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9

does the microbiome affect food metabolism? Most definitely (and not surprisingly). The Arumugam paper [1] notes that The drivers of [enterotype 1] seem to derive energy primarily from carbohydrates and proteins through fermentation, … because genes encoding enzymes involved in the degradation of these substrates (galactosidases, hexosaminidases, ...


8

Bioavailability is a concept which applies to nutrients and drugs which pass through first-pass metabolism, i.e. orally (and to some extent nasally) consumed substances. Anything absorbed in the gut first passes through the liver before reaching the rest of the circulation, and both the gut and liver may metabolise it to some extent. The liver in specific ...


7

Shortest answer: there's nothing special in human biology, you could totally make it Short answer: Bachelor chow! I would totally buy this stuff if they made it. The closest I have now to bland, flavorless, zero thought/effort food is Wheaties. longer answer: Seriously though, dogfood for humans wouldn't be that hard to make. If you just took everything ...


6

Yes. Rob Rhinehart has developed what he refers to as "a food substitute intended to supply all of a human body's daily nutritional needs, made from powdered starch, rice protein, olive oil, and raw chemical powders" which he calls Soylent. It was developed and tested largely in 2013, crowdfunded late 2013, and is expected to start shipping in 2014. Tests ...


6

Yes, the microbiome affects food metabolism and the diet affects the composition of the microbiome. +1 to Konrad for his response. This is an area of research in which I and colleagues are engaged. Frankly, it is easier to assess the changes to the microbiome based on diet rather than looking at the fecal material to determine (unused) metabolic energy or ...


5

The quantity of nutrients the body requires takes much more physical space than can be included in a simple pill or injection (used only a few times a day). But nutrition can be provided by IV (intravenous administration), and it is used today for some medical conditions. When the IV completely substitutes for normal digestion, it is called total ...


5

No it is not possible. Humans are heterotrophic organisms, which means that we use organic molecules (i.e., food) as a source of nutrients and energy. We use the nutrients to add mass to our bodies. These nutrients are the familiar carbohydrates, proteins, lipids (fats), etc... During digestion food is broken down into simpler organic nutrient molecules ...


4

For what concerns amino acids, mice rapidly reject meals that are not balanced in essential amino acids and continue to look for other kind of foods. This behavior is called aversion response and it is an adaptive phenomena that can be observed already 20 minutes after exposure to the unbalanced food. The mechanism involves brain sensing of uncharged tRNAs. ...


4

Much like Daniel Standage suggests, I think "edible" is more inferried than defined, sort of like looking at a black hole - its absence is defined by the activity around it. Human bodies are capable of metabolizing lots of compounds that become poisonous pass some threshold. In medical terms there are LDmin and MLD and LD50: miminum Lethal Dose, Median ...


4

As far as I know, edibility (wow, I'm surprised that passes the spell checker!) is not a strictly defined term, biologically or otherwise. Humans have been around eating and drinking stuff long before the scientific method was around to study this question rigorously, and before there were regulatory agencies charged with approving new products as "safe." As ...


4

It isn't burning of the calorie you should consider as once digested different calories are stored in the same manner, it is actually the digestion itself. Proteins are by far the most energy requiring foods to digest such that around 20% of the calories in proteins are used in extracting them. In comparison carbohydrates are much easier at around 5-10% ...


4

Broadly speaking, nutrients that enter the blood from the gut, and those that are released into the blood by the liver, are available to any cells that require them. So there is no "guiding to the correct location" in the sense that you suggest. Lipids for example are present in the various lipoproteins and can be acquired from these by all cells. Iron is ...


4

The mineral content in tap water differs from area to area as well as the source. The mineral content in bottled water is regulated by the companies that manufacture them, in particular the Mg and Ca content(reference). Death rates tend to be lower in areas with tap water containing higher levels of Ca and Mg. It has been shown that deficiencies in ...


3

The first answer is that humans cannot. Chitin is a major component of the exoskeleton of insects and other arthropods, the cell wall of fungi and bacteria, the perisarco of hydroids and is also present in the epidermal cuticle or other surface structures of many other invertebrates. After cellulose, chitin is the most abundant naturally occurring ...


3

According to @Ilmari Karonen's comment and link, I have the answer. Such food does exist. However a person who tried to eat it and nothing else could bear it for only 7 days. He had cravings for "normal" food. The link was http://www.angryman.ca/monkey.html. Apparently the guy had weak will, but that's normal.


