Osteoporosis and Yogurt

A recent study from Trinity College in Dublin, Ireland is the largest observational study to date of bone measurements in older men and women and dairy intake.  After taking into account traditional risk factors for bone strength or frailty, the researchers found that increased yogurt intake was associated with higher hip bone density and a significantly reduced risk of osteoporosis in older Irish men and women. 

The study analyzed a wide ranged of factors that could contribute to bone strength or weakness, such as BMI, kidney function, physical activity or inactivity, servings of milk or cheese, calcium and vitamin D supplements, smoking, and alcohol use. After adjusting for these factors, total hip and femoral neck bone density in women were 3.1 – 3.9% higher among those with the highest yogurt intakes compared to the lowest.  In men, the biomarker of bone breakdown was 9.5% lower in those with the highest yogurt intakes compared to the lowest – showing reduced bone turnover.  Vitamin D supplements were also associated with significantly reduced risk in both men and women.

Lead author of the study and research fellow at the Centre for Medical Gerontology, Trinity, Dr Eamon Laird said: "Yogurt is a rich source of different bone promoting nutrients and thus our findings in some ways are not surprising. The data suggest that improving yogurt intakes could be a strategy for maintaining bone health but it needs verification through future research as it is observational."

Dr Miriam Casey, senior investigator of this study and Consultant Physician at St James's Hospital Dublin said: "The results demonstrate a significant association of bone health and frailty with a relatively simple and cheap food product. What is now needed is verification of these observations from randomized controlled trials as we still don't understand the exact mechanisms which could be due to the benefits of micro-biota or the macro and micro nutrient composition of the yogurt."

The study included 1,057 women and 763 men who underwent a bone-mineral-density (BMD) assessment and 2,624 women and 1,290 men who had their physical function measured. Yogurt consumption information was obtained from a questionnaire and categorized as never, 2-3 times per week and more than one serving per day.

The Irish study did not look at the type of yogurt eaten, and whether it was sweetened or unsweetened.  However, it is wise to consider the fat and sugar content of the yogurt you eat if you are planning to increase your intake.  A study done by Kaiser Permanente researchers suggests that women with breast cancer should avoid high-fat dairy foods, which may contain more estrogen from the cows’ milk fat.  Avoiding too much sugar in your diet, a smart move for all of us, may mean that you find ways to enjoy plain yogurt with fruit, or eat it as they do in India, with spicy lentils (dal).

Previous studies on milk intake and osteoporosis have shown mixed results in terms of fractures and bone density.  One study showed benefits from both milk and yogurt in the diet.  This is the first large study to show that yogurt may be more beneficial than other dairy products.

Sadja Greenwood,  MD, MPH