16 May, 2013

thought for food. part 1

I've been mulling over the idea of writing a more substantial post about my thoughts on food for a while now. Finally the combination reading tweets from the Nutrition and Health Conference at the University of Arizona College of Medicine, hearing about Michael Pollan's latest book, and a few integrative medicine conferences I've been involved in recently has pushed me to do it. My plan is to break this into two posts: one about what we should eat, and a second about how we should eat.

There's almost no need to even say that we are constantly bombarded with different theories regarding what we should eat. The diet industry has been around for decades, and now the internet gives us access to a near-infinite number of theories about which foods will increase our risk for heart disease, which to avoid to 'lose belly fat', and which to eat if we want to stay young. I think there's actually a lot more to this than people trying to make money. The rates of obesity, diabetes, and cardiovascular disease (CVD) have grown to atrocious levels, affecting people of all ages and socioeconomic statuses. There's a lot at stake here, and I’d like to think we all know that on some level. The problem is that we want a quick fix - turmeric and garlic to fight cancer, veganism to lower cholesterol, raw milk to erase allergies. Even those who are willing to make some sacrifices want a clear-cut answer to health. Ian often asks me which nut is healthiest, or if I could make him some sort of smoothie with all of the healthiest ingredients possible. It doesn't quite work that way, though. Pollan does an excellent job of explaining the downfalls to this route of "nutritionism" in his book An Eater's Manifesto. When we reduce food to it's parts, or try to reduce our needs to a formula, something goes missing. That being said, I completely understand and share in this desire. Navigating the world of food health blogs can be as confusing as the supermarket.

Here is the huge divide in the foodie movement as I see it. [Sorry, I'm going to over-generalize a bit.] On one extreme we have Vegans. The Ornish Spectrum diet is a prime example of this school of thought. It keeps fat down to 10% of your total caloric intake and eliminates animal products (with a few exceptions). Instead, there's an emphasis on vegetables, whole grains, and legumes. In concert with exercise and stress reduction techniques, Dr. Ornish's research indicates that this program may actually reverse CVD. Closely related are Dr. Weil's Anti-Inflammatory Diet and the often touted, though less defined, Mediterranean diet.

On the other hand is the Traditional Foods revival, which is where I’d place the popular Paleo Diet. Here, the emphasis is on grass-fed meats, whole fat (often raw) dairy, sprouted grains or no grains at all, and fermented foods like sauerkraut and kombucha. It seems like gluten-free diets can overlap with either of these branches, whereas the Gut and Psychology Syndrome (GAPS) diet seems to fit better with the latter. To be fair, I don't know nearly as much about this line of thought. But there is research out there indicating that full fat dairy may also help to reduce CVD. The Weston A. Price Foundation is a big name in researching and promoting this type of diet, and they have some really interesting studies to show for it.

But how can this be? Two diets that seem so different at first glance: one focuses on eliminating animal products, the other focuses on eating more, but better, animal products. Let's start by looking at what they have in common. The most obvious thing is the elimination of junk. Nobody is talking about dunking Oreos in their raw or soy milk. Prepared and processed foods account for a lot of the bad stuff in our diets: preservatives, coloring, extra salt, extra sugar, and refined grains. It's amazing how much of this we eat without realizing it - even plain old butter often contains "natural flavor." (Shouldn't it just taste like butter all by itself?) Aside from getting rid of all the non-food in our food, eliminating processed items also cuts down on the simple carbohydrates in our diet. This is a really big first step to eating better. Carbs (bread, pasta, potatoes, crackers) are essentially converted to pure sugar in our diet, so in some ways you can lump them right in there with soda, cake, and ice cream. Without fiber and protein to balance them out, they send our blood sugar level through the roof, forcing our body to secrete loads of insulin and stress hormones to combat all that sugar, and setting us up for developing diabetes. It also augments the immune response, causing some normal protective processes to progress to the point of unnecessary inflammation. Most people have heard of some of inflammation's deleterious health affects by now, like arthritis, irritable bowel disease, and various autoimmune disorders, but it's also being linked to a lot more. In fact, inflammation seems to be turning up as a key player in major chronic illnesses like stroke, heart disease, and even depression. A lot of this research is still in the works, and I don't know of any good studies linking diet with inflammatory markers and a particular chronic disease, but I won't be surprised if we discover that inflammation plays a much larger role than we now know. It's exciting to think about, in a nerdish kind of way.

The second big thing these two ways of approaching food have in common is a lot of fruits and vegetables. I’m still shocked every time a patient tells me he doesn’t like vegetables. There are so many of them! and so many ways to prepare them! How can you possible not like any of them? Hopefully, if you’re reading this, you already know that fruits and vegetables are delicious packages of vitamins and phytonutrients. If you’re not convinced about any one particular produce item, just look it up on this site. They also have lots of fiber, and veggies are low in calories, so there’s no need to limit your intake like you do with other food groups. If you’re not convinced that you should be eating at least 5 servings of fruits & veggies daily, e-mail me and we’ll have a chat.

