Exam about Nutrition, only chat me if you’re Nutrition major or related to NUTR

I. Water
A. Functions

1. Heat capacity/temperature stabilization

2. Evaporative cooling

3. Medium for chemical reactions (metabolism)

4. pH balance

5. Shock absorption

B. Water loss

1. Water lost constantly—evaporation (lungs and skin)

Lost periodically—urine, perspiration, feces

2. Amount lost varies; typically, about 1-2 liter through urine, 1-1.5 through other means. Factors that increase water loss:

3. Replaced by drinking, eating, metabolism (minimal)

C. Where water is

a. Water in the body is divided between intracellular and extracellular water

1. Intracellular: inside of cells

2. Extracellular: outside of cells; insterstitial space (in-between cells) and blood plasma are the primary areas. Another important compartment is in the kidney tubules, where urine is being made.

b. Cells maintain specific concentrations of specific electrolytes both inside of them and in the interstitium; for example, there is always a higher concentration of K+ inside of cells than outside; and the opposite is true for Na+.

c. The water volume, and the concentration of electrolytes (minerals and proteins), is carefully controlled in all of these spaces.

-Electrolytes attract water; but Na+ is one of the strongest attractors: “water follows sodium.” Cells can use this fact. Cells cannot move water directly, but they can move Na+. So, if a bunch of Na+ moves into the blood from kidney tubules, for example, water will follow the Na+ and your urine will be more concentrate (and your blood volume will increase).

D. Water Balance- how we make sure that we don’t lose more water than we take in (kidney control, thirst and reabsorption at the large intestine are the primary mechanisms

a. Via kidneys: Kidneys are filtering blood plasma constantly, and urine consists of a sample of your blood plasma. The cells of the kidney tubules have the ability to keep substances in the blood, or allow those substances to go into the urine as waste. Kidneys can also adjust how much water is lost into the urine.

If you are losing water, your blood volume (and pressure) will decrease. Hormones will tell your kidneys to concentrate the urine, allowing more water to stay in the blood. Since water follows sodium, the kidneys will also retain sodium to help maximize water retention in the blood. The primary hormones that cause Na+ and water retention are aldosterone (Na+) and AntiDiureticHormone (ADH).

When you have very yellow urine, this is a sign that your kidneys are retaining lots of water. If this happens often, it is a sign that you should increase your water consumption in general.

b. Thirst: you get thirsty when-

1. Blood has a high sodium concentration

2. There is a decrease in blood volume and pressure

3. There is dryness of the upper GI tract.

c. Reabsorption at the large intestine

1. When water is plentiful, feces spends less time in large intestine

2. When dehydrated, large intestine hangs onto feces longer to reabsorb as much water as possible –> constipation

d. Substances affecting fluid balance

-alcohol and caffeine both inhibit ADH… so, do you urinate more or less when you have alcohol/caffeine? Why might you get dehydrated when you drink a lot of alcohol?

e. Dehydration

1. Chronic, slight dehydration- can increase risk of kidney stones, possibly negatively affect kidney function, cause retention of toxic wastes, possibly contribute to some cancers

2. Severe dehydration- fatal within days

f. Water intoxication- also fatal!

II. Minerals

A. General/background

a. Inorganic, generally single elements

b. Not destroyed by heat, pH, etc.

c. Dissolve in water as electrolytes (ex, NaCl); they are water-soluble

d. Bioavailability- a number of factors can affect it, but here are a couple of big ones:

i. 2+ charged can interfere with each others’ absorption… this is only an issue with supplementation. So, for example, if you are taking Mg2+ supplements during a meal, you might reduce your absorption of Ca2+ and Fe2+, etc. The major 2+ minerals are the ones I just mentioned, also zinc, copper and selenium. *Lead is also a 2+ metal, but is a toxin. Why might adequate intake of the 2+ minerals help reduce effects of lead exposure?

ii. Plants contain organic acids that can bind minerals and prevent absorption: phytates (whole grains) and oxalates (spinach, tea, chocolate). Keep eating your whole foods… if you get enough of the minerals, especially if you include some non-plant sources, you should get enough.

iii. Fiber can also bind minerals and prevent absorption.

