The Importance of Temperature In Health

Humans are not ectotherms like lizards. Humans are endotherms and we need to regulate our body temperature from the inside. Our physiological homeostasis, meaning our well-being and optimal function, depends on a stable core temperature. Several organs are involved in this process. The sympathetic nervous system communicates to the hypothalamus by shivering or sweating to signal that the external temperature is changing, so the inside temperature has to adapt. The hypothalamus then tells the thyroid to respond to the temperature outside our body by raising or lowering thyroid hormone levels and increasing or decreasing thermogenesis. This complex system can fail if the thyroid cannot respond by producing or maintaining adequate hormone levels.Some people don't sweat, while others are very sensitive to increased temperature and sweat profusely. Some people can get sick without ever getting a fever, which means their immune defense system is dysfunctional. If this happens, the adrenal glands that activate the sympathetic nervous system through neurotransmitter signaling will be unable to properly signal the thyroid, breaking the thermostat.

People who suffer from adrenal issues will often have a hard time regulating temperature, feel horrible in the heat, and love the winter. People with thyroid issues will love hot weather but endure frozen hands and feet in the winter, bundling up in several layers more than their friends. Still, there are plenty of in-between people as well. These are two extremes. There are innumerable variations to this imbalanced thermoregulatory system. How you feel and adapt to a particular temperature is a sign of what is going on under your skin, deeper inside, where your core temperature is crucial to maintaining an unquantifiable quantity of biochemistry. Your temperature regulation is an easily identifiable symptom.

Biochemical reactions are made possible by enzyme activity. Enzymes only work at a certain temperature. We are mostly told to worry when our body is too hot. When our immune system, through the adrenals, ratchets up our core temperature. The adrenals raise body temperature so a fever can destroy a virus (viral proteins unravel at lower temperatures than bacteria) and trigger cytokines to mount an inflammatory response to kill bacteria with heat shock proteins, making bacteria unravel. Recent studies have shown that a natural fever is more effective at reducing infection and not as dangerous, as previously thought. A fever's beneficial effects in response to infection can be safer than lowering it with antipyretic drugs like acetaminophen, ibuprofen, and aspirin.

Not much is said about when the body is cold. I don't mean hypothermia, which is defined as below 35 C and 95 F. Maybe you fell into a freezing lake or got stuck on a mountain pass in the snow. This cold surpasses the thyroid and adrenal glands' ability to warm you to a homeostatic level. That is an extreme and dangerous situation. I'm referring to a milder low temperature. One that doesn't give you goosebumps and makes you reach for your sweater, a temperature under 37 C or 98.6 F. When your core body temperature has a hard time getting to or near 37 C or 98.6 F, a lot of biochemistry won't get done or won't get done well because many enzymes, the proteins responsible for all biochemical reactions in our body, won't be formed properly if your body is below that optimum temperature.

Enzymes function when they take a certain shape. Their shape is what makes them speed up and catalyze chemical reactions. They vibrate and jiggle to attach themselves to active cellular substrates. Each enzyme has a particular three-dimensional shape to create a lock and key action that catalyzes a chemical reaction. Core body temperature has to be optimal for enzymes to be active, to have the right shape, and to vibrate and jiggle in the right way. Too hot, they get hard, like cooked egg white; too cold, they don't take any shape at all. Enzymes exist only to catalyze reactions. They make everything happen in the body. You already know about digestive enzymes. The pancreas secretes trypsin to break proteins into amino acids, or proteins that would just sit in the intestines and never be metabolized. Pepsin, in the stomach, turns proteins into peptides; otherwise, the protein there would remain unmetabolized. Is food not getting digested? Sure you can take digestive enzymes, but why can't you make your own enzymes? Is it because the temperature in there is too low?

But it's not just about metabolizing food. There are so many other crucial enzymatic functions. Aromatase is found in many tissues and converts testosterone to estrogen. Cytochrome P450 converts cholesterol into pregnenolone. A deficiency affects the formation of sexual characteristics, fertility, and the immune system. Any metabolism, both catabolic and anabolic, depends on enzymes. 37 C and 98.6 F is supposed to be the magic number at which all enzymes in the human body function optimally. That is a number that people usually reach mid-day when they are up and about. In the morning their temperature might be a bit lower. At night it will drop about 2 degrees from 37 to 36 C or 98.6 to 96.6 F so you can sleep, as cortisol drops during the night and melatonin rises. Because cortisol is lower, your sympathetic nervous system dials down as it goes into sleep mode. In the morning, your core body temperature should increase again because thyroid and cortisol hormone levels are at their highest. That's when you're supposed to wake up, ready for the day!

Many people's core body temperature does not rise high enough to allow some enzymatic reactions. An important test is your waking temperature before the sympathetic nervous system stimulates you. This can reveal how well the thyroid and the adrenals can bring your body's energy to its circadian peak.

There are untold different kinds of enzymes. Some are more thermally sensitive than others. Some enzymes will withstand a slightly lower-than-optimal temperature and still be able to catalyze the biochemical reactions that make us function. But your heart will have trouble beating, and your brain will start to malfunction at 35 C or 95 F. These two organs are imperative to keeping you alive. They will keep functioning, not optimally, but operate at temperatures from 35.4 to 36.2 C and 95.9 to 98 F. Stil, countless other enzymes are more sensitive to lower body temperatures, and these are usually organs that are less crucial to immediate survival. Few pepsin enzymes are in the person's stomach with a lower-than-optimal temperature. That will affect their digestion and nutrition, but it won't kill them. Without adequate body temperature, fewer aromatase enzymes catalyze in bone, breast, and brain tissues that require steroid hormone conversion from testosterone to estrogens. They won't die, but they might have menopausal symptoms. Not because they don't have ovarian estrogen but because the testosterone that started as a cholesterol molecule did not convert along the way.

Without enough of the enzyme Cytochrome P450, less cortisol, and less vitamin D will be catalyzed. The ovaries and testes will have fewer aromatase enzymes to catalyze the steroid conversion in their active sites. Physiological functions such as skin, hair, nail regeneration, cognitive function, mineral regulation, and all the biochemical reactions that enzymes need to activate can be suspended or simply slowed down if your temperature is not optimum. If you have health issues that don't have an obvious cause, I recommend checking your core body temperature. It's easy enough to do with a glass thermometer. A digital thermometer only measures local skin temperature if you have a fever. It cannot measure core temperature. Your low temperature may be the root cause you've been looking for.