I am just coming down from that finals rush that us university students are all so accustomed to. Those long nights of studying and early mornings to keep studying – it gets tiring. A lot of students have a particular molecule to thank for getting them through those long days: caffeine. Whether it’s coffee, or energy drinks, students can be seen anywhere on campus chugging down these caffeinated substances. But how does this particular substance work to keep the students active and awake?

What is Caffeine?

Caffeine is a purine alkaloid, which is a particular type of chemical compound. It is found organically in Coffea arabica and Camellia sinsensis.

Coffea arabicaCamellia sinsensis

Coffea arabica is the source of coffee, while Camellia sinsensis is the source of tea.

How does caffeine affect our systems?

Caffeine can be completely absorbed by the stomach and small intestine within 45 minutes, and it takes around 3 to 4 hours just to remove half of the consumed caffeine from your system.

Caffeine stimulates our central nervous system (CNS), which is composed of our brain and spinal cord. By stimulating the CNS, the caffeine molecules fight against drowsiness and helps keep you alert. It does all of this by preventing a nucleoside, named adenosine (which is found in our DNA!), from binding to its receptors in the brain.

Adenosine usually suppresses the CNS when it binds to its receptors; this leads to general drowsiness. When caffeine binds these receptors, adenosine can no longer interact with the brain receptors which leads to a decrease in drowsiness (or increase in alertness!). Another result of caffeine binding these receptors is the stimulation of other neurotransmitters that also lead to an increase in your ability to concentrate and stay awake. These neurotransmitters include: norepinephrine, dopamine, acetylcholine and serotonin (which will be explored later).

An interesting fact about caffeine is that its half life,which is the time it takes to remove half of the consumed substance from your system, can be shortened by one’s smoking. So if you’re smoking, you’re going to need more caffeine than the average person to get relatively the same jolt of energy.

And that’s a brief summary of caffeine and its effects! Now you know how exactly caffeine works to become your savior through those long nights. Thanks caffeine, on behalf of all of us sleep-deprived students.

Lactose Intolerance and Diarrhea

I know, I know. Oy with the poo already! But I swear, this is the last one (for now). Since I’ve talked about diarrhea due to gastrointestinal infections, I should probably explain why some people get diarrhea as a symptom to lactose intolerance.

Difference between diarrhea caused by GI infections and Lactose Intolerance

Last week, we learned that our bodies don’t absorb the water we ingest when there is a GI infection, which means we don’t gain any water in our systems. In contrast to diarrhea as a result of an infection, water is actually taken from the body and enters the intestinal tract; that means we actually lose water we already had. But why?

Diarrhea as a symptom of Lactose Intolerance

When you have lactose intolerance, you have a decreased efficiency in the digestion of lactose. While there are bacteria in your intestinal tract that are capable of digesting the lactose, they may not be able to digest all of the lactose you’ve consumed. This means that there is a concentration of lactose in your intestines that has not been taken up by your body. This is where the water loss comes in.

Remember that pesky biology lesson about Osmosis? Well, it’s actually applicable here (thank you, high school!). So, you have a high concentration of sugar (lactose) in your intestines and a lower concentration in the external environment of the intestine. Water likes to do this thing where it moves from areas of low concentrations of solutes, like sugars, to higher concentrations of solutes. Basically, water is a gold-digger and the more solutes an area has, the richer it is. So the water flows into your intestinal tract until the concentration of the sugars in your intestine is roughly the same as the concentration of the sugars outside of the intestine (this is called an equilibrium). This increased volume of water in your intestines causes a watery stool (aka diarrhea!).

Always remember that it’s important to stay hydrated anytime you have diarrhea.

Lesson here is: don’t ingest crazy amounts of lactose, especially if you’re lactose intolerant… unless you’re taking lactase pills. If you’re taking lactase pills, you can eat all the poutine that your heart allows! (That reminds me, happy belated Canada day!)

Lactose Intolerance

So, one of my friends and I have recently discovered that we’re probably lactose intolerant after eating some sweet, delicious, pain-inducing ice cream. So I thought I’d talk a bit about it and explore how one can develop lactose intolerance.

What is Lactose Intolerance?

This is when an individual is unable to digest a particular sugar, lactose, that is found in dairy products. Lactose is a molecule that is made up of two smaller sugars: glucose and galactose. Your body prefers sugars in their simplest forms so that you can easily obtain energy from them.