iv. Amounts in plant foods can vary widely, depending on the soil the plant was grown in. For example, soils in the Midwest are notoriously low in iodine, and goiter was a common disease in the Midwest before salt was regularly iodized.

e. Major vs. Trace minerals

i. Major- need more than 100 mg daily: sodium (Na+), potassium (K+), Chloride (Cl-), phosphorus (as phosphate, PO4 3-), magnesium (Mg2+), Sulfur (as sulfate SO3 2- or part of other molecules like amino acids)

ii. Trace- need less, but they are no less important!!! Ex- iron is a trace mineral, but still very important. Iron (Fe 2+), Zinc (Zn2+), Selenium, Iodine, Copper, Manganese, Fluoride, Chromium, Molybdenum

B. Minerals with big involvement in bone health:

a. Calcium, Magnesium, Fluoride, Phosphorus

C. Minerals… blood health:

a. Iron (iron is part of hemoglobin, which carries oxygen), calcium (calcium is required for blood clotting), zinc (helps regulate blood pH), copper

D. Minerals… neural and muscle function

a. Sodium, potassium, chloride, calcium

E. Minerals that affect blood pressure (know HOW they affect blood pressure, in terms of increasing/decreasing)

a. Sodium, potassium (stronger correlation between low K+ and hypertension than high Na+ and hypertension!), calcium, magnesium

F. Minerals…metabolism

a. Chromium, molybdenum, iron, manganese, zinc, iodine (iodine is part of thyroid hormone)

G. Minerals… immune function

a. Zinc, selenium

H. Minerals that have antioxidant functions, or work in antioxidant systems:

a. Selenium, zinc, copper

I. Some specific details:

a. Calcium regulation: calcium is absolutely vital for keeping you alive second by second. Its roles in neural and muscular function, in blood clotting, in cell communication, and a variety of other phenomena mean that if blood Ca2+ goes too high or too low, you die. Blood Ca2+ levels are tightly regulated within a small range. Bone calcium is a reserve; bones can spare calcium when the body needs it. Here is a brief and simplified overview of how calcium is regulated:

i. When blood calcium levels rise, and you are an adult, some goes into the bones. The remainder of excess goes into your urine.

ii. When blood calcium levels fall,

1. Parathyroid hormone is released from the parathyroid glands;

2. Calcitriol is activated by the kidneys

3. PTH causes bones to break down some calcium crystals, releasing calcium to the blood.

4. Calcitriol… well, you know what that does!

iii. Note: calcium supplements have NOT been shown to reduce occurance of fractures; in fact, they tend to show increase of fracture risk. Additionally, a large recent study has shown increased risk of heart disease with long-term high-dose calcium supplements. Keep your dosage low, and get most of your calcium from food! A vitamin D supplement is a good idea, too.

b. Processing and Na:K- when foods are processed, like Twinkies, the ratio of Na+ to K+ goes up. That is, too much Na+, too little K+. Many of us face the risk of low-level chronic K+ deficiencies. It is widespread in whole foods, but you really need a lot of it. Eat your whole foods! Notable sources of potassium besides bananas: mushrooms, coconut water, buttermilk, potatoes (with skin).

*Low potassium intake has just a stronger association with high blood pressure than does high sodium intake!

*The primary source of sodium in the North American diet is PROCESSED FOOD, not salt from the salt shaker. To reduce your intake of Na+ (and simultaneously increase K+), start with reducing processed foods.

c. Phosphorus, in addition to its role as part of calcium crystals, is part of phospholipids, ATP, and DNA

d. Iron: heme vs. non-heme, vitamin C, absorption and recycling:

i. Heme-iron comes from animal sources; it is iron attached to heme (as in hemoglobin). It is much more bioavailable than non-heme iron, which is how iron from plants exists.

ii. Vitamin C, taken with iron-rich foods, increases absorption of iron. This is especially important for people at risk of iron deficiency: vegetarians and women.

iii. Iron absorption and cycling:

1. Iron is absorbed through channels in enterocytes, like most water-soluble nutrients.

2. In the enterocyte, it is bound to the protein ferritin for storage in the enterocyte. If it is not needed, it will go out with feces when the enterocyte is shed. If iron is needed, it will be put onto another protein called transferrin, and then released to the blood.

