jump to navigation

Survivor? Or Starvation? March 4, 2011

Posted by abueno526 in Biology, Chemistry, Nutrition.
1 comment so far

Outwit. Outplay. Outlast.

Survivor. A show with the motto above,  “Outwit, Outplay, Outlast.” Contestants are put on a deserted island with meager food, shelter, and comforts to compete in a series of challenges as they try to become the ‘Sole Survivor”.  Although the glory of winning the title is great, what is physically happening to contestants’ bodies as they put themselves under these extreme conditions?  Some, like Russell Swan from Survivor:Samoa, get fatigued earlier than others, having to be removed from the game for medical reasons.  When this shut down occurs, what is happening?  How far can they really be pushed until they move into a starvation-like mode?

How does it all start?

Typically, glucose is the major energy provider to the body.  Fats can be a precursor to glucose, and ample amounts of them in the body lead to proper function and metabolism.  When one is in starvation mode, the liver is the first to sense this.  Because the body is unable to convert fats into glucose, it biochemically makes a shift to harness more of its energy from ketone bodies in order to save the muscles from deterioration via protein breakdown.

And the downward spiral begins

This switch to the use of ketone bodies is also vital to supplying energy to the brain cells, which is a top metabolic focus for the body no matter its state. In this protection mode, and use of a new fuel source by the brain, blood glucose levels drop dramatically.  This way of living will continue until all fatty acid energy stores have been used up.  Metabolic function will switch from using ketone bodies to its last

resort of proteins for energy.  Final stages of starvation such as these can result in heart arrhythmia, liver failure , and a discontinuation of muscle functioning, ultimately leading to death.

What would you do for a million dollars?

So, when a Sole Survivor is picked at the end of 39 days, what sort of condition are they in?  Although perhaps a few sizes smaller, the contestants will not have reached a true starvation mode due to the time frame of the show and availability of some food for nourishment.  Although they can do it, it’s definitely not recommended unless you’re playing for the million dollar prize!

Mysterious Melatonin December 18, 2010

Posted by Kyle in Biology, Chemistry, Health, Medicine, Neuroscience, Nutrition, Physiology.

I am sure everyone has already heard of a little compound known as melatonin. Melatonin is a hormone that can be found in many different organisms including plants, although most people know melatonin for its actions in mammals. In humans, melatonin is produced in the brain by the pineal gland. Circulating melatonin levels have been found to be high at night and low during the day, which is consistent with research that has shown that light suppresses melatonin. Because melatonin plays a role in controlling the circadian rhythm, it has received much interest for its use as a treatment for various sleep disorders. Because melatonin is a hormone, supplementing melatonin can present some issues.

Many people have used melatonin supplements to help them sleep at night. If you take a trip to your local drug store you are likely to find melatonin on the shelf. The first time I came across melatonin supplements I couldn’t help but think about the potential negative aspects to selling melatonin over the counter, unregulated. As many of you know, the human body likes to maintain homeostasis. When this delicate balance is interrupted, the body will react to return to homeostasis. I started to wonder what happens when someone takes melatonin supplements. The first thing that comes to mind is a decrease in the amount of melatonin receptors or a decrease in the production of melatonin itself, or both. I also wondered about possible side effects of increasing melatonin levels. As we have seen with many other hormones, multiple pathways and mechanisms can be influenced by a single hormone. So someone taking melatonin to help them sleep could inadvertently throw off other pathways, like those involved in reproduction for example.

Melatonin has been shown protect against reactive oxygen species, which can wreak havoc inside cells. This could potentially be an obvious benefit to taking melatonin supplements, especially if it helps an individual sleep at night. While sifting through the literature, I was unable to find any studies specifically looking at the negative effects of taking melatonin supplements, if any. But just because it isn’t proven that something is bad, doesn’t mean the potential for bad isn’t there. Also, other countries have taken action to stop over the counter sale of melatonin. Of course, there is also the question, do melatonin supplements even work?  How much of the melatonin present in a melatonin pill is denatured by stomach acids or excreted in urine before it even has an effect?

