After
reading Allen and Wiley’s Evolutionary Perspective on Cow’s Milk Consumption
and Health, I realized that, you know what, I still like milk. So much so, that
I “got milk” to write this post.
As a 5’9”
North Indian gal, drinking milk has never been a problem for me physically. I was
quite intrigued to learn that this was because of an innate predisposition of
lactase persistence. Yet, despite coming to understand the science behind the
evolution of lactose, I admit to subjectively reading the studies and comparing
them with my own experiences. Wiley distinctively defines the weak relationship
between milk consumption and growth as in Danish children (Figure 5-2)
emphasizing that in more developed countries, little to no effect was created. A
stronger correlation was seen when a calcium-deficient population was tested.
Maybe it’s my mom’s voice in my head, but “she made me a tall girl by making me
drink two milkshake glasses of milk everyday”. And up until now, I believed
her. Not only is the relationship flimsy, but, based on a US study conducted (p
124), nonexistent among girls! Nonetheless,
there’s no doubt that in adequate moderation, milk provides many nutritional
benefits. To some degree I find the implications of cancer and cow milk
overstated, but pertinent to understanding the relative novelty of dairy
products as a staple in the human diet. Whether cow, goat, sheep, soy, almond,
or coconut, too many bio-cultural factors play a role in the action of chronic
diseases.
So there must be a more biological
reason why not only cow, but dairy consumption has steadily been increasing the
past one hundred years or so, right? In my opinion, yes. And, I cannot explain
myself without referring to the evolution of the human diet. As surprised as I
was to see a whole chapter devoted to cow’s milk, I was more surprised on the
short explanation of diet and nutrition provided in the text as it plays a
large part of human evolution. But, this idea of adaptive taste preferences and
aversions made me take note of the strength of all five senses and how they are
capable of widening the “breadth” of foods humans consume. The age of
agriculture and domestication introduced an entire new pallet of taste
preferences in order to maintain a proper diet. The domestication of animals
and the increase in dairy consumption led to stronger bones, particularly the
teeth (http://milk.procon.org/view.answers.php?questionID=000977)
promoting oral health. However, this revolution forced an irreversible change
on the way humans consume food. Before the agricultural revolution, hunters and
gatherers often ate hard, thick food which evolutionarily provided them with
longer skulls. As food become more cooked and soft, skull and jaw sizes shrunk,
more quickly than growing dentition. Ultimately this led, is still leading, to
a “rise in occlusal abnormalities and malocclusion” (http://jn.nutrition.org/content/133/11/3893S.full).
And, it hasn’t become better; despite an increase in milk consumption and its
calcium’s benefit on preventing cavities, teeth decay is at an all-time high.
And, oral health is reflective of an individual’s overall health, reiterating the
subpar modern diet the modern world has fallen victim too.
In the end, I still like milk, even though it may not
be natural, but it’s just another adaptation humans must evolve to as well as
numerous other dietary and nutritional changes.
After reading this post, I'm glad to hear that although that milk doesn't show any real benefits of significant growth, it does help keep our teeth healthier! Milk has some nutritional benefits as well. At least all those times our mother's told us to drink our milk when we were little didn't go to waste. Studies have found "no statistically significant relationship between calcium and growth in height, regardless of whether calcium is supplied as a mineral supplement as a milk derivative (p.124, Evolutionary Medicine & Health)." I think this is what really disappointed me. Being a short guy, I had always relied on the "magic" of milk to work on my bones and somehow give me a significant height change during puberty. This expectation had never come and now, I'm left with this 5'1 build that I'm still (somewhat) hoping to grow out of. At the same time, I'm kind of happy that there isn't really a correlation between milk consumption and growth. I've ignored drinking milk daily for most of my life (except my childhood), and always wondered if I had drank more that I would I have grown taller. Now, I know that height is largely influenced by genes and other factors, not only just by how much milk we drink everyday.
ReplyDeleteI agree with you that I still like milk even after the readings for this week. I prefer the taste of it when I'm eating cereal or when I'm looking for something to couple with my desserts. But, the fact that there is still an increase in tooth decay despite the oral benefits shown from milk consumption is frightening. Considering the unhealthy fast foods that our society has succumbed to, it is hard to say that we can match the healthy diets of our ancestors.
Manmit...you have written a great article. I agree completely with you and Jose and I would never give up milk. My parents were under the same misconceptions as yours were thinking that milk will make you taller. Like Jose said, there is no real significant data that can backup milk consumption and an increase in growth and height. Luckily my genes have given me the great opportunity to grow over 6 feet.
ReplyDeleteTo address another side of the great milk debate, milk can also be harmful to you in the way of IGF-1. IGF stands for Insulin-like Growth Factor. It is the most abundant growth factor in bone. The levels of IGF-1 in the body can be positively correlated with the ingestion of milk and height (pg 124. Evolutionary Medicine and Health). IGF-1 is also responsible for increasing cell division and inhibits apoptosis (pg 131. Evolutionary Medicine and Health). Anytime cells are encouraged to divide and the quality control of their products has been diminished, the first thought is cancer. This means that the consumption of milk can increase the risk of cancer.
Another statement was made about oral health in Manmit’s post. Human’s tooth enamel is not made for highly corrosive organic acids that we ingest every day. Long before humans, an enormous event occurred in the evolution of mammals. Big mammal grazers used to feed on grasslands that were full of C3 grasses. This kind of grass had a low silicone concentration making thicker enamel in order to masticate to be unnecessary. Eventually the grass evolved into C4 grasses and increased its silicon concentration causing for the enamel in many animals to degrade and for them to starve to death. Some animals including mammals adapted and grew thicker enamel and were able to live on.
I wanted to end this post with some history that I learnt in my GEOL 143 class. Humans had to overcome many obstacles in our past in order to be here today.
I can agree and disagree with your postings (But this blog is well thought out, and well written) In chapter 5 Cows Milk Consumption and Health by Andrea S. Wiley is very insightful, and I learned a host of new things from this article like milk digestion, and absorption via enzymatic lactase (I didn't know that this was the only thing that can actually break down mild). I agree with you all above in a since that I will never give up my milk consumption, even though I am an un-Dx lactose intolerant or lactose persistence individual. Even though I love the taste of milk, I also try to drink other products that are similar to milk, like Pure Almond Silk milk. Even though in the conclusion their was a statement that their is no evidence to actually identify if milk increase growth rate, I personally believe its an overall lifestyle with healthy nutritional intake, as well as genetics playing a huge role in growth and development.
ReplyDeleteManmit stated, "The domestication of animals and the increase in dairy consumption led to stronger bones, particularly the teeth (http://milk.procon.org/view.answers.php?questionID=000977) promoting oral health" I agree with you, and I do believe that our consumption plays a role in our bone structure and development. Our body is changing with the environment, and as long as the environment change, our body will do the same to adapt. I agree with you guys above when you guys said the increase intake of sugar, and acidic foods can cause cavity as well as the lack of proper oral care.
Random: I'm really interested in the outcome of hight in the future in areas of the world that increased their intake of milk to grow in hight like China and Thailand.
~Are we really the only mammials that consume milk into adult hood, and is that a little concerning?
~Why does EVERYTHING cause cancer?
Final thought: Dairy has a host a benefits, some proven and some not. But what we do know is that milk can be used in any many ways like backing, making yogurt, making cheese, and drinking pure milk consumption.