Critique 111: Association of alcohol consumption with a measure of osteoporosis in elderly women — 7 May 2013
Sommer I, Erkkilä AT, Järvinen R, Mursu J, Sirola J, Jurvelin JS, Kröger H, Tuppurainen M. Alcohol consumption and bone mineral density in elderly women. Public Health Nutr 2013;16:704-712. doi: 10.1017/S136898001200331X.
Objective: Findings regarding alcohol consumption and bone mineral density (BMD) in elderly women have been inconsistent. The objective of the present study was to explore the association of alcohol intake with BMD in elderly women.
Design: This cohort study included women from the population-based Kuopio Osteoporosis Risk Factor and Prevention – Fracture Prevention Study (OSTPRE-FPS). Alcohol intake and potential confounders were assessed at baseline and after 3 years of follow-up using a lifestyle questionnaire. In addition, an FFQ was distributed in the third year to measure dietary intake, including alcohol. Women underwent BMD measurements at the femoral neck and lumbar spine at baseline and after 3 years of follow-up.
Setting: Kuopio Province, Finland.
Subjects: Three hundred elderly women (mean age 67.8 years) who provided both BMD measurements and FFQ data.
Results: Alcohol consumption estimated from the FFQ and lifestyle questionnaire was significantly associated with BMD at both measurement sites after adjustment for potential confounders, including lifestyle and dietary factors (P <0.05). Using the FFQ, women drinking > 3 alcoholic drinks/week had significantly higher BMD than abstainers, 12.0% at the femoral neck and 9.2% at the lumbar spine. Results based on the lifestyle questionnaire showed higher BMD values for all alcohol-consuming women at the femoral neck and for women drinking 1–3 alcoholic beverages/week at the lumbar spine, compared with non-users.
Conclusions: The results from OSTPRE-FPS suggest that low to moderate alcohol intake may exert protective effects on bone health in elderly women.
The density of bones, measured as bone mineral density (BMD), is strongly related to osteoporosis. Elderly women with osteoporosis, in particular, are at increased risk of fractures of the hip, arm, and spine; such fractures often relate to severe disability. In many previous studies, but not all, women who report the moderate consumption of alcohol are at lower risk of osteoporosis and fractures. This study was based on alcohol data that had been collected in a study of the use of vitamin D and calcium supplementation in the prevention of osteoporosis.
Data were obtained from a subset of an original cohort of approximately 600 women who took part in a 3-year clinical trial to determine if the administration of vitamin D and Ca supplementation affected their BMD (there was apparently no effect of the intervention). Alcohol intake at baseline and follow up was estimated from questions included on a lifestyle questionnaire. At the end of the trial, a total of 341 women had provided both baseline and 3-year BMD measurements and, at follow up, had completed a food frequency questionnaire (FFQ) that provided a further estimate of alcohol consumption.
After those excluded due to incomplete data, data on 300 women were available for analysis. Of the women in the present analysis, one half had received additional vitamin D and calcium in the clinical trial and one half received no treatment. Even though no interaction between the Vitamin D/Calcium intervention and alcohol was seen, the group in the clinical trial to which each woman was assigned was included as a covariate in the analyses. It is noteworthy that most of the women in this study were abstainers or very light drinkers.
Alcohol assessments from the lifestyle questionnaire were very similar at baseline and follow up, so the mean alcohol value from the two measurements was used in the analysis. A separate analysis was done relating alcohol assessed by the FFQ to changes in BMD between baseline and follow up measurements. While the absolute amounts of alcohol estimated from the lifestyle questionnaire and the FFQ differed somewhat, there was a similar relation with BMD for both.
Specific comments on the study by Forum reviewers: Reviewer Ellison pointed out a number of limitations of the present study: “A rather small cohort with a very low intake of alcohol, a short duration of follow up, and rather small differences according to whether the women consumed alcohol or not. Still, the results show that consumers of alcohol had a greater increase in BMD than did abstainers, supporting much previous research.” Forum reviewer Finkel considered this topic to be “of considerable public-health importance, as it adds value to the alcohol-health constellation.”
Although the investigators adjusted for most relevant factors in their analyses, several members were concerned that residual confounding is still a possibility. The authors themselves state that “elderly women who drink alcohol seem to have a certain lifestyle pattern. They are more likely to smoke and exercise, have lower BMI, and are more likely to use hormone replacement therapy than alcohol-abstaining elderly women.” Reviewer De Gaetano agreed with this concern, and thought that, because of limitations, he was not sure that this study adds much to our knowledge on this subject.
On the other hand, Reviewer Skovenborg stated: “The study is well-done with a thorough control for established confounders in a population with a low intake of alcohol. The results confirm the findings from many earlier studies of a significant association between a moderate consumption of alcohol and a higher BMD with the best effect at no more than one drink per day.” Reviewer Svilaas also thought that this was a good study, but was surprised that “the women who consumed alcohol were more likely to smoke and were leaner, yet they had a higher BMD. Perhaps, they were more active?”