3

I'm not quite sure what you mean by regardless of x and y being out of balance. Surely it would make more sense to assume you gain 0 weight if x and y are balanced? The prime reason why people get obese is probably because x and y are not balanced for them (there are other reasons though, as well as reasons why people can have it imbalanced and still ...


3

Essential "minerals", i.e., metal cations are magnesium, zinc, iron, potassium, sodium, manganese, molybdenum, selenium, cobalt, copper and even calcium, as we lose a tiny amount of it through urine and sweat. They are all "stored" in some way, but only temporally, so some amount has to be taken up daily. It would show only weeks later, however, if you have ...


3

Whether using quantitative models, or "animal models", I think this is a useful quote to keep in mind: A model is a lie that helps you see the truth. -- Howard Skipper As for evidence that using mice models for human nutrition is justified -- I believe there has been a good deal of research that has provided useful insight on the influence of ...


3

Does this look like the same bug to you ? . This one is a bulb mite, Rhizoglyphus robini, see here.


3

There are no essential sugars. In the context of nutrition "essential" usually means "must be obtained from the diet". So for example the amino acid methionine is an essential amino acid (for humans). Within this definition there are zero essential sugars. A Google search for essential sugars reveals lots of sites like this one. The site lists glucose as ...


3

No, there isn't a single diet that can be recommended from a biological perspective. The most popular diet from a pseudo-scientific perspective is the Paleo diet, saying we should eat what our ancestors in the Paleolithic were eating, but it makes a mistake of forgetting that our metabolism has evolved since then. There are also numerous other flaws in the ...


3

In short; yes. It depends on the breed (not all lay up to 1 egg/day), the age of the bird and on nutrition. High yielding breeds of chicken are e.g. dependent on supplements of calcium to be able to produce new shells rapidly (e.g. in the form of ground-up shells). Some information on the nutrient requirements of chicken can be found at Feeding the Laying ...


3

Is this possible or am I just hallucinating? Certainly possible, but I'd peg the mechanism closer to Sensitization or De-sensitization of the neurons involved so that when you finally ingest some salt the sensation is different. The sodium and chloride levels of the ingested material wouldn't have a direct effect on the level of De-/Sensitization, but ...


2

The phosphoric acid in cola will contribute to dietary intake of phosphate. I may be missing something, but, since the transporter functions to reabsorb phosphate that has been filtered out at the glomerulus, excess phosphate will spill over into the urine. According to Wikipedia the RDA for phosphorus is 700 mg and the tolerable upper intake level is 4000 ...


2

Cellulose is one of the most common sources of fiber in the nutritional sense. Because oranges are plants, their cells have cell walls, made out of cellulose, so some of the fiber in an orange is surrounding each individual cell. Both vascular cells and pith cells tend to have particularly thick cell walls, so they are probably higher in fiber (this article ...


2

This is a bit hard because the usual composition statements are a combination of different types of molecules. Most of faeces are, by dry weight, bacteria (30%), undigested food and fiber (30%), fat (10%-20%), inorganic matter( 10-20%), other protein(2-3%). (reference) As you can see the bacterial portion contains proteins (amino acids) and other types of ...


2

My impression is that the use of mice as human models for anything is primarily the result of historical precedent. A lot of work has been done to breed different lines of mice for particular purposes, and a lot of related methodology has therefore been established. Similarly, a lot of comparative genetic/genomic work has been done to characterize ...


2

One rationale is that smaller meals will cause less insulin secretion compared to a larger meal. With less circulating insulin over the time, insulin will be under the threshold required to activate the adipogenic program in the white adipose tissue. So, you will burn ingested carbohydrates instead of converting them in fat despite the same caloric intake. ...


2

@fileunderwater's suggestion to use a scale is probably the best answer you could get, but looking at this broadly, the answer is no. The oft-referenced apple and pear shapes are indeed very real and have medical consequences. One of the issues is that there are sex differences in fat distribution. There is no evidence I can find that finger fat is a good ...


2

Perhaps someone else can answer this with more certainty, but I'd guess that because raphides are essentially sharp crystals that cause irritation-related symptoms, rather than toxic chemicals in the way one might usually think of them, that drinking the water wouldn't pose a problem (actually, I suppose the word "insoluble" might be a clue here). Raphides ...



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