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

Vitamins

I. General- these are ideas to think about; for each vitamin, you will get more details later in the outline.

a. Structure- organic molecules, varied in structure. They are NOT polymers, and don’t require enzymatic digestion.

b. Functions- varied. Examples-

i. Attach to enzymes to activate them; ex-

1. The enzyme proline hydroxylase helps create the quaternary (functional) structure of collagen; it requires vitamin C (and iron) to be active…

2. B6 is part of the enzyme amino transferase… In this role, the vitamin attaches to part of a bigger molecule, a “coenzyme,” which activates the enzyme. The B6 coenzyme, for example, is Pyridoxal Phosphate.

ii. Participate/help with metabolism to produce ATP- we’ll see several ex of this later; but they do NOT contain kcalories.

iii. Other specific functions; ex, one role of V-A is to be excited by photons to help you see; V-E is an antioxidant; V-D is a hormone

c. Water-soluble vs Fat Soluble

i. Water: Bs and C

ii. Lipid: ADEK

iii. What does this mean in terms of how each is absorbed? Go over absorption of water-soluble vs fat-soluble nutrients again.

-why do you think people who have their gall bladders removed often develop deficiencies of the fat-soluble vitamins?

iv. Fat-solubles TEND to be stored better and TEND to have higher risks of toxicity. But there are exceptions to this. Excess water-solubles are generally excreted in the urine, if your kidneys can deal with them fast enough (ie, they come from food, not a pill)

v. The water-solubles leach out into water during cooking; this is why steaming is a good water-based cooking choice. When you boil, many of the vitamins go into the water.

d. Bioavailability, “life” and processing-

i. Life: All vitamins are vulnerable to degradation. Heat, light, and oxygen and time can all cause degradation. Different vitamins have different vulnerabilities; for example, C and E are especially vulnerable to cooking, while B12 is less so… with the exception of microwaving. In general, most of the vitamins are vulnerable to degradation by cooking to some degree.

ii. Processing tends to destroy and/or remove vitamins. Some are added back into processed foods (enrichment)

iii. Other factors- besides just the amount of vitamin in a food- can affect how much vitamin you actually absorb.

1. For example, spinach is an excellent source of calcium, but the oxalates in spinach bind calcium, so while there is a lot in it, you don’t actually absorb all of it.

2. Whole grains contain a lot of phytates, which also bind minerals such as zinc and reduce their overall bioavailability

iv. Some vitamins exist as “provitamins” in food- the form we eat is not active, but our cells can convert it to active vitamin: ex,

1. beta-carotene/V-A,

2. cholecalciferol/calcitriol (V-D)

e. Deficiencies and toxicities-

i. Deficiencies will cause widespread effects, but each vitamin deficiency will manifest specific symptoms reflecting one of its unique functions. Deficiencies may be caused by

1. inadequate intake,

2. disease that interferes with absorption (ex, celiac disease),

3. alcoholism,

4. parasite infestation,

5. and a variety of other causes.

Some vitamins have specific reasons for deficiency; for example, alcoholism especially affects folate and thiamin status.

ii. Toxicities- rare from food alone. However, toxicities- either sudden or chronic- may arise from over-supplementation. Supplements include pills, vitamin waters, energy bars, energy drinks, and fortified cereals.

iii. Many vitamin (and mineral) deficiencies cause anemia. Anemia is a broad term meaning that the blood isn’t delivering oxygen very well. There are many causes of anemia… so different vitamin/mineral deficiencies cause different types of anemia! (know the differences)

f. Many vitamins (and minerals, and phytochemicals, and provitamins) act as antioxidants. Here’s a summary of how antioxidants work:

i. The number of electrons surrounding molecules & atoms determine how stable they are

ii. Unstable molecules & atoms are highly reactive; react readily with other chemicals

iii. Highly reactive (unstable) molecules & atoms can cause harmful reactions with normal body chemicals

iv. Free radicals are highly reactive substances that steal electrons from other chemicals; now the other chemical is reactive because it is missing an electron

v. These types of reactions (stealing electrons) are oxidation reations; we say they cause oxidative damage.