To get sugars in their simplest forms, you require different enzymes (which are little protein superheros) that break the sugars. For lactose, you need a specific enzyme known as lactase to simplify it into glucose and galactose.

People who have lactose intolerance do not have much of this enzyme, resulting in their difficulty in digesting lactose.

So what happens to the lactose that they don’t break down? This lactose gets broken down by bacteria. Byproducts of this bacterial reaction are methane and hydrogen gases. The digestion of lactose via bacteria causes the symptoms of lactose intolerance: gassy-ness (due to the methane gas), bloating, cramps and diarrhea (sounds like the beginning of a Pepto Bismol commercial, I know).

Make sure you don’t confuse lactose intolerance with an allergy to milk. An allergy is different than the inability to digest something!

How can someone develop lactose intolerance?

Some researchers have found that we develop less enzyme levels as we grow older, including lactase levels. This is likely why I’m more sensitive to dairy now than I was when I was a youngin’ (when I used to eat blocks of cheese and drink cartons of milk). TMI maybe? Okay, sorry.

There are individuals who are lactose intolerant at a young age, which may be due to genetics, damage to the cells that produce lactase, or a premature birth of 6 weeks or greater. The latter reasoning is only a temporary state, however.

How common is lactose intolerance?

Lactose intolerance is actually viewed as a regularly occurring health issue and, therefore, normal. There are supplements available to those who require help digesting lactose, including lactase pills and drops that you take before eating dairy foods or put into your dairy drinks.

So don’t fret, my lactase-deficient friends! We’ve been saved. And now we can eat our ice cream with smiles all around.

Cholesterol – Bad?

Last week, we talked about the good side of cholesterol, which we don’t really hear about. No, instead we hear about the evils of cholesterol and how it can lead to heart disease. But cholesterol seems to help us out a lot, so what makes it so bad?

Types of Cholesterol

There are two ‘types’ of cholesterol. I use ‘types’ but it’s really the type of transport that the cholesterol uses that differentiates one ‘type’ from the other.

You see, cholesterol requires a transport system between the liver, where it is predominantly produced, and other cells because cholesterol is insoluble. The transporters for cholesterol are lipoproteins. Lipoproteins are molecules that consist of a mix of lipids and proteins. The lipid portion of the lipoprotein can interact with the cholesterol, while the protein portion allows the complex to travel in the bloodstream.

There are two different transporters that transport cholesterol; LDL and HDL. LDL stands for Low-Density Lipoprotein while HDL stands for High-Density Lipoprotein. LDLs transport cholesterol from the liver to the other cells in the body, while HDLs transport cholesterol from the cells of the body to the liver.

“Bad Cholesterol”

This refers to cholesterol that is being transported by LDLs. Since the LDLs carry the cholesterol from the liver to the cells, which have a lower storage capacity for cholesterol, there is the possibility of the build-up of the LDLs (and cholesterol) in your bloodstream if you have more cholesterol in your bloodstream than is required for your cells. The build-up will occur on the walls of the arteries that lead to your heart and brain. Too much build-up can result in the formation of a clot, which can induce heart attacks or strokes.

They’re not all bad…

HDL is the superhero of lipoproteins. It’s like the older sibling that looks out for their younger sibling, slowly cleaning up any mess they make. HDLs carry cholesterol from the cells and the bloodstream back to the liver, where it can be broken down into bile and then stored in the gallbladder. On their way, they can help clean up the LDLs’ messes by grabbing them and dragging them back to the liver, where the cholesterol is deposited for further storage. This reduces the amount of LDL in the bloodstream, reducing the build-up in your blood and reducing your risk of heart disease. This is probably why HDLs are referred to as “Good cholesterol”.

LDLs are larger than HDLs, which is probably why the former causes clots whereas the latter doesn’t.

Lowering your Risk

You produce LDLs and HDLs naturally. While you can’t control exactly how much your body produces, you can control what you eat as it was found that certain fats stimulate the production of LDLs.

The American Heart Association’s Nutrition Committee strongly advises these guidelines for people over the age of two:

  • Limit total fat intake to less than 25–35 percent of your total daily calories (TDC)
  • Limit saturated fat intake to less than 7 percent of TDC
  • Limit trans fat intake to less than 1 percent of TDC
  • The remaining fat (17-27% of TDC) should come from sources of monounsaturated and polyunsaturated fats
  • Limit cholesterol intake to less than 300 mg per day, for most people.  If you have coronary heart disease or your LDL cholesterol level is 100 mg/dL or greater, limit your cholesterol intake to less than 200 milligrams a day.

