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Medical Are there any other Macronutrients?

  1. Feb 18, 2017 #1
    I have a few questions on energy from foods. Do we have any other macronutrients that contribute energy to the body other than carbohydrates, proteins and fats in our body? What is the role of Hydrochloric acid (HCL) in our stomach? Is the HCL involved in all three above macronutrient digestion?
  2. jcsd
  3. Feb 19, 2017 #2

    jim mcnamara

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    Staff: Mentor

    Macronutrients are: Water (non-caloric), fats, carbohydrates, and proteins. All of these provide basic building 'materials' for all of the functions your body does for homeostasis, and daily tissue building/repair.

    Approximate caloric values:
    Water: Zero
    Fats: 9 kCal/g
    Carbohydrates: 5 kCal/g
    Protein: 5 kCal/g

    HCl is produced in the stomach to hydrolyze proteins (break them down into amino acids) primarily. And to provide a low pH environment favorable to enzyme activity there.
    Acidity also facilitates absorption of some micronutrients in the intestine.

    Fat digestion/absorption depends on bile production in the liver, carbohydrates break down into simple sugars in the presence of enzymes and bacteria. They can move though most of the mucosal membranes in the digestive tract. Acidity may play a small role. Ex: you can absorb glucose from fruit juice into your bloodstream in your mouth. Insulin dependent diabetics use fructose/glucose tablets to raise bad, low blood sugar levels by dissolving them in the mouth. This fast uptake of simple sugars is often discussed in the context of glycemic load and glycemic index.

    Lower acid levels in the stomach (ex: antacid medicines or advanced age) may require supplementation or diet change. For example, Calcium citrate is sometimes preferred as a calcium supplement for older patients with problems like osteoporosis. It is better absorbed in a higher pH gut. I am oversimplifying here, as there may be a LOT of other issues involved, but the mian idea is that some citrate salts are better absorbed in people with low acid levels.

    Diet is a factor on intestinal pH levels.

    Here is a very interesting review of papers on the effects of changing:
    pH, sodium, potassium, chloride, and carbonate levels
    of humans diets over the past 200 years.

    Note the complete reversal of potassium to sodium ratios.
    Then: ~ 10 Potassium: 1 sodium
    Now: ~ 1 Potassium: 3 sodium
    The ~ character means 'approximately'
    Chloride has also become far more prevalent.
    Last edited: Feb 19, 2017
  4. Feb 19, 2017 #3
    Fats, carbohydrates and proteins provide all the energy and essential raw materials that our bodies require.
    In addition to those we also need some vitamins and trace elements, but these are not energy sources.
    They are needed in small quantities for some particular part of body chemistry.
    For example we need iron for our red blood cells, vitamin C is necessary for a number of body repair and maintenance functions,
    There is usually enough of these trace requirements present in food along with the three major categories
  5. Feb 21, 2017 #4
    Thanks Jim and rootone.
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