Finally, what I’m really excited to talk about, is why I think the Vegans and the Traditional Foods folks might both be correct, why both might offer really good advice on what we should eat. Perhaps the link is how we digest and process foods, and it’s all largely dependent on our normal gut flora. There’s been a lot of talk about the importance of probiotics for a variety of reasons, and this is where the fermented foods come into the spotlight in the Traditional Foods diets, so it’s something I’ve thought about casually for a while. I’ve also been fascinated by what I’ve learned about our normal intestinal flora (the bacteria that always live in our gut). But when I read the article by Tang et al. in the New England Journal of Medicine about intestinal microbial metabolism and cardiovascular risk, a few light bulbs lit up. There are two parts of the study, and I’m going to go ahead and explain it in a bit more detail than some might care to read. You see, this is the kind of research that fields like nutrition and integrative medicine need, because it’s so important to say that these lifestyle recommendations are evidence based. The “n” or number of participants is small, but I think the design is fantastic. So, here we go:

For the first part of the study, 40 healthy adults were given a dietary phosphatidylcholine challenge, i.e. they ate two hard-boiled eggs. Phosphatidylcholine is found in egg yolk, and it’s a major constituent of all our cell membranes. The closely-related choline is found in meat. Bacteria that live in our intestines metabolize phosphatidylcholine to trimethylamine-N-oxide (TMAO). After eating these eggs, researchers measured the amount of TMAO in the subjects’ urine and blood. Then, six of the subjects were given a one-week course of antibiotics (500mg each ciprofloxacin & metronidazole), to wipe out the intestinal bacteria. (This is the same process by which taking antibiotics can give you diarrhea.) They repeated the phosphatidylcholine challenge after finishing the antibiotics, and then a third time one month later after the intestinal flora had presumably restored itself. They found that the course of antibiotics significantly lowered, indeed, nearly erased, the amount of TMAO measured. After one month, these levels came back up. This study demonstrates that our intestinal flora is responsible for producing TMAO.

The second part of the study enrolled 4007 adults who were undergoing elective cardiac catheterization without evidence of ongoing heart attack, and measured the TMAO level in their blood. These subjects were followed for three years, to see who had adverse cardiovascular events. Those who did were more likely to have many of the expected risk factors, as well as a higher baseline TMAO level. Even after adjustment for traditional risk factors, a higher TMAO baseline level was still a significant predictor of major adverse cardiovascular events.  Further, it proved to predict risk on a graded scale, rather just a simple high or low cut-off, even for subjects in the lowest quartile of other risk factors.

To summarize without so much jargon, though this may also make it sound more definitive than most scientists like:
·       Phosphatidylcholine is a substance found in eggs. Choline, found in meat, is very similar.
·       It’s not all bad; our body needs it to some degree.
·       Some of the bacteria in our gut convert it to TMAO.
·       It doesn’t get converted to TMAO without those bacteria.
·       More TMAO = higher risk of heart attack or stroke.

Therefore, one would think that more meat and eggs also equals higher risk of heart attack and stroke. The authors give a really nice conclusion in their discussion of what this might mean for dietary recommendations.
“Our data suggest that excessive consumption of dietary phosphatidylcholine and choline should be avoided; a vegetarian or high-fiber diet can reduce total choline intake. It should also be noted that choline is a semiessential nutrient and should not be completely eliminated from the diet, since this can result in a deficiency state. However, standard dietary recommendations, if adopted, will limit the intake of phosphatidylcholine- and choline rich foods, since these foods are also typically high in fat and cholesterol content. An alternative potential therapeutic intervention is targeting the composition of the microbiota or biochemical pathways, with either a functional food such as a probiotic or a pharmacologic intervention.”
The speculation that I would like to make, and this is of course reaching quite a bit, is that the “functional food” component of the Traditional Foods movement – raw milk & yogurt, fermenting – does in fact change the microbiota or biochemical pathways. It would be fascinating to do a similar study as the first part of this article – phosphatidylcholine challenge with 3 arms: a control, a group treated with antibiotics, and a group eating a reasonable amount of these foods on a daily basis for some period of time.

But we’re not there yet, so where does that leave us? I think Aristotle got it right millennia ago with the Golden Mean. Life is about flux and trying to find balance, and this applies to diet too. There are a few things about which we can walk away from all of this with certainty, though. The first is that we should keep prepared, processed foods to a minimum. Anything that comes in a box or a bag with a long list of ingredients, especially if you don’t know what some of those ingredients are, should not make up a large percentage of your diet. The same thing goes for inflammation-provoking carbohydrates and added sugars. The second thing is that we should eat more fruits and vegetables. Everyday. Period. The beauty of this is that once you start eating this way, your body won’t ever want you to go back.
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