vi. Free radicals can steal electrons from DNA, fatty acids in cell membranes, LDLs,, etc.

vii. Free radical action (oxidative damage) has been implicated in many chronic diseases: artherosclerosis, heart disease, cancers, etc.

viii. Free radicals are produced as biproducts/consequenses of normal cell activity. Free radical damage is thought to be one of the primary reasons that we age. Some environmental factors can increase free radicals (pollutants, smoke, etc.)

ix. Antioxidants are substances that donate electrons to free radicals, thereby stabilizing them, and preventing them from stealing electrons from important body chemicals.

x. Antioxidants are relatively stable with the “missing” electron. Various antioxidants work together to stabilize each other.

xi. Antioxidants protect our tissues from free radical damage; reducing our risk of developing chronic diseases… or at least buying us a few more years.

xii. Research into antioxidants as supplements has been disappointing. Supplements generally show no benefit at best; but alarmingly, sometimes show increased disease. For example, both beta-carotene and vitamin E are known to be antioxidants and to protect us from cancer when they come from food; but, when they are taken as supplements, they both increase the risk for cancer. It seems that antioxidants can become PRO-oxidants if you take too much. Whole food is your safest and most beneficial source.

g. The RDAs and ULs:

-I will be including those numbers in this outline; they are only for your reference. I’ll never ask you to remember the specific RDA, UL or DV for any vitamin or mineral. In case of an exception or two: if I do ever want you to know one of those numbers, I’ll make a big deal about it!

h. Fortification and Enrichment of prepared foods: please read in the text, be sure to understand the difference between “fortified” and “enriched.”

II. The water soluble vitamins

a. The B-vitamins: an overview-

i. All serve as coenzymes- know the names of the coenzymes!!!

ii. Each is somehow involved in ATP production, though they usually have other roles as well. Because of the ATP link, deficiency symptoms tend to be pretty widespread… if you don’t make enough ATP, ALL cells of the body are affected.

iii. The following outline leaves some subjects, specifically deficiency and toxicity, empty. I expect you to fill in these blanks in terms of what to know for the quiz/exam:

1. symptoms,

2. name of the disease if applicable,

3. why the disease develops (ex, not enough intake, alcholism, kidney dysfunction etc).

b. Thiamin (B1)-

i. Functions: part of Thiamin Pyrophosphate, a coenzyme needed for, among other things, decarboxylations during ATP production (basically, that means it’s important for making ATP), maintenance of neuron membranes

ii. Sources: widespread in whole foods, notable sources include pork, legumes, nuts and whole grains; fruits and veggies contain thiamin but are not notable sources. However, ample consumption of fruits and veggies will contribute significant amounts to the diet.

iii. Deficiency (two specific diseases):

iv. Toxicity- unknown

c. Riboflavin (B2)

i. Functions- part of FAD, a H (hydrogen atom) “shuttle van”- important for ATP production and other reactions

ii. Sources: widespread in whole foods, notable sources include dairy, egg, nuts, meat. Fruits and veggies contain riboflavin but are generally not notable sources. However, ample consumption of fruits and veggies will contribute significant amounts to the diet.

iii. Deficiency:

iv. Toxicity- unknown

d. Niacin (B3)

i. Functions- part of NAD, another H shuttle van- in addition to being used in ATP production, also needed for making fatty acids

ii. Sources: fruits and veggies contain some niacin, but primary sources are meat, whole grains, legumes and seeds.

iii. Defiency: (specific disease):

iv. Toxicity:

v. Of interest,

1. we can make a small amount of niacin from tryptophan

2. niacin in high doses can be part of a physician-overseen regimen to improve blood cholesterol.

