Saturday, July 23, 2011

Do We Feel What We Eat?

I would like to interrupt my programmed writing schedule for an additional entry on diet and how it affects us. A friend of a friend told me that there was a discussion on how food affects our mood and may help us cope with what we may feel. Before you believe these claims, I’ve written something down to get you to a thinking mood.

Let’s start things off with something easy, the easiest being the “sugar rush.” Although most parents attribute their children’s manic behaviour following a large intake in sweets to the intake itself, it would be nothing short of folly to attribute this as the sole explanation. The best instances to consider are those where sugar, either alone or with substances considered neutral with regards to affecting our mood, are administered in a controlled environment. One of the things that may come to mind is intravenous dextrose. To be honest, I’ve never seen a patient happy while an intravenous line was attached, regardless of how much sugar we pumped into their veins. However, one could rationalize that either the amount was not sufficient or perhaps ingestion was a necessary component. Giving a 50% glucose solution via an intravenous push does not give a rise in excitement either, perhaps due to the fact that administration of a viscous solution into a blood vessel is a painful experience.

The oral glucose tolerance test (OGTT) involves the ingestion of 75 g of glucose dissolved in a glass of water. There are several people who complain that this test is extremely nauseating; indicating that it often pushes against our limits of ingesting sugar. For those who do not complain, there is no excitement or happiness. The predominant mood being an anxious one, chiefly due to thoughts on whether they have diabetes, pre-diabetes, or not.

So maybe it isn’t glucose. Table sugar is sucrose. It is made mainly of two sugar molecules, mainly glucose and fructose. Fructose is the sugar commonly found in fruits. I don’t see children get the sugar rush, regardless of how many ripe mangoes and mango shakes they consume. To cut a long story short, there may be a period of hyperactivity in people after they consume large amounts of sugar. However, more frequent reliable observations show that this may be due to something else in the situation rather than just sugar. Perhaps the fulfilment of a guilty pleasure is enough?

Another thing that bugs me is the frequent assumption that an increased intake of tryptophan-rich food will result in an increase in the serotonin levels of the brain. Considering that the human body is fully dependent on outside sources for this amino acid, the statement may seem plausible. This also means that it is available in very low concentrations within our body. There are two ways that this molecule may be fashioned three-dimensionally and they are called the D- and L- forms. Our body uses the L- form and it is called L-tryptophan.

The biggest investment of our absorbed tryptophan is, of course, protein synthesis. This only concerns structural proteins and proteins that speed up chemical reactions (called enzymes). Now before the tryptophan goes to serotonin, it also goes to a pathway responsible for vitamin B level maintenance. According to present day estimates, only about 3% of dietary tryptophan is used in the manufacture of serotonin. The funny thing is that, in mammals, 80-95% of our serotonin is found in our stomach. So isn’t it more plausible to believe that it would more likely be able to affect gastrointestinal function than brain activity?

The absorption and metabolism of tryptophan is an extremely complicated and boring discussion. Suffice it to say, given their levels all throughout the body; it should affect a lot more than just our mood. But it doesn’t.

One common flaw in reasoning is the assumption that, when two things happen together frequently, it's a cause-and-effect relationship. It just means that there is an association. Proving one causes the other is another thing altogether. Common sense screens the obvious associations that do not cause the other, like people having the same birthday or the rooster crowing in the morning.

Remember that people don't eat pasta because they're lonely. It’s just as believable as kids eating spaghetti because they’re lonely.

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