Monday, March 4, 2013

I'm not a nutrition expert, I just play one on the radio.

One of my favorite local radio programs/podcasts that I like to listen is KERA's Anything You Ever Wanted to Know.  People call in and e-mail in with all sorts of questions on all types of topics; from where to find restaurants that serve a particular cuisine to why the sky turns green before a tornado.  Sometimes you even get questions related to food/food science/nutrition, and since it's local people just trying to help each other out, sometimes the answers are good, and sometimes they induce me to yell at the radio/listening device.  (The latter does not seem to cause any harm while alone in the car, if it's done in the office or in the house co-workers and pets find it disturbing).   Last Friday's show did induce a bit of yelling, but since I was in the car driving to a patient's house, no co-workers or pets were disturbed at the time.

The question that started it all went something like, "Why is the expiration date on the organic milk farther out than the expiration date on conventional milk?"  Turns out this question had been asked on another show, and there was someone who called in with a legitimate answer: organic milk usually has to travel farther so producers have to subject it to a process called ultrahigh temperature (UHT) processing or treatment.  More details on the process are in this excellent article published on the online Scientific American.

Since most listeners are quite eager to show off their knowledge and/or help, however, usually one answer is not enough to satisfy, so a few minutes later there was another answer.  It went something like: "The reason that organic milk lasts longer is that it all comes from grass fed cows and you don't have to worry about the same bacterial issues.  There is a farm in such-and-such a place that sells raw milk, and it's better for you because it has the 'good bacteria' in it.  Call this lady who owns the farm and she will tell you more about it....."  At this point, I knew any of my friends who were listening knew that they were probably going to a) hear my head explode over the amount of misinformation sprinkled throughout that answer and b) get to read a blog post after I put my head back together.  Ready?

To begin with, if you read the linked article you will see that all "organic" means when it comes to milk is that the "farm the milk comes from does not use antibiotics to fight infections in cows or hormones to stimulate milk production."  Period.  So, some milk labeled organic might still come from cows fed grain instead of grass and the cows might also be stabled instead of being "turned out to pasture."  In the case of the farm the caller was talking about, it sounds like the farm had cows that were both hormone free and pasture/grass fed, but seeing "organic" on the label at your neighborhood grocery store or "specialized" store (e.g. Whole Foods or Sprouts) does not mean that you are getting grass fed beef.

Second of all, is the milk from grass fed cows safer?  Possibly.  Apparently, when cows are fed grass their digestive tract tends to be less acidic and bacteria like E. coli does not survive as long and is easier to kill off.  Cows that are allowed to roam in the pasture are less likely to come in contact with fecal matter which can contaminate both meat and milk.  Is there still enough scientific data to say that raw milk is perfectly safe?  Not really, at least according to the limited amount of studies done by Cornell more than ten years ago. (Link)  Of course I can't help but think of an acquaintance of mine who apparently got tuberculosis from raw milk several years ago, and I think it's also worth it to point out how the deaths from once common milk-borne illnesses have plumeted.  If you do choose to consume raw milk, make sure you do your homework and get a chance to visit the farm and interview the farmers, and you can also check this website to see what kind of regulations are in place in your state, particularly before deciding to feed it to children.  And if you are pregnant, or have a lowered immune system from chemotherapy or HIV, do you really want to take the chance?

Is the organic/raw/grass fed milk healthier like the caller claims?  Well, I'll need to break down that question into different parts.  As far as "organic" (i.e. hormone free) milk being healthier, I will have to admit that hearing about the use of "hormones" does make me feel queasy, but since I'm a scientist I also have to go with the data, and the data says there isn't a difference (Link).

 As far as raw milk being better for you because it has the "good bacteria" in it, this claim is unfounded, and even if you have raw milk cheese/yogurt made from having "good bacteria" added to it, remember I've written more than once about how probiotics provide only a limited benefit.    I've also heard other people talk about how some people don't tolerate raw milk because they are just not "used" to the "good" bacteria--unfortunately instead of just getting a case of the runs you might also wind up with kidney failure or dying, and I personally do not want to chance it.  I have also read some claims that raw milk has a higher vitamin content and more "enzymes" left intact, but I have trouble finding good studies to back that up.  Instead I found a lot of conspiracy theories about how "they" don't want you to know about the benefits of raw milk, but not a lot of good evidence.  The other thing that I found interesting is that were a lot of "arguments from ancient wisdom" fallacies (Cleopatra used milk to make her beautiful!), and that the same group of people who were advocating for the use of raw milk were also against the use of grains of any form.  The main reason for that argument was grains were only introduced into the human diet about 10,000 years ago with the advent of agriculture; do they not also realize that the use of dairy would have come into play about the same time?  Why are grains bad, but dairy is not?  (Pardon me, I'm going to take a break to laugh over the mental image of paleolithic man trying to milk an auroc).  Never mind that the ability to digest lactose after the age of three or four years is rather a unique genetic trait of western european ancestry.

Now for part three of the multipart question, is the grass fed milk any healthier?  For those of you who able to tolerate cows milk (I am not), grass fed cow's milk actually does seem to have a higher content of conjugated linoleic acid (CLA) which is one of those fats that seems to be anti-inflammatory and usually billed as "heart healthy" for that reason (Link). And if you have small kids, they need that fat to support their growing brains period.  Let's all remember, however, that the amount of something you consume has a large impact on your health.  One glass of whole milk has ~150 calories and roughly 13 grams of carbohydrate.  If you have diabetes/pre-diabetes or some other insulin resistant problem, you will still have to count those 13 grams toward your total carbohydrate intake.  Of interest to people with milk protein intolerances like yours truly, sometimes the breed of cows used on grass fed farms actually produces a different type of protein called A2 casein (not all grass fed farms are this way--you'll have to ask if they did DNA testing).  It is possible that the A2 casein may not cause the same type of GI distress as the A1casein which is found in the milk in your average grocery store.  Although this gives me some hope for possibly being able to eat certain kinds of cheese again, I know that there are more studies that need to be done and right now I personally don't want to risk it. (Link)

Take home message--Organic milk might be healthier if it comes from grass fed cows.  More scientific research needs to happen to ensure the safety of raw milk and to ascertain any additional health benefits from it.

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