Saturday, March 7, 2009
Eating Healthy: Part 6 - Moo-ving on to the Dairy Group
The USDA's Food Pyramid (click here) and the American Academy of Pediatrics (click here) both stress the importance of consuming 3 servings (for most children and adults) from the "Milk" or "Dairy" group each day. Milk and foods from the dairy group provide Calcium and Vitamin D - two very important nutrients. Prevention magazine calls vitamin D the new supervitamin (see here) and a lot of us (especially 'round these parts) are vitamin D deficient. In a study published here on the American Heart Association website, dietary intake of dairy products reduced the risk of developing high blood pressure whereas calcium and vitamin D supplements alone did not produce the same benefit .
---However, as I was doing my research I discovered that drinking milk (especially cow's milk) in adulthood is not universal to all cultures. (see here) In fact, in many cultures including those renowned to be the healthiest in the world, (a couple are mentioned here in this article) people do not consume milk past infancy and do not consume large amounts of cow's milk as we do in the US. So, is consuming milk the best way to obtain these nutrients and prevent diseases such as osteoporosis? Does milk really "do the body good"? In "Staying Health with Nutrition" (2006) (click here) the author recommends decreasing dairy intake from what is recommended on the Food Pyramid. Even the Harvard School of Public Health (in this article) is not convinced that consuming 3 servings of milk a day is best.
---Others have agreed that dairy consumption is overemphasized in the North American diet and on the USDA Food Pyramid. Many physicians would agree that some children and adults would benefit by altering their diets to limit or exclude dairy products. There is anecdotal evidence that eliminating casein (milk protein) from the diet may significantly improve behavior in children diagnosed with autism spectrum disorder. Scientific research is looking into that link.
---Other children and adults are unable to digest and absorb lactose (milk sugar) due to deficiency of the lactase enzyme which results in gastrointestinal symptoms. According to medicinenet.com, "The most common cause of lactase deficiency is a decrease in the amount of lactase that occurs after childhood and persists into adulthood, referred to as adult-type hypolactasia. This decrease is genetically programmed, and the prevalence of this type of lactase deficiency among different ethnic groups is highly variable. Thus, among Asian populations it is almost 100%, among American Indians it is 80%, and among blacks it is 70%; however, among American Caucasians the prevalence of lactase deficiency is only 20%."
---Others believe that the amount of calcium and vitamin D that an individual requires (therefore the importance of dairy) may depend on factors such as protein intake (high protein diets require higher calcium intake) and sun exposure (which is important for the synthesis of vitamin D). See this link again for more about osteoporosis in different cultures. Maybe factors such as these would explain why people in certain cultures can be very healthy while consuming very little or no milk.
---So what can we make of all of this? I will say that personally I love milk. I would usually prefer a glass of milk over a glass of water. And without consciously planning out a diet plan, I would have no problem drinking milk and meeting the 3 servings of dairy a day (I like yogurt also). However, lately, I have been leaning toward making sure that I do not have more than 3 servings a day (preferably only 2) for a few reasons.... First off, I am not completely comfortable with the way that milk is produced. In "Staying Healthy with Nutrition" the author explains his concern that cattle are commonly injected with estrogen to speed up growth and antibiotics are also often added to their feed. We can be exposed to these drugs and hormones in this way. And, as mentioned in the link to the Harvard School of Public Health site, "Some researchers have hypothesized, however, that modern industrial milk production practices have changed milk's hormone composition in ways that could increase the risk of ovarian and other hormone-related cancers. (16) More research is needed."
---Secondly, while there appears to be some evidence that drinking milk and eating yogurt regularly can help in weight loss, milk and other dairy products do contain calories and may contain significant levels of saturated fat. This chart illustrates the difference in calories in whole milk vs. low-fat vs. skim.
---Thirdly, symptoms of mild milk intolerance may be mild and include but not limited to symptoms such as abdominal bloating, excessive intestinal gas, excessive rumbling, nausea, diarrhea, constipation, or abdominal cramping. From my understanding, it appears there are degrees of lactose intolerance and even a person who has significant lactase enzyme to digest milk may have symptoms if large amounts or "too much" dairy is consumed.
---In the last couple months, I have discovered that vanilla rice milk is very delicious. Others have preference for soy milk or almond milk, but I like the taste of rice milk the best and I felt rice milk may be the best choice for me due to the "estrogen factor". Rice milk does not contain casein or lactose and is lower in phosphorus than cow's milk. (Too much or too little phosphorus may play a role in development of osteoporosis.) So, my decision to try to decrease cow's milk by alternating it with rice milk and yogurt and other vegetable sources of calcium, is really because I think researchers and medical doctors are still trying to figure all of this out. And, until then, by varying foods, I think that diversifies the nutrients that are being consumed to hopefully lessen the chances of an excess or deficiency in any one particular nutrient. And, not that I had any reason to suspect lactose intolerance, but I wanted to see if I noticed any change in mild symptoms that are often hard to pinpoint (basically just generally feeling better) when I limited my consumption of cow's milk to only 1-2 servings a day rather than what was sometimes probably more than 3 (I am not saying to just avoid dairy all together unless you have discussed this with a physician and dietician - I still usually consume 2-3 servings of dairy all together each day just not all as cow's milk). I am still trying to decide if there is any difference, but I think possibly I do feel better (maybe it is related to something else though?).
---So, in conclusion...getting nutrients such as calcium and vitamin D is very important. Three servings of milk and dairy may be the best way to get those nutrients for most people in the US - that is what the USDA Food Pyramid recommends (that is exactly 3 servings however, not a minimum recommendation like when we were talking about fruits and vegetables). Three servings of milk/dairy products may be especially important for growing children and teenagers. But, if you have any undiagnosed symptoms, high risk for osteoporosis or certain diagnosed disorders, there may be better alternatives, and you should discuss these with a physician or dietician to develop a nutritional plan. Don't try to diagnose yourself or make major dietary changes like excluding a food group without talking with a physician or dietician. Hopefully, research will continue to look at the role of milk/dairy products in the diet and we will have more answers to some of these questions in the future...