March 7, 2005 -- A newly published study shows dairy foods have little to do with building strong bones in children and young adults. But a dairy industry spokesperson says the findings are tainted by the biases of the researchers.
The review of previous studies, published in the March issue of the journal Pediatrics, was conducted by the Physicians Committee for Responsible Medicine. The group is best known for opposing animal research. It is also strongly pro-vegetarian and advocates elimination of all animal products, including milk, from the diet.
In a release issued Monday to coincide with a Washington, D.C., news conference, the group blasted new government dietary guidelines that recommend drinking three cups of fat-free or low-fat milk a day.
A serving of dairy is equal to:
- An 8 oz glass of milk
- 8 oz of yogurt
- 1.5 oz of natural cheese (such as cheddar)
- 2 oz of processed cheese (such as American)
Low-fat or nonfat dairy products have as much, if not more calcium, than whole dairy.
"Under scientific scrutiny, the support for the milk myth crumbles," the statement reads. "This analysis ... shows that the evidence on which the U.S. dairy intake recommendations are based is scant."
Nutritionists Go Head to Head
Of 37 studies reviewed, 27 were found to show no relationship between dairy or dietary calcium and bone health in children and young adults. The remaining studies found only a small association.
The researchers concluded that physical activity early in life appears to be a stronger predictor of bone health than dairy consumption.
"From my perspective as a nutritionist I think it is really important for parents to understand that milk is not a necessary food for children," study researcher Amy Joy Lanou, PhD, RD, tells WebMD. "If children can't drink milk for health or other reasons their bones are going to be just fine."
A nutritionist with the National Dairy Council says she couldn't disagree more.
"There is a clear positive link between calcium and dairy and good bone health," Deanna Segrave-Daly, RD, tells WebMD. "No one food is a magic bullet for preventing osteoporosis, but including calcium in the diet has been shown to be helpful down the road. It is part of an overall healthy lifestyle that includes physical activity."
Segrave-Daly says the studies reviewed by Lanou and colleagues paint an incomplete picture of the science regarding calcium and strong bones.
Dairy: More Than Calcium
But Wisconsin pediatrician Frank Greer, MD, says the science is not as clear as the dairy group suggests.
On its web site, the Dairy Council cites reviews done by its own researchers showing an overwhelmingly positive association between eating calcium-rich foods and bone health.
"(Studies) indicate that milk intake during childhood and adolescence is associated with greater bone mass and protection against fractures in later years," the Dairy Council's bone health summary states.
Greer tells WebMD it is not clear if calcium intake during childhood and adolescence has a long-term impact on bone health.
"The thinking has been that if bone mineral density is as high as possible in adolescence then that will help protect against osteoporosis when someone is 65," he says. "But we really don't know if that is the case."
Greer says physical activity may be more important for promoting good bone health than calcium intake. Heredity may be the most important single predictor of all.
"No one can tell you unequivocally which of these three things is most important for preventing osteoporosis," he says. "It is not clear if calcium intake in early life influences bone density in women with strong hereditary risk factors."
But Greer says he supports the new government guidelines calling on Americans to drink more milk. He even serves as the American Academy of Pediatrics representative for the Dairy Council's "3-A-Day for Stronger Bones" campaign.
"You get a lot more from dairy products than just calcium," he says. "It is our major source of vitamin D in the diet and a good source of vitamin A and potassium. We know that children and adolescents are drinking a lot more soda than milk, so anything we can do to change that would be a good thing."
Calcium From Veggies
An 8 oz glass of dairy contains about 300 mg of calcium. But if dairy isn't your thing, you can get your calcium from vegetables.
These vegetables have the same amount of calcium as a glass of milk:
- 1 1/2 cups of cooked kale
- 2 1/4 cups of cooked broccoli
- 8 cups of cooked spinach
How Much Calcium Do You Need?
The amount of calcium you need is based on your age. Calcium requirements are especially high in older people due to the increased risk of the bone-thinning condition osteoporosis. However, research suggests that building bones at an early age and keeping them strong is vital to having strong bones as you age.
|Recommended Calcium Intake|
|0 to 6 months||210|
|7 to 12 months||270|
|1 to 3 years||500|
|4 to 8 years||800|
|9 to 13 years||1300|
|14 to 18 years||1000|
|19 to 50 years||1000|