(maybe off topic for some) SUGAR ADDICTION

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Sugar Addiction

Posted: 13 Nov 2009 06:02 PM PST

We all know them. Those people who eat cakes and cookies and do not gain a pound. Whereas, most of us put on the pounds quite easily. I always have seen those skinny people as the lucky ones. This may true for the modern times, but from an evolutionary standpoint, they actually have the "bad genes." During a famine, they would have been the first to go. However, the rest of us contain a better capability to store energy for future use. The problem is that our current state of gluttony seen in modern society is killing many of us - as the body was never designed for this scenario. The body is designed for energy efficiency, storage, and overall survival of the species. We are a product of our past.

In a sense it is about calorie economics. In the Paleolithic times, humans could have spent hours gathering low calorie foods (leaves and vegetables) while in the mean time burning more calories than obtainable from what was collected. This would have not made any sense for survival. On the other hand, with human intelligence, hunting allowed for shorter durations of time by stalking prey that were considered high density ( high calorie) foods like wild game.

Lets take the example of the cheetah and the gorilla. The gorilla spends most of its day consuming low density foods like leaves. It must spend a large amount of time doing this in order to obtain a sufficient amount of calories. And as such, the gorilla has a pot belly enabling digestion of the large amount of plant material. This is not the case with humans.

The cheetah, on the other hand, quietly lays in the Savannah conserving energy while waiting to catch its prey. After which there is a short burst of high intensity energy and the kill of a high density food. The cheetah, with its time and energy spent, gets "more bang for its buck" - in a loose sense.

As humans, we are omnivores consuming it all - low to high density foods. It was only recently, on the human evolutionary scale that 5000 years ago, the Polynesians were using sugar cane in their diet. This usage later spread to India, then on to the Middle East and Rome. With the discovery of the new world, this lead to the exploitation of slaves for the cultivation of sugar. Now in modern times sugar seems to play an integral of our diet - from beverages, sauces, cereals, cakes, etc. Last year I read an article talking about how sugar is addictive. I had no problem believing this - especially when I warn my patients that when going a low carbohydrate diet, there may be fatigue and withdrawal symptoms that may arise for a few days. Sugar is 50% glucose and 50% fructose. Of the two, fructose seems to be a bigger contributor to the metabolic syndrome than glucose. Excessive fructose:

 

increases uric acid levels

raises triglycerides

decreases leptin entry into the hypothalamus leading to prolonged hunger

causes weight gain

induces insulin resistance

induces hypertension (click) - refer to the recent study

Sounds pretty bad to me. Considering that Modern Americans are consuming 1/4 to 1/2 lb of sugar daily, it is no wonder that there is a rampage of obesity, diabetes heart disease, and high cholesterol in the US and the Western World. I now realize that this situation is a factor of how we are wired as humans. We are designed to ensure adequate energy consumption and conservation. A propensity to seek highly dense foods would allow for enhanced survival in the old world. But now comes in sugar and High Fructose Corn Syrup ready to establish the metabolic syndrome.

In the ancient world, the Paleolithic man/woman consumed fructose seasonally during the fruit tree blooming times. I am sure they engorged. But this was transient unlike the 1/4 -1/2 lbs of sugar today. So it appears that we are wired to follow this pattern of a higher carbohydrate consumption - but not 365 days a year . We must realize that "seasons" must change from a metabolic standpoint. It is the persistence of the "summer mode" that establishes a state of inflammation and later disease. So this bring the question - "If someone is obese, is this their fault?" The answer lays in their food choices. The wrong food, i.e. high sugar and fructose, can be addictive as we are wired to seek them. How?

A study this month reveals the brain's pathway of how sugar addiction follows the same pathway as alcohol withdrawal. The team from San Diego used rats to look at the effects of Corticotropin Releasing Hormone (CRH) on food intake. CRH is produced in the hypothalamus of the brain which later signals the pituitary gland to release Adrenocorticotropic Hormone (ACTH). ACTH later stimulates the production of cortisol (a glucocorticoid) from the adrenal glands. Some of the effects of cortisol are:

 

modulates glucose metabolism by increasing glucose production (gluconeogenesis)

lowers activity of the immune system

lowers bone formation

increases blood pressure by inhibiting the loss of sodium from the kidneys

causes a loss of collagen in the skin

In this study, rats were fed their normal food (chow) and at times supplemented with a palatable food (sugary food). They were on a food cycle of regular chow for 5 days of the week followed by 2 days of the palatable food. This cycle went on for 7 weeks. The food was freely available. After the seven weeks the rats were given a CRH receptor antagonist (receptor blocker) called R121919. The addition of R121919 reduced the consumption of the palatable food intake - the sugary food.

The researchers went on to assess whether withdrawing the sugary food elicited stress after food cycling for seven weeks. With the withdrawal of the sugary food, the rats became more anxious. However, the pre-administration of R121919 decreased these symptoms. Moreover, the withdrawal of the palatable food (without R121919) led to a five fold increase in CRH expression. But this increase in CRH returned to baseline upon reconsumption of the sugary food. These changes were seen not in the hypothalamus of the brain but rather the amygdala. The amydgala (part of the lower brain) is involved with stress and fear symptoms. The authors of the study noted that this phenomenon with CRH expression on the amygdala is congruent to the effects of alcohol withdrawal in this area.

Applying these results to humans, signifies to me that we are wired to seek high density sugary foods WHEN they are available. The concept of sugar is a new introduction to the human diet. However, glucose is seen in starchy foods like potatoes. Moreover, fructose is seen in fruits and honey. What better substance than fructose to lure an animal to keep coming back to a fruit tree. This would ensure the tree's seed dispersal. I think the concept of this study shows that humans, like other organisms, are designed to rotate with the seasons. And yet, with the over abundance of carbohydrates like grains and sugars (i.e. High Fructose Corn Syrup), we are over signalling our genes to store energy. Like everything else in life there is always too much of a good thing - especially if occurs 365 days a year. Not only did the Paleolithic man not consume grains but his diet changed with the seasons. By default, he was only seasonally on a higher carbohydrate diet.

For more information about the study,

The more we understand how our food stimulates our genes, the better we will become to cope with our present environment and over health. It is clear to me that there is much more to health than a slew of pills to be taken. Convincing others of this fact is the battle. We should look to the past to understand our present and future.

I consider this to be an important study with many more like it to come.

Here is a quote from the paper that says it all:

"Adaptively, such processes may shift food-seeking and consummatory behavior toward energy-dense, high-reward foods, while devaluing efforts to obtain less energy rich, low-reward foods (or non-foods), an adaptation evolutionarily useful when there are costs to foraging (e.g., predator exposure, limited time and energy resources). In today’s environment, however, the same processes may drive intake of foods that promote obesity at the expense of less tasty, but perhaps more nutritious alternatives."

Cottone, P, et al: CRF system recruitment mediates dark side of compulsive eating. Proc Natl Acad Sci U S A. 2009 Nov 9 (ahead of print)