Deadly Harvest: The Intimate Relationship Between Our Heath and Our Food (21 page)

BIOCHEMICAL CLUES

We turn now to the study of the tens of thousands of chemicals that swirl around our bodies. It is also the study of how they are orchestrated into this incredibly complex system that, day after day, makes our bodies function. It is the science known as biochemistry. A knowledge of how human biochemistry operates will provide us with valuable clues as to what dietary factors fuel the system as nature designed it.

With advancing research, we are realizing just how incredibly complex are the workings of the body. It is a classic case of the more we know, the more we realize how little we know. Biochemists call our body’s biochemistry a “chaotic” system in the mathematical sense. That is, it obeys all physical laws, yet the outcome of any particular action is mathematically impossible to predict. The weather is another chaotic system—even if we knew everything about barometric pressure, temperature, and so forth, there is no way of accurately predicting the weather. We now understand that, when we try to intervene in our body’s operations, we can never predict the outcome with certainty either.

There is a myriad of chemical processes going on in the body all the time. It is mind-bogglingly complex, like a three-dimensional chess game. We just understand that it is an unmanageable network. A very important lesson is this: an action today will sometimes have the opposite outcome to the same action yesterday; it all depends on what other processes are happening in the body at the same time.

To take one example: a teaspoon of evening primrose oil taken yesterday might calm inflamed joints; today, it might make them worse. What causes this disquietingly unpredictable result? It all depends on what else you have eaten in the last few hours. A glycemic food (one that causes blood sugar to spike abnormally) increases the body’s production of an enzyme called delta-5-desaturase. This in turn flips a switch: evening primrose oil now makes chemicals that inflame joints rather than calm them. This is just one of a huge variety of inputs for which we cannot second-guess the outcome.

Indeed, this is one of our central messages: we cannot micromanage our body’s operations. However, this is what people are trying to do all the time, and we end up driving a truck through the delicate minuet being danced by our body’s biochemistry. We meddle in things we only partly understand with consequences that can be the opposite of those intended. I call it the Sorcerer’s Apprentice syndrome. In the 1940 Disney film
Fantasia
, Mickey Mouse knows the magic spell to animate the broom to fetch water from the well to fill up the kitchen sink. However, he doesn’t know the magic spell to make the broom stop fetching water. Result? The broom goes out of control filling up first the sink and then the house with a nightmarish, unstoppable flood of water. The lesson to learn is this: our own body is the best manager of itself—we just have to get out of the way and give it the tools to do the job.

We have known for a long time that some saturated fats are harmful to the smooth functioning of our bodies. Already, the message has gotten through that old friends like cream, butter, and fatty meat are not to be trusted. Health professionals have been proclaiming for decades that we should avoid them. Recent discoveries are dispelling other myths: cholesterol consumption of itself is not threatening to health; cholesterol only becomes a problem when it attaches itself to the artery walls. Why does it do that? One immediate reason is that immune system cells on one side of the wall are trying to pull the cholesterol molecule through from the other side, and it gets stuck. The question is: what provokes immune cells into doing something harmful like that?

In other words, our biochemistry needs to work to a very specific pattern. It has firmly defined characteristics that provide strong clues to our naturally adapted diet. We will now examine four of them to see how they illuminate our understanding of the “Owner’s Manual”: blood sugar control, essential fatty acid hormones, the salt/potassium ratio, and the acid/alkali balance.

Blood Sugar Control and Carbohydrates

People generally understand that carbohydrates are starchy foods like bread, pasta, potatoes, cookies, and cereals. Technically, however, the term
carbohydrate
is much broader: it also includes a whole spectrum of vegetation (such as lettuce, broccoli, and apples) and sugars (such as sugar itself, honey, confectionary, and maple syrup). In fact, carbohydrate molecules are nothing more than glucose molecules strung together in a multitude of different ways. Most creatures, even carnivores like dogs, are equipped to digest sugars and starches. Our bodies can unzip the carbohydrate molecule back into glucose molecules very quickly by using special helpers known as enzymes. Enzymes have the power of speeding up chemical reactions by thousands of times. Other carbohydrates, such as the material that makes plant walls, can take much longer to digest—these are known as “very complex carbohydrates.”

What are Carbohydrates?

Carbohydrates used to be classed as either simple or complex. Simple carbohydrates were sugars and were considered “bad” for blood sugar control. Complex carbohydrates included everything else from starches to broccoli and were all considered “good” since they were thought to be easier on blood sugar control. We now realize that this was too simplistic, because starches aren’t all that complex either and are “bad” as well. In common parlance, starches are still called complex carbohydrates; however, a new category of “very complex carbohydrates” has been created for foods such as broccoli, lettuce, and so on, and these now inherit the mantle of “good” carbohydrates.

The body converts all carbohydrates, sometimes quickly and sometimes slowly (according to their type), into sugar (glucose) in the bloodstream. The body needs to maintain blood glucose levels within very narrow limits, which it does by a seesaw mechanism using hormones released by the pancreas. The pancreas is an organ that has many functions: it secretes a wide variety of hormones and digestive enzymes under instruction from other parts of the body.

