In Part 1, we began the process of distinguishing the difference between a food group and a macronutrient. Carbohydrates (Carbs) are probably the most vilified of the macronutrients. This is probably due to the ubiquitous availability of starch foods throughout human history. For the most part, oils, fats, and meats were the food of the rich. Everyone else ate beans, rice and potatoes.
If we listed the many staple foods: grains, rice, beans, squash, quinoa, potatoes and corn we see a high amount of starch. Remember, starch is simply a long chain of glucose. We all need glucose to live and our primary energy is derived from glucose and stored glycogen or fat (more later).
I want you to know that a carbohydrate need not be fattening, nor lead to diabetes. In fact, Carbohydrates can be very satiating (1) for 4-5 hours after meals. What seems to be the big diversion, where the “bad carbs” come in, is the processing (blending, frying, flouring, pasting, etc) of carbohydrate. When we break down starch too much in the food preparation process, it leads to lots of simple sugars. These are both easy to overeat and can have other deleterious health effects.
Starch digestion begins in the mouth with the amylase in the saliva. The starch begins to break down to glucose. A great way to experience this first hand is to take a unsalted cracker and just hold it in your mouth. You will begin to generate a lot of saliva and as you hold it there, begin to taste sweetness as the glucose is formed. Remember, a termite can do exactly the same thing with cellulose in wood.
From an evolutionary biology perspective, the AMY1 gene that is responsible for making amylase is so important that you have as many as 12 copies of it (2). It was extremely important to our hunter-gather predecessors. While there’s been much put forward on the “hunting” side of the equation, some of the most recent anthropology suggest that the “gathering” side dominated. Underground storage organs (USOs – tubers, bulbs, corms, and rhizomes) played a significant role in our energy management of times past.
Men like the idea of beating their chest and running through the woods hunting and they write a lot of the stories, but gathering is actually a better (less sexy) explanation of our survival. It even allows the elderly to participate productively in the group, even grandmothers would have a significant role in the earliest tribes. Anyone can dig up a potato, they aren’t very fast, and they grow in predicable places.
The naked mole rat is found with archeology of hominid population explosions and points to USOs as a gathered food source. click photo for NPR Story
Many of the early tools used to process USOs were probably made of wood and didn’t survive in the archeological records, but the early Hominid starch crystals in teeth have. Also there are also fossilized populations of mole rats that surge with every human population expansion (3). We’ll also learn that the mole rat has some FASCINATING genetics that impacts thermal loading.
I don’t want to get into the Paleolithic debate. What I want everyone to see is that starch IS an important evolutionary part of your fuel system, but at the same time recognize french fries are NOT the starch I am talking about. Your view of carbohydrate has been jaded since the beginning of diets. In the earliest of diets (Banting) it was simple breads combined with butter/sugar that caused the excess energy to creep in. Processed starch (sugars) of all kinds can lead to excess caloric intake; it’s just easy to digest and pleasurable to overeat, especially when combined with salt and fat.
For today, understand that primary complex carbohydrates: squash, legumes, onions, carrots, whole corn, whole rice, and potato are all good bases of energy. They are satiating ways to make up for caloric deficit, but don’t confuse those items, “items your great grandmother would recognize as food,” Michael Pollan might say, with the “carbs” served at school lunch.
Most importantly understand that many of these “starchy” foods also contain significant proteins with complete compliment of the essential amino acids your body will use to synthesize your own protein. These complex carbohydrates are broken down by amylase to glucose: the fuel for your brain and many cells in the body. If they aren’t consumed with excessive alternate energy sources (like excessive fat or simple sugar), your body will tap into it’s own fat reserves. If too much pre-processing is performed, then you might see increased problems managing blood sugar.
Eating carbohydrate is convenient and pleasurable, and know there is room for “carbs” in your diet if you make the correct choices.
So, when we are putting this all together and I say carbohydrate, I want you to think about these whole, starchy food items that enter YOUR kitchen/cooking reasonably resembling how they came out of the ground or off the plant. Sugar, raw, brown…whatever, is refined. I challenge you to eat the 250 lbs of sugar a year gnawing on sugarcane, however; you might be able to do it with grapes or beets.
Others have commented on fructose, a simple sugar in fruit, and I think there is merit to the issues that come from too many simple sugars, especially highly processed. This likely includes high fructose corn syrup, apple juice, sucrose, agave nectar, etc…). Fruits are not found in nature year round, but USOs are. Similarly, think about what is easily stored (beans vs beets). It’s amazing to hear people rave about “natural agave nectar” (inulin/fructose squeezed from agave) and then begin to lambast the food industry for high fructose corn syrup (fructose squeezed from corn). Yes there are some differences, but we’ll debate it in 5-10 years. It’s all simple sugar to me and best avoided.
These simple sugars are energy without the fiber or micronutrients. Others, like Robert Lustig, have covered the issue of fructose in far better detail than I will, but likely our problem as a nation is probably more related to drinking, for example, too much apple juice, rather than eating too many apples. The same is true of french fries vs potatoes. The larger group health statistics just don’t separate the issues (e.g. apples vs apple juice or fries vs potato) with enough granularity and it is all complicated with saturated fats and other compounding, synergistic concoctions we now call food.
Many energy dense foods are now available year round (like fruits or avocados) and so we must be careful with these foods. We’ll see a similar trend with fats, oils, and nuts.
Starch is a wonderful molecule and has been around for millions of years. Starch is just one bond different from wood. You are designed to eat starch, with back ups systems in place (AMY1). We can identify paleolitic starch in teeth, even knowing the plants that produced it, and so there is nothing wrong with carbohydrate as a food – it highly processing it and combining with other energy-rich processed product that causes much of the issues.
You will inevitably hear more about the amazing work anthropologist, Nathaniel Dominy is doing with starch and USOs. I personally believe the depth and thoroughness of his work will have an impact on what many, like Loren Cordain, believe to absolute. Nate has a very uncanny ability to see past the obvious. For the record, he’s a meat eater, despite what he’s uncovered in the last few years about starch in anthropology.
In terms of the thermodynamics, most natural starches come with a compliment of other micronutrients that are beneficial. These are “energy foods” and so we absolutely CAN lose weight by eliminating them from your diet. I am not suggesting diets higher in fat or protein (atkins, paleolithic, slow carb) cannot be used to lose weight – I am diet agnostic. What I can explain is on whole the overall management of energy, heat (not temperature), that is responsible for your success.
If we stop isolating these foods based on our perceived/suggested notations of macronutrient content and return to simple food, A calorie will be a calorie. Once you learn to recognize what you are consuming at every meal (and snack) you’ll see the results you’ve been after. It doesn’t even take discipline once you understand the underlying principles.
Gauging on the comments/questions, I might dig in a little more (Part 3) on carbohydrate. Eventually I will post the overall biochemistry and some have written asking me to explain the TCA cycle (that complex part in the middle of a Lustig presentation if you’ve seen one). Otherwise, I will move onto fat and catch sugars in the wrap up.
Next week is TEDMED in San Diego. It’s hard to believe a year has past. I’ll probably have at least one update on what I learn there, but will *try* to write two posts on fat before I leave so they can post next week.
(1) Carbohydrates and human appetite, Blundell, JE, et al.,Am J Clin Nutr 1994;59(suppl):728S-34S.
(2) Diet and the evolution of human amylase gene copy number variation, Perry, G.H., et al., Nature Genetics 39, 1256 – 1260 (2007)
(3) Communication/presentation with Dr Nathaniel Dominy, Dartmouth University Dept of Anthropology
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