I am skeptical of melatonin supplements, if you haven’t noticed yet. To each his own, but I don’t think I will be purchasing or taking any melatonin supplements in the near future.  Good luck to everyone on their upcoming finals. Make sure to get plenty of sleep, although if your to-do list looks like mine, that won’t be happening.

Dang My Appetite! December 8, 2010

Posted by wframe488 in Behavior, Biology, Health, Medicine, Nutrition, Physiology.
add a comment

The Biggest Loser

It wasn’t until recently America realized just how overweight people were getting in our country. I believe we are one of the most overweight countries of the world if I am not mistaken. It seems like new diet plans, weight-loss pills, and surgeries are developed everyday to help obese Americans shed those pounds. Weight-loss has definitely been growing its popularity, for example new reality television shows like The Biggest Loser , Weighing In, and Celebrity Fit Club, to name a few, have gotten people interested in getting up off the couch and exercising.

The fast food industry and video games can be partially blamed for helping Americans achieve the great honor of being one of the “biggest” countries in the world, but let’s not forget about our genetics. There are several hormones in our endocrine system that plays a role in weight regulation and weight-related behaviors like hunger and satiation. Two of the most popular and most talked about weight regulating hormones would have to be ghrelin and leptin.  We all typically produce these hormones, but in different amounts depending on the person. Ghrelin is a preprohormone that is normally produced in the stomach. It is a known appetite inducer and has also been known to slow down metabolism and decrease the body’s ability to burn fat. It stimulates the hypothalamus to release growth hormone via a GSH receptor. Leptin, on the other hand, is known to aid in appetite inhibition. It is expressed predominantly by adipocytes and contains highly expressed receptors in the hypothalamus region of the brain. It stimulates the hypothalamus via an Ob receptor to decrease appetite and body weight.

Ghrelin and Leptin Action Summary

One research article that I found about this particular topic, by J.P.H. Wilding, was titled “Food Fails to Suppress Ghrelin Levels in Obese Humans”. This research paper investigated the effects of a test meal on the plasma levels of both ghrelin and leptin. They sampled 13 lean and 10 obese subjects and found that the lean subjects exhibited a decrease in both ghrelin and leptin levels after a meal whereas the obese did not show any signs of decrease in concentration of these two hormones. The paper goes on to explain that the role of the decline in leptin of the lean subjects is unknown, but the lack of suppression following a meal of the obese subjects could lead to increased food consumption. This suggests that ghrelin is involved in the pathophysiology of obesity. This appetite inducing hormone is secreted by our bodies with out our control unfortunately and for those that secrete more will mostly likely tend to be bigger human beings just based off of overall caloric intake.

Food Groups

In regards to dieting, one major problem that almost all people possess after they diet is the regain of weight. This mainly is due to the idea that even though your weight is now maintained at a healthy level your appetite still remains the same as it once was, thanks to these two hormones mentioned previously. One interesting article that I read from the Journal of Clinical Endocrinology and Metabolism, was titled, “Appetite Hormones May Predict Weight Regain After Dieting”, which was by Ana B. Crujeiras. Her colleagues and her evaluated a group of 104 overweight men and women during an 8-week low-calorie diet and again 32 weeks after treatment. The scientists measured body weight and plasma ghrelin and leptin levels before, during, and after dieting. What is interesting about this article is that the researchers found that subjects with higher plasma leptin and lower ghrelin levels before dieting were the subjects that were more prone to regaining weight after they shed those pounds through dieting. Personally, I thought that the higher the ghrelin levels prior to dieting would cause the subject to be more prone to weight regain, but that’s not the case here, but that’s science. The article goes on to explain that this can be useful information and that these hormone levels can be proposed as biomarkers for predicting obesity-treatment outcomes.

In conclusion we know that virtually everyone produces ghrelin and leptin in there bodies and that these two hormones play a big role in regulating our appetite. Some of us are lucky enough to sustain the proper balance of these hormones, based solely on our genetics, for body weight maintenance. Although, others aren’t so lucky to possess such a talent. Just because someone is lean and skinny doesn’t mean that they are necessarily healthy, and just because someone totes around more body weight than others doesn’t mean that that person is necessarily unhealthy. In closing, all I have to say is that eating right and exercising is a big part of being healthy and maintaining weight despite what these pesky hormones are doing to our appetite. So, to everyone, eat healthy and exercise!