e. Pantothenic acid

i. Functions: part of coenzymeA, which is a shuttle van for a piece of a molecule called “acetyl.” This is important for ATP production, and a variety of molecule synthesis reactions, like making certain neurotransmitters

ii. Sources- widespread in whole foods

iii. Deficiencies- unlikely

iv. Toxicity: unknown

f. Biotin

i. Functions: part of coenzymes that are involved in making molecules- ex, DNA

ii. Sources- widespread, but meat and fruit are notably lacking; your gut microflora generally make plenty to make up for dietary lack

iii. Deficiency:

iv. Toxicity: unknown

v. Of interest, raw egg whites contain a substance that prevents biotin absorption. Yolks, however, contain so MUCH biotin that if you eat both together you should still get plenty of biotin. However, it is possible for a person to face a biotin deficiency if they eat a whole bunch of raw egg whites daily without the yolks!

g. B6 (Pyridoxal)

i. Functions: part of PLP (PyridoxaL Phosphate), which activates enzymes that drive transamination and deamination reactions (making non-essential amino acids and using amino acids to make glucose… or other non-protein substances like niacin from tryptophan; also converts homocysteine to cysteine)

ii. Side note: homocysteine. Homocysteine is an amino acid derivative that has been correlated with an increased risk of cardiovascular disease (and likely has a causative effect). Three vitamins are especially important for keeping blood homocysteine levels low: B6, folate, and B12. They help to convert excess homocysteine into more benign amino acids such as cysteine.

iii. Sources: widespread in whole foods, but plant sources of B6 are less bioavailable than animal sources. Notable sources include meat, nuts, whole grains, and bananas.

iv. Deficiency:

v. Toxicity: for this one, look at the UL and compare it with vitamin supplements in addition to describing symptoms

-also, this B-vitamin is STORED in muscle tissue; therefore, more risk of toxicity than other B-vitamins

h. Folate/folic acid

i. Functions: part of TetraHydroFolicAcid (THFA)- important especially for the differentiation and maturation of new cells; therefore, REALLY important for fetal development, red blood cell production (they are constantly dying and being made anew), sperm production, GI tract maintenance, cell division in general, etc. THFA converts homocysteine to methionine, so is also important for reducing blood homocysteine.

ii. Sources: mostly whole PLANT foods! Animal foods are generally not good sources, with one exception: Egg yolks are also an excellent source. Notable sources include green leafy vegetables, avocadoes and legumes. The name “folate” actually derives from the word “foliage,” indicative that green leafies are a great source of this vitamin. This one is a vitamin that is harder to get enough of than other vitamins.

iii. Deficiency: in addition to what you will be looking for, note that a folate deficiency can lead to elevated homocysteine (what will that do?); also be sure to know the NAME and DESCRIPTION of the anemia caused by folate deficiency.

iv. Toxicity: POSSIBLY- increased risk of cancer with chronic high-level supplementation (hot off the presses research)

i. B12 (cyanocobalamin)

i. Functions: activates THFA… so all of folate’s functions apply to B12; also helps maintain the myelin sheath: insulation around neurons

ii. Sources: ANIMAL FOODS ONLY! Analogs in yeast and other fungi are not active.

iii. Deficiency: as you look at this, keep in mind that symptoms will be the same as folate deficiency, plus symptoms related to B12’s role in neural function.

iv. Toxicity: unknown

v. Of interest:

1. Requires INTRINSIC FACTOR to be absorbed: stomach cells make intrinsic factor, B12 binds intrinsic factor in the stomach; only when B12 is bound to intrinsic factor will it be absorbed.

2. Microwaving destroys it; stove/oven does not

3. Stored in the liver- possibly for years

4. Only bacteria can make cyanocobalamin! That includes the bacteria living in your large intestine; so… why do you need to eat B12? Why can’t you get it from your bacteria?

j. Vitamin C (ascorbic acid/erythorbic acid)

i. Functions

1. Antioxidant

2. Part of a coenzyme that is required for making collagen; collagen is a protein that holds us together… so if you don’t make enough collagen, you kind of fall apart (see symptoms of deficiency)

3. Enhances absorption of iron

4. Supports immune function

ii. Recommendations

1. Males 90 mg, females 75 mg

iii. Sources- fresh/frozen whole fruits and veggies!