Your physician can check your cholesterol levels by performing a blood test. You want to keep your LDL levels below 130mg/dL and your HDL levels ideally above 60mg/dL. You want low LDL levels and high HDL levels to reduce your risk of heart disease. If you have high LDL levels (the dreaded “high cholesterol”) and/or low HDL levels (the dreaded “low cholesterol”), then you’re going to want to look into dietary and lifestyle changes.

So, it looks like cholesterol can be the good guy or an accomplice depending on who it’s traveling with. Or, I suppose it could be considered a bystander. But now you know that bad cholesterol doesn’t really have to do with the cholesterol itself, but rather its ride.


American Heart Association. 2013. Know Your Fats. <> May 30, 2013.

Cholesterol – Good!

Since we talked about a type of diet last week, I thought it would be ideal to talk about another thing that is often brought up in regards to our diet: cholesterol. We hear about cholesterol, having high or low levels of it, and something about all of that being bad but what is cholesterol? Why do we even have it?

What is Cholesterol?

Cholesterol is a type of organic steroid that is mostly produced in the liver, but is also produced in all of your other cells. That’s right, you make cholesterol. So, it looks like diet is not the only contributor to cholesterol levels.

But why would our bodies produce cholesterol when it’s apparently so awful?

Cholesterol and our Body

Cholesterol is a very helpful molecule, even though it’s received some bad street cred for causing heart disease among other ailments. The membranes of our cells, which will be explored in more detail at some point, require a certain amount of fluidity in order to control what can enter our cells and what doesn’t. There are times, such as in high temperatures, when our cell membranes are too fluid. This will lead to our cells letting  more molecules in than it should be, and can lead to our cells spilling its contents out since it’s lost its relatively stable membrane. Cholesterol helps to restrict the membrane’s fluidity by incorporating itself into the membrane. This allows the membrane to be stronger and prevent strange particles from entering our cells without the proper identification.

Cholesterol also acts as the precursor, or the beginning molecule, for the synthesis of other important molecules in our body. Some of these molecules include steroid hormones, like estrogen or mineralocorticoids (like aldosterone), as well as bile acids, which help to emulsify fats in the small intestine.

So that explains why we make cholesterol, and, so far, it seems wonderful! It’s involved in the production of some hormones, helps emulsify fats and prevents our cells from turning to jelly.

Why should we be wary of cholesterol though?  What role does our diet play in this? We’ll explore all of this next week, so stay tuned!

Low Carb Diets

Low body weight has become a body ideal for western society recently, and with that ideal came the diet craze. Juice diets, low fat diets, low calorie diets and low carb diets became more and more popular. Since we talked a bit about burning fat last week (while you’re sleeping, best diet ever I’d say), I thought I’d explore low carb diets today.

What is a low carb diet?

This diet is when you restrict the amount of carbohydrates you consume. Carbohydrates are in the form of sugars, pastas, bread, etc.  Foods that have a lot of carbohydrates are replaced with foods with high fat and/or protein content, though usually just the latter on its own. These diets can be used to treat obesity and diabetes (lower sugar content in the diet).

How does it work to reduce weight?

Last week, we talked about morning breath and the production of those smelly ketones when your body has burned all of your sugars and begins to burn fat. Now, what if you don’t ingest that many sugars, or carbohydrates, in the first place?

Much like when we sleep, our bodies burn more fats when we consume less sugars. If you ingest less sugars, you’ll have less sugars to oxidize to produce energy. Your body’s stores of sugars will be oxidized faster, leaving our bodies to resort to burning fat to keep obtaining energy. And that’s how you can lose weight with this diet!

More about ketones

At first, this will result in more ketones (a byproduct of fat metabolism during fasting conditions) due to the sudden change in diet from higher amounts of carbohydrates to lower amounts.

Eventually, ketone production may go down if the state of low carbohydrates is no longer be recognized as a state of fasting for your body. But if you keep reducing your intake of carbohydrates, then you will increase your ketone production, which can be hazardous to other metabolic processes in your body.

Ketones are acidic and can raise the acidity of your blood if in high concentration. If it is in a low concentration, however, your buffer system in the blood will maintain the acidity of your blood at a healthy level.