The Science of Satiation October 16, 2010

Posted by Kyle in Behavior, Biology, Chemistry, Health, Nutrition, Uncategorized.

Slow down or you’ll get a stomach ache!

My parents always told me that if I eat my food really fast, I may feel sick later. I am sure most people have experienced this at least once in their life. It seems that the reason for this is…that the faster you eat, the faster your stomach fills up. Your stomach ends up being full, or over-filled, before your body realizes it. By the time you do feel full, it is too late to stop eating and your stomach may feel like it’s going to explode.

It’s bad enough that your favorite meal can cause you pain after you devour it, but that’s not all it will do. Common sense should tell you that eating too much of something can potentially lead to being overweight. So if you’re eating too fast you can end up doing just that, gaining a lot of weight. An article from the British Medical Journal points out that eating too fast triples the risk of being overweight. Makes perfect sense…more food in equals more pounds put on.  But  the next question remains: what are the mechanisms behind all of this?

The science of satiation

An article out of The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM) points out that gut hormones my play a part in why people who eat fast end up overeating. As Alexander Kokkinos, MD, PhD, of Laiko General Hospital in Athens, Greece points out, gut hormones that signal the brain to stop eating may be impacted by the rate of eating.  The hormones that Kokkinos article examined were peptide YY (PYY) and glucagon-like peptide (GLP-1) which work to signal to us that we are full after a meal. For the study, the researchers took blood samples from participants after they had all eaten the same meal, however, the amount of time each participant took to eat the meal varied.  Their results showed that the participants who took longer periods of time to eat the meal had higher levels of the gut hormones and felt more full than those who ate their meals faster. So what does this all mean?

Fast food

Your body tries its best to tell you stop eating, but if you don’t get the signal in time it doesn’t matter.  As many Americans go about their day, they consume a massive amount of calories for very little cost. Going through the drive through doesn’t burn nearly as many calories as chasing down a woolly mammoth. Our early ancestors couldn’t go through the drive through for dinner, they had to work for their meal. Not only that, they probably didn’t eat nearly as much as we do today.  Consuming a ton of calories and burning very few  makes someone more likely to be overweight, but if you add in the fact that some people are consuming their meals in only a few minutes and eating large portions, these people are at a much higher risk of gaining weight. So next time you sit down for a meal, try and eat slowly. This will give your gut time to tell your brain that it’s time to quit eating.  Your gut will be happy, and you may just lose a few pounds in the long run.

Will fruits and vegetables really prevent disease? April 28, 2010

Posted by zach in Genetics, Health, Medicine, Nutrition.
add a comment

Has you mother ever told you,” You are what you eat?”

With new discoveries being made daily, there is emerging research showing the interaction between environmental and dietary influences in the development of diseases such as cancer.

A new study published in the  Journal of the National Cancer Institute shows there is a weak relationship between high fruit and vegetable intake and your overall cancer risk.  During the 1990’s it was widely thought that fruits and vegetables could prevent cancer and other diseases.  To date there is a lack of studies that could conclusively prove the claim about fruits and vegetables preventing cancer on a large-scale.  But just because they can’t prove it on a large-scale isn’t to say that you should stop eating your fruits and vegetables and go on an all fast food diet.

On a smaller scale it has been found that a substance found in vegetables can combat cancer epigenetically.

Epigenetics is the study of how gene expression can be altered without changing the underlying DNA sequence, this can be done with methyl and acetyl groups. Enzymes have been found that can effect how the chromatin is condensed. When the chromatin is in an extremely condensed state transcription is limited because the polymerases struggle to attach to the DNA template.