1. Fresh fruits and veggies, potatoes; peppers, citrus and strawberries are notable sources.

2. Especially vulnerable to heat. Cooking reduces amount quite a bit; processed foods will have very little unless it is added back in

iv. Deficiency: (specific disease)- when you are looking at the symptoms, remember that many of the symptoms relate to its role in collagen production; without collagen, you fall apart.

v. Toxicity-

1. Extremely rare, but long-term use of megadoses can cause headache, kidney stones, and nausea. At high doses, it may also become a pro-oxidant, increasing risks of chronic disease.

2. UL- 2000 mg

III. The fat-soluble vitamins

a. Vitamin A: a fatty acid derivative

i. Active forms of V-A- “retinoids”

1. Retinol

2. Retinal

3. Retinoic acid

ii. How we get V-A from food:

1. Animal sources- as one of the active retinoids

2. Plant sources- as a precursor, or provitamin

-the provitamins of V-A are called “carotenoids”

-carotenoids are pigments ranging in color from yellow-red, and include xanthophylls, lutein, and beta-carotene.

-not all carotenoids can be converted to the retinoids; most beta-carotene is the most important carotenoid that can be converted to retinoids

iii. Retinoids are stored in the liver

iv. Functions of retinoids: each retinoid has a specific function. You don’t need to know which retinoid performs which function, just know that these are the functions of vitamin A. The exception to this will be retinAl’s role in vision.

1. Cell differentiation of epithelial cells (skin and other linings)

a. V-A helps to activate genes that will cause a cell to become unique; specifically, to become a cell that will line body surfaces and secrete mucous/oils

b. Deficiencies in V-A can lead to dry, cracked skin, dry eyes, reduced digestive tract function, too many keratinized cells, etc.

2. V-A plays roles in a variety of functions, including bone health, reproductive function and immune function

3. Vision:

a. Vision is “caused” when light travels to the back membrane of the eye, the retina.

b. The energy from light causes a series of reactions in the retina.

c. These reactions are monitored by nerves that send messages to the brain.

d. The brain translates those messages as “vision.”

e. The chemicals that react within the cells of the retina are:

i. Rhodopsin- in rod cells- excited by dim light (night/black & white vision)

ii. Iodopsin- in cone cells- excited by brighter light (color)

f. The basics of how vision occurs: Rhodopsin (rods) and Iodopsin (cones)- consist of retinal ( a form of vitaminA) bound to the protein, opsin. In the absence of light, retinal is in a cis (bent) conformation, and is folded into opsin. Light energy causes cis-retinal to spring open to a trans (straight) conformation, and retinal then detaches from opsin. This event alerts neurons, which will send a message to visual processing areas of the brain.

v. Functions of carotenoids: act as antioxidants

vi. Dietary recommendations-

1. Carotenoids are not converted 100% efficiently to retinoids, so amounts are reported in Retinol Activity Equivalents (RE): the amount needed to get 1 microgram of retinol

a. 12 mcg beta-carotene= 1 RE

b. adult male: 900 RE

c. adult female: 700 RE

2. Because of potential fatal toxicity and increased risk of cancer from supplements, whole foods should always be your primary source of both retinoids and carotenoids

vii. Sources

1. Animal (retinoids)- liver, egg yolks, animal fats including lard, tallow, dairy fat etc. NOT meat (muscle).

2. Plant (carotenoids)- yellow, orange, red and green plant foods are often excellent sources.

viii. Deficiency

1. Blindness, starting with night-blindness

2. Hyperkeratosis (see book for definition/description)

3. Other symptoms related to V-A’s widespread functions

ix. Toxicity of retinoids is fatal

1. UL: 3000 mcg/day of retinoids

2. Almost impossible from diet alone; some exceptions: you can overdose if you eat a LOT of liver, or take cod liver oil daily. Look for cod liver oil that has controlled amounts of V-A, especially for children.

