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Tuesday, July 5, 2011
Diet and Nutrition
Pros and Cons of Dairy Consumption
I know this may be asking a bit much of you, but this article proposes some very controversial items related to dairy and calcium. Would you mind giving me(us) your thoughts on whether this is mostly false claims or facts...Thanks
I am concerned about dairy comsumption, since I currently choose to eat very little dairy.
Thanks for your question. This is indeed a controversial topic. After reading the article written by Emily Yofee, my professional opinion is that I will still recommend dairy foods for calcium. They have been found to contain the highest amounts of calcium and are the most absorbable forms of calcium. For those individuals that do not drink milk or are lactose intolerant, there are fortunately other options. Green leafy vegetables, tofu, sardines with the bones, calcium fortified juice, dried beans and calcium supplements also provide calcium for the body. The fact that other cultures do not drink milk may or may not be a factor in bone loss. Bone loss is not that simple. It is true that the body absorbs more of a nutrient when it is in a state of deficiency (such as in iron or calcium deficiency). And, it is also true that smaller doses of a nutrient are better absorbed than larger doses. This is the reason nutritionists and other health professionals recommend taking calcium or iron in smaller more frequent doses. However, calcium is needed in the blood as well as the bones. One of the functions of calcium is muscle relaxation. If there is insufficient calcium in the blood, the body will leach it out of bones, therefore demineralizing bone, leading to bone loss. The critical time frame for women in preventing osteoporosis is from the ages of 14 and 25. This is the time when most of the calcium is being deposited in bones. No wonder we worry about soft drink consuming teenagers that despise milk! After this critical stage, the body will then break down and reabsorb calcium as needed in the bones. Your body also needs adequate protein, vitamin D and magnesium, as well as weight bearing activity to maintain bone mass. The lack of bone loss in other non-milk drinking cultures may be due to exposure to sunlight, physical activity, AND intake of calcium and other nutrients. In addition, heredity, body weight and estrogen are also strong predictors of bone loss. It is too simple to blame the dairy industry or calcium intake for bone loss. In addition, the researchers comparing rates of osteoporosis in American women to osteoporosis in other cultures are not comparing apples to oranges. There are physical differences in these populations (such as different hip structure of Chinese women), as well as compounding variables such as other dietary factors (magnesium, protein, vitamin D, sodium intake) physical activity, smoking and other lifestyle factors. It is true that Americans consume more animal protein than they need, and that this may lead to bone loss. Perhaps it is due to all the high protein fad dieting in our culture? In addition, our society consumes more sodium than it needs, which can also contribute to bone loss. Also, phosphorus containing soft drinks and phosphorus and sulfer from protein foods can lead to calcium loss in the bones. Who is to blame? Health professionals can only provide research and recommendations to consumers. Beyond this, it is an individuals choice. The amount of dairy foods most health professionals recommend would not be excessive in protein. Three sources of dairy foods daily provide about 24 grams of protein. The RDA for protein is about 55 grams for women. Calcium losses do not occur until protein intake exceeds 100 grams per day. Adequate protein is needed for calcium absorption, so we can`t limit it too much in our diets. In addition, health professionals recommend only 2 three ounce servings of meat or other high protein food per day (which provides about 42 grams of protein). The rest of our dietary protein comes from grains and vegetables, which should not be detrimental to our bones. It is difficult to deny or ignore the valuable research that is devoted to developing dietary guidelines and RDAs for nutrients. If high calcium intake were contributing to bone loss, I seriously doubt that the majority of health professionals (including the NIH) would push for higher calcium intakes. The amount currently recommended has increased from 800 mg per day to 1000 mg or higher per day. For more information on calcium and bone loss, browse previously answered questions on this site, or check out the osteoporosis site of Netwellness.
Lisa Cicciarello Andrews, MEd, RD, LD
University of Cincinnati