If blood sugar is low, the brain instructs the pancreas to release the hormone glucagon into the blood. Glucagon is an “unlocking hormone” that instructs the fat cells to release fat, convert it into glucose, and push it into the bloodstream. In contrast, if the glucose level is too high, the brain instructs the pancreas to release the hormone insulin into the blood. Insulin is a ‘locking up’ hormone that instructs the fat cells to take the excess blood glucose and store it as fat. In other words, excess glucose equals excess body fat.

In a normal glucose reaction, the body carefully masters the rising level of glucose in the blood and brings it under control. There is no abnormal peak of glucose and the level never drops below the normal fasting level. In a bad reaction, we eat a food that gives us a “sugar rush.” The arrival of glucose is too rapid, and the pancreas cannot maintain this orderly processing. Instead, glucose levels spike sharply to overdose levels about 20 to 30 minutes after eating the food. This condition is known as hyperglycemia, and when this happens, nerve endings are killed off and blood vessels are damaged.

Sugar for Fat Equals Fat

Americans now worry about fat in the diet and seek out fat-free and low-fat foods. The food manufacturers have been only too happy to oblige. But almost always in such foods, they have increased the sugar content to compensate. Unfortunately, fat-free but sugary foods can be just as fattening. But the hormone insulin is then released to take the excess blood sugar and store it as fat. This insulin mechanism is the major reason why Americans are still getting fatter, even if they are trying to reduce their fat intake. Of course, when they eat fat, insulin sweeps that into the fat cells too.

This illustrates another curiosity of human biochemistry—fat by itself does not increase insulin levels. Therefore, fat eaten in the absence of either carbohydrates or protein is not easily absorbed into the fat cells. This explains how the Cretans could consume a jigger of olive oil on an empty stomach and not get fat.

The state of hyperglycemia lasts about 30 minutes, during which we do not feel anything special, and then the pancreas catches up. But it overshoots the mark—the pancreas overcompensates and clears too much glucose from the bloodstream. By 2 to 3 hours after eating the food, there is now a deficiency of glucose in the blood. This deficiency, known as hypoglycemia,
provokes feelings of drowsiness, dizziness, irritability, exhaustion, cold sweats, depression, headaches, and a desperate craving for something sugary. Many readers will be familiar with this phenomenon: the mid-morning or mid-afternoon “slump,” which happens a couple of hours after a copious bad-carbohydrate meal.

In this way, abnormally high blood sugar levels mean abnormally high insulin levels. Most Americans are putting their bodies under this kind of stress on a daily basis. This is a biochemical disaster: insulin is a powerful hormone and having it floating around in abnormal quantities (hyperinsulinemia) upsets all other kinds of hormonal reactions.

For example, insulin instructs the liver to make cholesterol. The more abnormal the insulin level, the more abnormal the cholesterol production. The reason most people have high cholesterol levels is not because they are eating it, but because their body is making abnormal quantities of it. In a similar way, abnormal insulin levels provoke abnormal levels of other hormones, which cause abnormal blood clotting (leading to strokes and thrombosis), abnormal clogging and inflammation of arteries, abnormal suppression of the immune system (allowing cancers to grow), and even increased sensitivity to arthritis, allergies, and asthma. The problem with hyperinsulinemia is that you do not even feel it. It goes about its work silently and you notice nothing until it is too late—you have the stroke, the heart attack, the cancer, and the sludged arteries.

The end result of this abuse of the blood sugar mechanism is often diabetes. Diabetes is a condition in which one of two things happens: either the pancreas cannot keep up with the demand for insulin and so the insulin production machinery goes into failure or the fat cells stop listening to insulin’s instructions and fail to absorb sugar out of the bloodstream. Either way, there is then an excess concentration of sugar in the blood. Diabetes sufferers, even if medicated, are vulnerable to heart disease, kidney failure, blindness, and gangrene in the feet and hands.

Think of abnormal insulin levels like the iceberg that sank the Titanic. You see very little on the surface, but underneath lurks danger. You just see apparently disconnected peaks—heart disease, thrombosis, artery disease, cancer, allergies, depression, arthritis, obesity—but a looming mass of ice (representing abnormal insulin levels) interconnects them under the surface.

Glycemic Index and Glycemic Load

Until the 1980s, medical knowledge about how diet affects and controls diabetes was surprisingly imperfect. Then, Canadian researcher David Jenkins developed a breakthrough concept—the glycemic index.
¹¹⁰
He fed various foods to volunteers and measured their blood sugar over a period of time, usually two hours. He then did the same with glucose. Blood sugar is, in fact, glucose and so glucose is thought to be the most “glycemic,” that is, it creates the most powerful sugar rush. Jenkins compared the spikes in blood glucose caused by the test foods against the spike for glucose, and the ratio of the two, on a scale of 0 to 100, gives the glycemic index.