Histones acetyltransferaes (HATs) and histone deacetylases (HDACs) are used to add and remove an acetyl groups, these acetyl groups regulate the biochemical structure of the DNA that regulates gene expression. Three key dietary components that have been shown to affect HDAC and HAT activity  1) butyrate, which is formed by fermentation of dietary fiber in the colon, 2) diallyl disulfide is found in garlic and allium (onion family) vegetables, and 3) sulforaphane, which is found in coniferous vegetables.  All three of these substances have been shown to prevent cancer in clinical and preclinical trails by inhibiting HDAC enzymes.  Even though fruits and vegetable have yet been linked to preventing cancer on a large-scale, certain substances found in vegetables have been found to prevent cancer. Maybe it is not enough just to eat the fruits and vegetables, researchers may have to isolate these cancer fighting compounds in order to use all of natures cancer fighting power.  Even though a strong positive correlation between cancer and fruits and vegetables is yet to be found, you may want to continue to eat healthy.  From researching how diet can affect epigenetics there is a clear relationship between cancer, epigenetics, fruits, and vegetables.  Researchers are just going to have to continue to look for ways to harness some of the anticancer properties of both fruits and vegetables.

Figure 1

Stop drinking Gatorade and try a bowl of cereal! April 27, 2010

Posted by Jill in Biology, Chemistry, Exercise, Health, Medicine, Nutrition.
1 comment so far

Following a long workout, most athletes prefer to drink massive amounts of water or a sports drink such as Gatorade or Powerade to refuel and quench their thirst. The benefit of sports drinks has long been discussed because they restore electrolytes and carbohydrates and aid in recovery following strenuous burning of calories. Water is an important player in rehydration, but most athletes know that post-workout they need to drink a sports drink to help them get through the next few days to prevent muscle fatigue and to able to continue to compete as early as the next day with as little muscle pain has possible.

Gatorade.. the drink of champions?

The carbohydrate-based sports drinks, like Gatorade and Powerade are usually used to replenish and refuel after competition-based sports or following a long run. The electrolytes in sports drinks aid in preventing lactic acid build-up in the muscles, preventing cramping following strenuous exercise.  An exercise physiologist from the University of Texas at Austin, Lynne Kammer, researched the physiological effects of certain types of foods. In this research, Kammer and her students studied 12 cyclists (8 male, 4 female) in order to determine the effects of whole grain cereal and milk versus sports drinks. Based off of protein synthesis and glycogen replenishment, whole grain cereal and milk performed as well as, and in cases, better than the sports drinks.

Cereal... the real food of champions

Cereal and fat free milk are a cost effective option over pricey sports drinks and potentially provide the same nutritional value. Although relatively inexpensive, as an athlete, cereal and milk do not sound as appetizing as a bottle of Gatorade following a hard workout.

The full contents of this study can be found in Journal of the International Society of Sports Nutrition

The Full Story Behind Antioxidants February 12, 2010

Posted by zach in Biology, Chemistry, Exercise, Health, Nutrition, Physiology.
add a comment

A recent article out of Kansas State University by Steven Copp shows that antioxidants may not be everything the media has hyped them up to be in being able to increase muscle performance.  Their data shows that in certain cases when people supplement antioxidants they can actually impair muscle function. While antioxidants at certain dosages may be considered an ergogenic aid, there has been a large amount of media hype which has attributed to their recent growth.

Copp found that antioxidants can have an effect on the blood flow in the muscles.  This is possible by antioxidants decreasing the concentration of oxidants in our body.  This all sounds good, but hydrogen peroxide which is naturally occurring pro-oxidant in our body is a vasodilator. In short when you supplement large quantities of antioxidants you are drastically decreasing oxidant concentration in your body, this in turn can cause your veins to constrict from a lack of vasodilators, which limits the amount of oxygen to your muscles.  This effect can lead to changes in key signaling mechanisms that can also have adverse effects on functioning muscles.

With all this being said it’s not that you should stop eating antioxidant rich foods.   Researchers are still looking at the full physiological effect of antioxidants on exercise training.  What the researchers are saying is you have to consider your antioxidant pro-oxidant balance.  Next time you are at the store and see antioxidant supplements claiming to have extraordinary effects, you may want to look at the science behind what you are buying before you buy a supplement that has a null effect on your muscle performance.

Full article on Science Daily

Antioxidants at work