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True or False – Men have a higher tolerance for alcohol than women?

Posted on May 21, 2013

True.

This myth is very interesting. I asked a number of my friends if they thought men had a higher tolerance for alcohol, all said no. They felt confident that men and women metabolize or oxidize alcohol the same way, at the same rate, etc. In actuality, men and women are different in regards to how their bodies respond to alcohol. First, men on average are a little bigger and have more body mass than women. This additional body mass may allow a greater distribution of alcohol throughout the body in men, which would then result in a slightly lower blood alcohol content. In addition to being bigger than women, men also have a greater percentage of muscle mass which means the water content of their bodies is higher.

Men’s bodies are usually 55% to 65% water compared to 45% to 55% for women. Since men have a greater percentage of muscle mass, women usually have a higher percentage of body fat compared to men. Alcohol doesn’t dissolve in body fat, but it does in water. This also allows for a greater distribution of alcohol throughout a man’s body and would result in slightly lowered alcohol content in the blood. Possibly the most significant difference in how men and women metabolize alcohol has to do with an enzyme called alcohol dehydrogenase (ADH). This enzyme actually starts to metabolize or break down alcohol in the stomach. More alcohol leaving the stomach will ultimately result in a higher blood alcohol content. Seitz et. al. (1993) conducted a study looking at ADH activity in men and women and concluded that “women exhibit a significant lower gastric alcohol dehydrogenase activity than men when alcohol dehydrogenase is measured at high ethanol (alcohol) concentrations.”

Resource:
Seitz H, Egerer G, Simanowski U, Waldherr R, Eckey R, Agarwal D, Goedde H, Von Wartburg J: Human gastric alcohol dehydrogenase activity: effect of age, sex, and alcoholism. Gut (1993), Vol 34, pps. 1433-1437.

Categories: Myths

True or False – Cracking your knuckles leads to arthritis?

Posted on May 15, 2013

False.

Some children start cracking their knuckles because they like the cool sound it makes, some because they say it feels good, and others do it just because they know it annoys their parents. So what causes the “crack” or “pop” anyway? In basic terms, it’s caused by air or gas bubbles being released in a joint. A more detailed explanation is offered by Castellanos & Axelrod (1990). They write “Cracking of the knuckles results in a rapid increase of intrasynovial tension. This increased tension results in synovial fluid cavitation, which causes rapid separation of the joint and collapse of the vapour phase of the formed cavity. The consequent release of vibratory energy provides the cracking noise.” No matter what causes the sound, parents have long been warning kids against knuckle cracking for fear it will lead to arthritis in old age. Only a few studies have examined whether habitual knuckle cracking leaves the “crackers” disfigured and suffering from painful arthritis in old age. The results of these studies suggest that there is no relationship or association between cracking knuckles and arthritis. It seems reasonable to think that cracking your knuckles would lead to damage of the cartilage that covers the ends of the bones in your fingers and hands (think of the awful sound cracking your knuckles makes), but it is not true. The above mentioned authors conducted a study in which they compared knuckle crackers vs. non-crackers and found the crackers didn’t have increased rates of arthritis in old age. They did find however, that those who did habitually crack their knuckles were more likely to have hand swelling and decreased grip strength and they suggest that habitual knuckle cracking should be avoided.

Reference:
Castellanos J & Axelrod D: Effect of habitual knuckle cracking on hand function. Annals of the Rheumatic Diseases (1990), Vol. 49, pps. 308-309.

Categories: Myths

True or False – Having a slow metabolism is a major cause of obesity?

Posted on May 7, 2013

False.

As an individual who has worked in the area of health and wellness for many years, I’ve frequently heard people grumble about how thin people can eat lots of food and not gain weight, and how others (usually themselves) simply need to look at something like a piece of chocolate cake and they start to gain weight and inches. Many times overweight or obese individuals blame their weight status on their “slow metabolism”. However, research doesn’t support the idea that being overweight or obese is the result of a slow metabolism. Dr. Donald Hensrud on MayoClinic.com states, “Yes, there is such a thing as a slow metabolism. But it’s rare and it’s usually not what’s behind being overweight or obese – that’s usually a matter of diet and exercise.” In addition, Dr. Hensrud says things like genetics, family history, certain medications, lack of sleep, and unhealthy habits like skipping breakfast are more likely contributors to weight gain. Your metabolism (sometimes referred to as resting metabolic rate or basal metabolic rate) refers to the number of calories you burn just to keep your body working or functioning properly. Bodily functions such as your heart beating, breathing, digestion, and muscle contractions all require energy (calories). Research has also shown that overweight or obese individuals usually have a higher absolute metabolic rate as compared to thin or lean individuals, simply because heavier individuals have a greater amount of body mass. When body size is taken into account, metabolic rates of obese and non-obese individuals is usually very similar. In an article entitled Energy metabolism and obesity published in the Medical Clinics of North America, Dr. Michael Goran states “Some longitudinal studies support the idea that reduced energy expenditure is a risk factor for the development of obesity, but most do not.”

Reference:
Goran M: Energy metabolism and obesity. Medical Clinics of North America (2000), Vol. 84, pps. 347-362.

Categories: Myths

True or False – A cut will heal faster if you keep it covered at night?

Posted on May 1, 2013

True.

I have the opportunity to travel a fair amount and give many talks and presentations on health myths and misconceptions. I routinely ask participants in those talks if they think it is best to uncover a wound and let it air out at certain times (e.g., when going to bed). I would say that 95% of those I ask think it is a good practice to uncover wounds and let them dry out as they think this promotes healing. It’s no surprise so many people have this misconception, as mothers and fathers have been telling their children this for years. Before researching this topic, I actually told my children the same thing. Keeping a wound covered will keep the area moist and promote new tissue (cell) growth. Not covering a wound, and having it dry out, usually results in increased scab formation, which can lead to increased scarring. Scabs also slow the rate of healing as healthy regenerative tissue has a more difficult time covering a wound if it is scabbed over. Keeping a wound covered also decreases the risk of infection as a covering will help keep dirt and bacteria out of the wound. Finally, a covering will help reduce the risk of re-injury. Most of us have had the unpleasant experience of having a scab break open or tear off or have a wound re-open because it gets bumped or scrapped up against something, a covering can help prevent this from happening. Well designed research studies have shown that covering a wound usually increases healing rates by 3 to 4 days. Dr. Joel Beam (2008) did a study where he created abrasions with sandpaper on research participants (doesn’t that sound like fun). Dr. Beam covered some wounds but also left some uncovered and concluded that covering wounds significantly increases healing rates. So, tell your children to keep those wounds covered, even when they go to bed!

Reference:
Beam J: Occlusive dressings and the healing of standardized abrasions. Journal of Athletic Training (2008), Vol. 43, pps. 600-607.

Categories: Myths