This week on the Petri Dish:
Science News (at 1:57 on the podcast)
Science Controversy: Are carbs the enemy? (6:00)
Science Myth: Vegetarianism is bad for you (14:37)
Remember This Fact?: How do we taste? (22:39)
Film of the Week: The Nutty Professor (26:25)
Carbs vs FatsFats and carbs are both digestible for energy, which is because they are long chains of carbon molecules and hydrogen along them, which, when digested become carbon dioxide, the same stuff cars make. but the 2 different shapes have different properties. Fats are the simplest as they are 2 long chains like legs negatively charged, and so group together, into sheets, and congregate like crowds.
The most basic of these are the saturated fats, which are like people standing arms and legs held together, meaning that they can all stand closer together, meaning that if your trying to walk through the crowd its harder to push through, and because their all pushed so close together they make a thicker layer as they push up, and so its for transferal from thing from the floor to the surface.
This is why there is such a push against saturated fats, because this rigidity, and inability to allow for molecules to move from the bottom to the top OR VICE VERSA. Due to this too many saturated fats, can lead to weakening of the heart due to having to force against this inflexibility, and puts pressure on the neurons in the brain because of a decrease in plasticity.
Unsaturated fats are like saturated ones but there is a kink in the legs, so its like they’re standing with their legs out. Which puts more space between each of the people. And so it would be easier to walk between them as there is the extra space between them, allowing for better flow through them, and if you dropped your phone you would be able to pick it up and hold it to your head. this extra flexibility adds plasticity.
The OMEGA3 and OMEGA6 oils are fats which have these kinks at the 3rd and sixth Carbon, which is why they are good for your heart, and there was such a fuss over them. they decrease pressure on your heart, allowing for easier beats, and when trying to form new memories, the new connections are easier to produce.
The new "evil fat", the trans fats are called so because they are transition fats, its because they have a load of kinks in them, and because of this they can fold up into cholesterol. what these do in pretty much fold up and connect in the middle making a ring. when they are in the crowd of fats, they are like a short fat person pushing around, mixing up the crowd faster, and so increases the flow of the crowd as they step around, and can even make the saturated fats act like unsaturated fats, with increased plasticity. but when they get together, because they don't have the differing polar head, they congregate, and even if they are flowing past, in the blood, can attach from the outside of the cell. causing arteriole plaques. these trigger immune reactions of white blood cells attaching to remove them, giving addition to the plaques. these can build up until stop the flow of blood which is why cholesterol can cause heart attacks.
Carbohydrates are also used for energy storage, but they are much shorter in their length, only 6Carbons around instead of 12 to 14 like fats, but because they are round and have OH attached to the Carbons they have an easier to attain energy supply and harder to store energy supply. so they are used preferentially to fats. Single carbohydrates are sugars that taste sweet because they are a quick release of energy, and starchy tasting foods are because there are rows of the carbohydrate molecules. These are for storage of them over long periods of times, and so give them a low G.I., which is a glutamic index. This means that the energy released from these are over a long period of time, so there isn't an instant energy hit, which wears off making you hungrier, but its released over a long period of time.
The carbohydrates are placed in strait lines in people, but in vegetables, leaves and grass, the plants have these carbohydrates compacted even more, by branching off all over the chain into a matrix. Our digestive enzymes aren't able to break these complex molecules down in our digestive systems. This is where dietary fiber comes from, and the more of this we eat the faster our bowl movements. And if we eat a high enough diet we can speed out bowl movements up to 12hours from the usual 26-32hours in Europeans.
Hi Carb Low Carb DietsWhat is a High Carb Low carb diet?
A high carb diet is where protein and fat intake is decreased, and so their is a minimalism in meats and an increase in food and high in carbohydrates, so generally white things like rice, bread, pasta.
Low protein diets, have a decrease in rice bread and pasta, and so foods high in fibre, protein and fat replace it. so generally meat and roughage in these sorts of diet. Also means or peas, which are generally, low in carbohydrates.
Both the high carb diets and the low carb diets are used as weight loss techniques, and it is because your body burns carbs first, and then fats, then proteins. So if you increase your carbohydrate input and lower your fat input, your body doesn’t have the fats for storage, and to form them has to burn up carbohydrates to convert them.
In a low carb diet, there isn’t the carbs to burn, so fat gets burnt first and then protein. Due to the different digestive properties of these they have differing effects on the body which means that the effect on the body is to decrease the energy input.
The studyIn the this Australian study published in the British journal of nutrition they studied both hi and low carb diets in obese people, and observed which is healthier. So specialized diets where set up for the 2 groups and they were monitored over 8 weeks.
the major difference was there was a major decrease in the number of bowl movements (times gone to the bathroom), the mass excreted, and the concentration of butyrate. also there was a decrease in bifidobacteria. This is because this is a bacteria which eats the extra carbohydrates left over in the bowl. These as assumed increased hi-carb diet, but the weird stuff is the things that were the same for both the hi-carb and low carb diet.
The faecal form (colour and shape) pH, ammonia concentration and E.coli did not change. the reason that the faecal form is important is because it displays the health of the intestinal tract, and it was thought that the stool would get darker and greasier in the LC diet. Also when proteins are broken down ammonia is released, but this wasn’t being excreted through the faecal matter, as well as there being no increase in pH, showing that homeostasis keeps most of this under control.
there was no difference between incidence of adverse gastrointestinal symptoms, but with the LC diet there was deteriation in the concentration and excretion of faecal SFCA which is important for immunity cells of the GI tract, in fighting colorectal cancers, also a lowered stool weight, suggesting that there could be long term issues with a LC diet.
Overall the LC diet had faster weight loss compared to the HC diet, but for the long-term the LC diet can be detrimental. part of this is due to the low fibre content of the LC diet. There were no reported such as abdominal pain, or constipation, bloating or excessive flatulence. The decrease in bowl movement time in both diet means that there is an increase in the chance of bowl cancer, because slowed bowl movements means that cells in your bowl have more exposure to chemicals.
Gut transit is not effected by diet.
Reduced memory?One week after starting a weight loss diet that severely restricted carbohydrates, participants in the Tufts University study performed significantly worse on memory tests than participants who followed a low calorie, high-carbohydrate diet. The low-carb dieters' memory-test performances improved in the following weeks after they began eating some carbohydrates.
The study: 19 women between the ages of 22 to 55 who were closely followed after beginning a low-carb weight loss plan similar to the Atkins diet includes plenty of fruits, vegetables, and whole grains.
Before starting the diets, the women underwent testing designed to measure long- and short-term memory and attention. The tests were repeated one, two, and three weeks after the diet began.
The study is published in the February 2009 issue of the journal Appetite.
Increased memory?In a study published in 2007, Brinkworth and colleagues performed cognitive function testing on dieters after they had been on either a low-carb or high-carb weight-loss diet for eight weeks. Both groups lost weight and showed improvements in mood.
The low-carbohydrate dieters showed slight impairments in cognitive processing speed, but no difference was recorded between the two groups in working memory. Brinkworth says if eliminating carbohydrates from the diet does affect memory, the effect may only be temporary.
Why would this happen? Carbs Are Brain Fuel
The body breaks carbohydrates into glucose, which it uses to fuel brain activity.
Proteins break down into glycogen, which can also be used for fuel by the brain, but not as efficiently as glucose.
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