50 votes
Accepted

Why are prions in animal diets not destroyed by the digestive system?

Proteases are enzymes in your digestive system that help break down food, acting like molecular-sized scissors that cut up proteins. Proteases have clefts, or subpockets, into which proteins fit, ...
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47 votes
Accepted

Why are sugars in whole fruits not digested the same way sugars in juice are?

Sugars in 100% natural fruit juices are chemically the same as in whole fruits. They mainly include glucose, fructose and sucrose: Apple nutrition data (expand the carbohydrate section) Apple juice ...
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  • 7,949
27 votes
Accepted

How can birds disperse seeds when they are able to digest them?

Birds may indeed digest seeds under conditions of rest. It has been postulated that almost all current knowledge on mechanisms of internal seed dispersal has been obtained from experiments with ...
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26 votes

Why is wombat scat (feces) shaped like cubes?

I'm almost certain that your question is based on the press that Patricia J Yang's research is receiving (e.g., here and here). Yang and her co-authors examined the structure and mechanics of some ...
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10 votes
Accepted

Does a walk after a meal help with digestion?

apparently walking helps in the movement of food into the stomach and improves digestion. Also helps in decreasing blood sugar after meals, which decreases cardiovascular risk and potential signal ...
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10 votes
Accepted

What happens to lactic acid I eat?

First, there are two different isomers of the lactic acid, the L(+)- and the D(-)-form. Both differ in the position of the OH-group in the molecule: Both turn polarized light in different ways, the D(...
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10 votes

Does freezing microorganisms such as probiotics kill them?

Yes, they do. For a look at survival of Lactobacillus and other bacterial species after multiple freeze/thaw cycles, check out Harrison 1955 (below). The awesome hand-drawn graphs show that many ...
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  • 3,254
9 votes

Why do we get sleeply after we eat?

After we have eaten... the maximum blood supply is transferred towards the digestive system so that digestion is done, and therefore the brain to does not get adequate blood supply. Am I right about ...
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9 votes
Accepted

Why do feces vary so little in color?

The main reason for the color of our stool (or feces) is the presence of bilirubin, a breakdown product of the hemoglobin. The amount of it causes different variations from yellow to dark brown. When ...
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9 votes

Why is wombat scat (feces) shaped like cubes?

On a more serious note than my comment, and as a supplement to theforestecologist's answer, it's worth pointing out that a cube with rounded corners and edges has larger surface area to volume ratio ...
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9 votes

Do sharks fart?

Excellent question. Via Southern Fried Science: According to Daniella Rabaiotti, a postdoctoral researcher at the Zoological Society of London, sand tiger sharks are the only shark known to fart. They ...
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8 votes
Accepted

Why are triacylglycerols broken down before being absorbed?

Your question does not have a clear answer yet, as stated in Metabolic regulation: a human perspective / Keith N. Frayn. – 3rd ed (2010) on page 39. There is still debate about how fatty acids ...
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  • 256
8 votes
Accepted

Why aren't the antibodies in the mother's milk digested by the infant's digestive system?

Demers-Mathieu et al. 1 used ELISA to quantify immunoglobulin concentrations from milk after 2 hours of digestion in the stomachs of preterm-delivered and term-delivered infants. From the abstract: ...
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  • 7,119
7 votes
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What are the consequences of drinking water with food?

A moderate amount of water while eating will not dilute digestion ...according to Michael F. Picco, M.D. and the Mayo Clinic: There's no concern that water will dilute the digestive juices or ...
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7 votes

Why are sugars in whole fruits not digested the same way sugars in juice are?

Drinking the juice without the fruit can easily lead to over-consumption. It is after all harder to eat four apples than drinking 500ml apple juice. As the liver breaks the fructose through ...
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7 votes
Accepted

Why is sugar absorbed very fast into the blood stream?

In short, sugars are absorbed quicker than proteins and fats because they pass through the stomach quicker and their digestion is simpler. Sugar can be absorbed through the mouth mucosa when applied ...
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6 votes
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why is cellulase not found in animals?

The answer to questions like this is just a guess (Primarily Opinion Based), and I've voted to close. But some food for thought too long for a comment: As it is really beneficial for all organisms.....
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6 votes
Accepted

Influence of eating at late night on sleep

According to Crispim et al 2011, caloric intake late at night is correlated negatively with sleep quality: We conclude that food intake during the nocturnal period is correlated with negative ...
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  • 3,254
6 votes
Accepted

Is plastic just as good for you as corn?

The part of the corn kernel that is visible in human feces is the outer coat of bran called the pericarp (see this image). This is a common structure in cereal grains like corn and wheat. However, ...
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6 votes
Accepted

How does horse extract the energy to needs from a relatively small digestive system?

The digestive system of a horse is by no means small: They have 15 to 21 m (50 to 70 ft) of small intestine, with a capacity of 38 to 45 L. They have a 1.2 m (4 ft) long caecum that holds 26 to 30 L. ...
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  • 2,472
6 votes

Human Digestion of Cellulose?

This isn't a complete answer, but searching Google Scholar for "Fibrobacter succinogenes human" I found this paper: The cellulose-degrading microbial community of the human gut varies according to ...
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  • 3,197
5 votes

How do people digest fat after gall bladder removal surgery?

This is not a problem, since the gall bladder "only" stores bile, but the production itself happens in the liver. There are some cases described which can get problems digesting very fatty food, but ...
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5 votes
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How does regurgitated food go to the 3rd stomach chamber instead of going to the 1st?

Your question supposes a very linear version of the flow of stomach contents of: 1->2->mouth->3->4 In reality, it is not so linear. Firstly some background: The rumen and reticulum form the first ...
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  • 166
5 votes

What happens to lactic acid I eat?

Lactic acid has been found to act as a fuel for the muscles. Refer to: http://www.nytimes.com/2006/05/16/health/nutrition/16run.html?_r=0 Most athletes consider lactic acid their enemy, and think ...
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  • 349
5 votes
Accepted

Can you eat enough to make your stomach explode?

Here's a simple cross-section of the stomach (from here): The stomach accomplishes much of its function by mechanically breaking down the swallowed food particles and mixing them with acid and ...
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  • 14.6k
5 votes
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Betaine HCl stomach pH

Betaine HCl (trimethylglycine) was present in over the counter "stomach acidifiers" but the US FDA says there is no evidence for its efficacy and has banned its use for this indication (source: US FDA)...
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5 votes

Can Fluoride be absorbed into the blood from within the mouth without swallowing?

Although I'm having a hard time finding a source that provides specific information on fluoride in toothpaste, this review explains that fluoride is most readily absorbed through intestinal epithelia ...
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  • 1,879
5 votes

Is sugar absorbed into the bloodstream through the walls of the mouth?

Simple sugars such as glucose, fructose and galactose will be absorbed. They are most probably transported by a common carrier, which is why if you present both glucose and galactose, the presence of ...
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  • 5,582
5 votes
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Do humans emit more carbon through respiration or defecation?

The short answer In a comparison between exhaled and faecal carbon, exhaled carbon wins. The long answer Warning: Assumptions, approximations and averages ahead. Calculating faecal carbon excretion ...
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