Is it alcohol or wine? Forum member Lanzmann-Petithory pointed out that “Osteoporosis is an important concern in Finland, as prevalence of osteoporosis there is about twice as high as it is in southern Europe. Finland was the country with the highest incidence of cardiovascular disease in the Seven Countries Study, and began an extensive public campaign (the North Karelia Project) in the early 1970s to lower cardiovascular risk. Further, Finland has been turning more and more towards wine in recent decades. For example, between 1961 and 2001, the consumption of pure alcohol increased from 2 liters to 7.4 liters /capita / year, while wine drinking increased from 1.3 to 20.1 liters / capita / year.
“I suspect that the moderate quantity of alcohol in this study, which was consumed by women who were 35 years old at the beginning of the North Karelia Project, could be mainly wine. Unfortunately, the size of the study is too small to evaluate potential differences by type of alcoholic beverage consumed, but the beneficial effect could relate to an increase in wine consumption in Finland in recent years.”
Factors associated with osteoporosis: Van Velden added his views on a number of factors related to osteoporosis: “It is well-known that pharmacological interventions to reduce bone turnover are costly and there is a significant potential for adverse effects, making population-wide drug therapy unsuitable for the primary prevention of osteoporosis. Modifiable lifestyle factors such as adequate calcium intake, vitamin D, exercise, and moderate alcohol intake have been identified to influence the risk of osteoporosis, and this well-done study merely confirms previous observations on the value of moderate alcohol consumption to reduce bone turnover markers. Although chronic alcohol abuse is associated with reductions in bone mineral density, moderate alcohol intake is associated with increased BMD.”
Van Velden continued: “The modern acidogenic Western-type diet is also associated with increased calcium loss from bone, and alkalinization of the diet increases osteoblastic (bone formation markers) and decreases osteoclastic (bone resorption) markers. Osteoporosis is more prevalent in people with a high acidogenic diet, mostly because of the consumption of a diet high in animal protein. The Mediterranean diet, high in vegetables and fruit, is a more alkaline diet, and this may also play a role in the prevention of osteoporosis. It would be interesting to know whether wine is acidogenic or alkaline when consumed; the ascorbic acid in wine is rapidly converted to alkaline products. However, it is important to remember that alcohol can never be seen in isolation from other aspects of diet and lifestyle.”
The density of bones, measured as bone mineral density (BMD), is strongly related to osteoporosis. Elderly women with osteoporosis, in particular, are at increased risk of fractures of the hip, arm, and spine; such fractures often relate to severe disability. With data on alcohol collected as part of a clinical trial on the prevention of osteoporosis, investigators in Finland have related alcohol consumption to changes over three years in BMD. After those excluded due to incomplete data, data on 300 women were available for analysis. The majority of women were abstainers or consumed little alcohol. Nevertheless, the results support much earlier research: regular, moderate drinking is associated with higher levels of BMD (i.e., lower risk of osteoporotic fractures) than is abstinence.
Forum reviewers, as did the authors, noted a number of limitations of the study: a rather small cohort with a very low intake of alcohol, a short duration of follow up, and rather small differences according to whether the women consumed alcohol or not.
Data from European surveys have shown that women in Finland tend to have high levels of osteoporosis and to drink very little; hence the increase in BMD associated with alcohol intake, even though slight, could be important in this population. Over the past three decades, there has been an increase in alcohol consumption in Finland, especially a marked increase in the consumption of wine. Hence, some Forum reviewers thought that the improvement in BMD among drinkers in this study may have been primarily from wine (which may have additional components, other than alcohol, that relate to BMD). However, the number of subjects was not large enough to test this hypothesis in the present study. Overall, this study supports the premise that moderate alcohol intake, along with an adequate calcium intake and vitamin D and exercise, may have a favorable influence on the risk of developing osteoporosis
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Comments on this critique by the International Scientific Forum on Alcohol Research were provided by the following members:
Giovanni de Gaetano, MD, PhD, Research Laboratories, Catholic University, Campobasso, Italy
Arne Svilaas, MD, PhD, general practice and lipidology, Oslo University Hospital, Oslo, Norway
Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA
Dominique Lanzmann-Petithory,MD, PhD, Nutrition/Cardiology, Praticien Hospitalier Hôpital Emile Roux, Paris, France
Erik Skovenborg, MD, Scandinavian Medical Alcohol Board, Practitioner, Aarhus, Denmark
Yuqing Zhang, MD, DSc, Epidemiology, Boston University School of Medicine, Boston, MA, USA
David Van Velden, MD, Dept. of Pathology, Stellenbosch University, Stellenbosch, South Africa
Dag S. Thelle, MD, PhD, Senior Professor of Cardiovascular Epidemiology and Prevention, University of Gothenburg, Sweden; Senior Professor of Quantitative Medicine at the University of Oslo, Norway
R. Curtis Ellison, MD, Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Boston, MA, USA