3. Transferrin shuttles iron to the liver or the bone marrow. It will be used to make blood in the marrow; it will be stored in the liver, attached to the ferritin. If it needs to be released, it will be attached to transferrin.

4. Iron is recycled. When red blood cells die, immune cells capture the iron, attach it to transferrin, so that it can go back to the liver or marrow.

e. Iodine, thyroid hormone and goiter

i. Iodine is part of the structure of thyroid hormone. If someone has an iodine deficiency, the thyroid hormone gets made in the thyroid gland but will not be let go. The thyroid gland keeps making more… but not letting go…. So the thyroid gland grows into a big goiter!

J. Deficiencies and toxicities- Please know for Na+, K+, Ca2+, Fe2+, Zn2+, iodine, fluoride, copper, selenium. Know common causes (besides just dietary deficiency or over-supplementation) and symptoms.

K. Food sources- in general, assume animal sources are more reliable than plant sources (primarily because plant sources vary based on soil), but here are some notables that I want you to know specifically (keep in mind these are short lists, you can find other good sources of each for your own interest):

a. Calcium- dairy, dark green leafies, legumes, tofu processed with calcium, bones (eaten with fish or cooked with food, as in soup bones), dark chocolate/cocoa, almonds, sesame seeds

b. Magnesium- nuts, legumes, whole grains, dark green leafies, seafood, chocolate/cocoa, bones (note: animal sources are NOT as important)

c. Sodium- most sodium in the North American diet comes from processed foods; natural sources include seafood and soy sauce

d. Iron- meats, legumes, dark chocolate/cocoa (you see what I’m getting at with all the dark chocolate, right?)- dairy is NOT a good source of iron

e. Zinc- meats, seafood, eggs, legumes, whole grains; but oxalates and phytates do reduce zinc absorption, also soil quality has a huge impact on zinc content of plants; vegetarians should be mindful of zinc intake.

f. Selenium- meats, seafood; plants vary WIDELY based on soil content. Vegetarians should be mindful of selenium intake.

g. Potassium- whole, minimally processed foods- widely distributed among both plant and animal sources, though fresh plant foods are your best bet. While most whole foods have it, we need a LOT of it, so it is important to eat MOSTLY whole foods and save processed/junk foods for occasional treats or conveniences.

L. Minerals on Food Labels

A. Nutrient Facts Panel: The only minerals that are REQUIRED to be shown on the NFP are sodium, iron and calcium. Sodium is reported in both milligrams (mg) and %DV; iron and calcium are reported in %DV. However, most foods contain more vitamins and minerals than just those, even if the manufacturer doesn’t report them. That means for example, on a bag of nuts you probably won’t see magnesium reported; but, nuts are a great source of magnesium and there is definitely some in them. The manufacturer has simply chosen not to report the magnesium (or most of the other vitamins and minerals the food contains).

B. Ingredients List: Typically, when minerals are on an ingredients list, they are listed as part of mineral salts: combinations of positive and negative minerals. Minerals listed on ingredients lists are NOT whole foods sources; they are essentially just supplements added to the food. Minerals are usually added to prepared foods for one primary reason:

a. To fortify a processed food and make it seem healthier than it is,

i. For example, here is a list of some of the minerals on a PopTart label: reduced iron, tricalcium phosphate

ii. What minerals is this food fortified with?

If you see an ingredients list with a long list of minerals, that can be a RED FLAG that says “this is probably a highly processed junk food!”

III. Herbal Supplements:

Please understand the general risks and benefits of trying herbal supplements. Also know these specific herbals, what each of these might help with, whether there is evidence to support the claims (ie, do we really know if it works), and what the side effects (if any) are:

1. Chamomile

2. Echinacea

3. Ephedra

4. Ginkgo

5. Valerian

IV. Phytochemicals

Know the names, GENERAL benefits (ex, for those that reduce cancer risk, know reduces risk of cancer… but not HOW that risk is reduced) and main food sources of:

a. Capsaicin

b. Carotenoids, specifically lycopene and beta-carotene

 
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