been
found to be correlated with certain oral cancers.
This
study reports a 9.7% and 6.2% higher lumbar spine and femoral neck BMD in yerba
maté drinkers than non-drinkers, respectively, as compared with 4.3% and 4.7%
higher BMD in the lumbar spine and femoral neck BMD of Chinese tea drinkers.
This suggests that yerba maté may potentially be a more effective dietary
factor for improving BMD than tea. It is discussed that this study may not
reflect osteoporosis in the wider population and only reports results for a
specific demographic. Although the calcium content of yerba maté leaves, as
well as the content of both calcium and fluoride in the local water is argued
to be negligible, other bioactive compounds reported to be present in yerba maté
may have played a role in the bioactivity reported here.
—Amy C. Keller,
PhD
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