Definitive New Research Review Sets the Record Straight About Dairy
Sat. April 1, 2000 12:00 AM by Business Wire
Rosemont, IL -
A comprehensive body of research published today in the Journal of the American College of Nutrition by prominent calcium researcher Robert P. Heaney, MD, of Creighton University in Omaha suggests that a diet devoid of dairy products could lead to bone fractures.
Dairy products provide a unique mix of minerals -- calcium, phosphorus and potassium -- that all contribute to maximizing bone density and slowing age-related bone loss. Calcium intake may be the most critical, considering that calcium is a major component of bones.
In this new report, Heaney reviews 138 studies exploring the relationship between bone health and calcium intake, including numerous studies that used dairy products as the calcium source. He also examines the quality of the published studies and sorts them according to two main categories: randomized controlled trials -- the "gold standard" of clinical research studies -- and observational studies, or research that suggests relationships based on observing population groups (see sidebar).
"The scientific evidence is overwhelming that lifelong calcium intake is one of the most significant factors determining your risk of an osteoporotic fracture," Heaney said. "Well-designed clinical interventions have demonstrated time and time again that increasing calcium intake halts bone loss or even builds bone in older women, and decreases the risk of fracture."
Lately, Heaney added, there has been a lot of confusion among consumers and some medical professionals because a few observational studies did not show a connection. "The limitations of this observational research must be addressed," he said. "You can't establish or disprove a cause and effect relationship with this type of study."
For example, one highly publicized Harvard study that examined the diets of nurses over 12 years did not show a connection between milk or other food sources of calcium and fracture incidence. In his comprehensive review, Heaney points out the limitations of this study and helps put it in perspective.
"For starters, this study is entirely inconclusive because the researchers did not control the subjects' calcium intake, but merely asked them about it," he said. "Any study using food questionnaires should be viewed with caution. This assessment tool is imperfect at best. Nevertheless, despite the many weaknesses of observational studies, fully three-fourths of all such studies have been positive -- an indication of just how strong the connection between calcium and bone health really is."
Even more importantly, Heaney cites nearly 50 recent randomized, controlled trials in his report that provide conclusive evidence that calcium helps prevent bone loss and fractures, a painful and debilitating problem for 1.5 million women each year. Many of these studies specifically used dairy products as the calcium source. (Calcium supplements are often used in research studies to help gain greater control, yet health professionals recommend food sources -- like dairy foods -- as the preferred source of calcium.).
Heaney said these reports far outweigh any observational studies that are speculative and do not show a causal relationship. "You need to look at the entire body of evidence -- not a single study that fails to find what well-designed clinical investigations have shown.
"Dairy foods play a valuable role in the diet, and it's extremely difficult to get the calcium you need without milk or milk products. Their role in building and maintaining strong bones is well documented," asserts Heaney.
Dairy products provide a unique mix of minerals -- calcium, phosphorus and potassium -- that all contribute to maximizing bone density and slowing age-related bone loss. Calcium intake may be the most critical, considering that calcium is a major component of bones.
In this new report, Heaney reviews 138 studies exploring the relationship between bone health and calcium intake, including numerous studies that used dairy products as the calcium source. He also examines the quality of the published studies and sorts them according to two main categories: randomized controlled trials -- the "gold standard" of clinical research studies -- and observational studies, or research that suggests relationships based on observing population groups (see sidebar).
"The scientific evidence is overwhelming that lifelong calcium intake is one of the most significant factors determining your risk of an osteoporotic fracture," Heaney said. "Well-designed clinical interventions have demonstrated time and time again that increasing calcium intake halts bone loss or even builds bone in older women, and decreases the risk of fracture."
Lately, Heaney added, there has been a lot of confusion among consumers and some medical professionals because a few observational studies did not show a connection. "The limitations of this observational research must be addressed," he said. "You can't establish or disprove a cause and effect relationship with this type of study."
For example, one highly publicized Harvard study that examined the diets of nurses over 12 years did not show a connection between milk or other food sources of calcium and fracture incidence. In his comprehensive review, Heaney points out the limitations of this study and helps put it in perspective.
"For starters, this study is entirely inconclusive because the researchers did not control the subjects' calcium intake, but merely asked them about it," he said. "Any study using food questionnaires should be viewed with caution. This assessment tool is imperfect at best. Nevertheless, despite the many weaknesses of observational studies, fully three-fourths of all such studies have been positive -- an indication of just how strong the connection between calcium and bone health really is."
Even more importantly, Heaney cites nearly 50 recent randomized, controlled trials in his report that provide conclusive evidence that calcium helps prevent bone loss and fractures, a painful and debilitating problem for 1.5 million women each year. Many of these studies specifically used dairy products as the calcium source. (Calcium supplements are often used in research studies to help gain greater control, yet health professionals recommend food sources -- like dairy foods -- as the preferred source of calcium.).
Heaney said these reports far outweigh any observational studies that are speculative and do not show a causal relationship. "You need to look at the entire body of evidence -- not a single study that fails to find what well-designed clinical investigations have shown.
"Dairy foods play a valuable role in the diet, and it's extremely difficult to get the calcium you need without milk or milk products. Their role in building and maintaining strong bones is well documented," asserts Heaney.
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