Sugar, or sucrose is made up of glucose and fructose. Together they have a glycemic index of 65 which is similar to white bread which is about 70. When separated out however they have glycemic indexes of 97 and 23 respectively. The interesting part, though, is that fructose tastes way way sweeter than glucose. So measuring the glycemic index of food through your taste buds and making a judgement based on what tastes the sweetest is fraught with danger.
The theory with the glycemic index is that the higher a food is on the index the more it causes your blood sugar to spike. Spikes in blood sugar is what is supposedly causing us to develop insulin resistance and laying the ground work for metabolic syndrome.
So here we have fructose that tastes incredibly sweet, yet has a low glycemic index value, so presumably causes a smaller rise in blood sugar levels than glucose does. Wouldn't that make it a good thing to eat then?
Apparently not. The story gets stranger. Even though it doesn't trigger blood sugar surges it is the component of sucrose that is driving our propensity towards diabetes. David Gillespie in Sweet Poison postulates that the problem with fructose is that our body just doesn't recognise it. We happily consume it in our table sugar along with glucose and it has a way of by passing all our systems and getting itself into the blood stream by barely registering on the bodily Richter scale. We notice it on our tongues and then later it appears in our blood stream rising triglycerides and turning up as fat. It's like our body doesn't know what to do with it, doesn't quite have the mechanism to deal with it, so it just shoves it off into our cells. And it is here that it starts to cause us the health problems related to diabetes and syndrome X, aka metabolic syndrome.
Loren Cordain advocates a diet free of refined carbohydrates, grains, dairy and saturated fats. Basically it is a high protein diet based on lean animals meats and tons of fruit and vegetables, because this is what our stone age ancestors ate. A typical meal looks something like this: a piece of steak, 2 cups of steamed broccoli, 2 cups of lettuce, 1 cucumber, 2 tomatoes, 1 grated carrot, followed by half a rockmelon filled with diced strawberries That's a lot of vegetable matter. Every meal requires that level of vegetable matter because fruit and vegetable are now your prime source of carbohydrates. Corn and potatoes are not permitted.
So based on this meal, Cordain's take on the Paleolithic eating pattern was that they slaughtered a big animal, butchered it, and then ran around finding a large salad of a wide variety of vegetable and fruit to go with their meat. Now I haven't studied the subject to the extent that Corbin has, but I still wonder whether personal bias has intervened here. I can draw on what I have learnt about the indigenous people in my own country. The gathering part was pretty hard. There were bits and pieces here and there, but they were focused on finding dense sources of food like nuts, berries, seeds and tubers. Some of these required specialist preparation back at camp, some were just plucked and munched on as they went about their business. Meats were seasonal. In certain seasons those with access to the beach would gather and gorge themselves on shellfish. The hunting and eating of the bigger game and trapping of fish were times of plenty. They would have been subject to periods of feast and famine. I don't really see where masses of leafy green vegetable would have fitted into their diet, they just wouldn't have been abundant nor able to pack the nutritional punch they needed.
The other premise of the Paleolithic diet is that over just 333 generations we just haven't had the time to evolve to be able to handle the high levels of refined carbohydrate and sugar currently in our diets. That's why we are seeing so much ill health in the way of chronic diseases. Well evolution works on a principle of survival of the fittest. Our problem is that the refined sugar and carbohydrate diet is not killing us off quickly enough. The chronically ill are healthy enough that they get the opportunity to reproduce. The diet needs to either make them infertile or dead before reproduction age so that those who cannot adapt to the new lifestyle get weeded out. Some people seem to have the metabolism that can cope with a pretty crappy diet of refined carbohydrates and resist chronic disease. Presumably these would be the ones which natural selection would keep, and the majority of us with various syndrome X diseases would get weeded out of the population. Mother nature is pretty harsh.
Again looking at indigenous Australians we can see an example of this. If non- indigenous Australians have had 333 generations to adapt to our change in diet, the indigenous population have had about 10. Now if this diet was bad for us, we would see, you would think, greater evidence of it's impacts on the indigenous people. And guess what? We do. They love the sugary sweet stuff and they are seriously over represented in the diabetes statistics. So if you are nodding your head agreeing that this proves we are not adapted to our Neolithic diets, you also have to accept the premise that as rates of disease are higher in the population that has had less generations to adapt, we must be adapting, all be it slowly. The human body is pretty amazing and can take a serious amount abuse. But if we are adapting then a complete reversal to a Paleolithic diet would be a retrograde step. There were undoubtedly sound reasons why we adapted agriculture to feed us. I would like to examine some of the whys in a future blog.
But for now, I just wonder whether we really need a strict all or nothing approach? I can accept that we ate way more protein and fat, and way less refined carbohydrate than our current dietary pyramid recommends. But being the ultimate omnivore we would have been eating some forms of seeds and starchy carbohydrates when we could get them. Predominately we ate meat, also when we could get it. We couldn't store it, so we had to eat it a lot, and fast if we didn't want to get sick. Similarly, if we came across fruit, we ate the whole lot. We couldn't store stuff and when fruit is in season and is ripe you either take advantage of it and eat it all or miss out on its bounty. This is where I suspect our bodies adapted to not recognise fructose in our bodies. The fruit was so rare yet so important that when we saw it we needed to eat it. The pay off was a sweet treat brimming with essential vitamins and minerals. We couldn't afford to be conservative and have our bodies worry about silly things like saiety. We needed to bypass the regular systems and make sure that we loaded up on this good stuff, and yes to the point of storing some of it as fat if need be. Now we have the situation where sugar is abundant and our bodies are still operating the same way by hiding the fructose component from our saiety registers.
The reason children love sweets so much? It was even more important for them than adults to load up on the fruits and store fat as they were growing. While the harvest of wild fruits was abundant they needed to fill their bodily stores because being smaller with a greater surface area they were more prone to the cold of winter and they needed to ensure that they grew into adulthood in order to reproduce and keep the species going. So maybe that's why evolution hasn't weeded out the sugaraholics yet, maybe they are the ones that have ensured our survival and got us to where we are now.
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