3. It is nearly impossible to get classic V-A toxicity from carotenoids; but, beta-carotene supplements in high doses are associated with increased risk of cancer, especially in smokers.

b. Vitamin D: a sterol and a hormone

i. Vitamin D acts as a hormone in our bodies. The active hormone is called calcitriol. We can, theoretically, get enough calcitriol by sun exposure, and shouldn’t need much from our diets. Here’s why:

-Our skin makes an inactive precursor to vitamin D

-Exposure to UV (sun) starts the activation process; the inactive precursor is converted to cholecalciferol, which is released to the blood

-Cholecalciferol gets to the liver, where another conversion occurs… but it is still inactive! Here, in the liver, inactive vitamin D may be stored or released to the blood

-Once in the blood from the liver, the final conversion to calcitriol occurs mostly in the kidneys, but some immune cells can do it too!

ii. Functions

1. Causes cells to insert calcium channels; this includes enterocytes (remember? Cells lining the small intestine). What this means is, vitamin D ensures adequate calcium absorption from the diet. Without enough vitamin D, you will not be able to absorb much of the calcium you eat. Calcium needs to be maintained in the blood because it is vital for clotting, muscle contraction, nerve function, and much more. If you don’t have enough calcium in your blood, you die quickly. Calcium in your blood comes from either your diet or your bones. Vitamin D helps keep your bone mass high because it makes sure that you are getting calcium from your diet, not from your bones.

2. Vitamin D also plays some sort of really important role in the immune system, but nobody knows quite what that role (or more) is. But, it is very likely that adequate vitamin D helps to prevent cancers, some autoimmune diseases such as MS and rheumatoid arthritis, and possibly other chronic diseases.

3. Mild D deficiencies- we now understand that many people in the USA suffer from mild deficiencies of vitamin D. While we get enough to keep our bones healthy, we might not get enough to keep ourselves healthy.

Because of its roles in immune function (which are poorly understood but there is very strong evidence for), low levels of vitamin D are associated with increased sickness, risk of MS and other autoimmune disease, risk of cancer, depression, and generally “not feeling well.” We spend so much time avoiding the sun these days (sometimes, not because we want to but because we’re stuck inside on the computer, writing Lecture Outlines about not being outside, hm….) that many of us are low in vitamin D.

This is one vitamin that it makes sense to supplement, if you are eating a well-balanced diet based on whole foods. (If you’re female, you might be iron deficient too even if you eat red meat… that’s another supplement to consider; and of course, keep up with your doctor about your nutritional status in general).

iii. Recommendations

1. Adults: 5 mcg/day (400 IU)- many researchers want to increase this

2. Daily requirement increases with age; synthesis of the skin precursor gets less efficient.

3. Sun exposure- about 20 minutes without sunscreen per day during the summer- should be enough, and very few foods have adequate amounts. But really high latitude places don’t get enough sun to sustain V-D status throughout the year. That includes Seattle- so most of us need to think about getting enough from food or supplements.

4. Dark-skinned individuals need more sun exposure to get activation of vitamin D.

iv. Sources

1. Sun exposure

2. Seafood

3. Egg yolks

4. Dairy fat (not much D there, but a little)

5. Milk is not a good natural source- it’s only a good source because it is usually fortified.

v. Deficiency

1. Severe: rickets (children) and osteomalacia (adults)

2. Chronic, lower level:

a. Osteoporosis

b. Possibly, increased risk of cancers and autoimmune diseases

vi. Toxicity- this is another that can be pretty toxic but ONLY from supplements

1. UL for adults: 50 mcg (2000 IU); but some researchers want to increase it to 250 mcg (10000 IU)

2. Causes excessive amounts of calcium in blood: muscle dysfunction (including heart), nerve dysfunction, calcification of soft tissues, kidney stones

c. Vitamin E

i. Active: “alpha-tocopherol” (other tocopherols exist, some can be converted to alpha)

ii. Functions

-Antioxidant, works closely with vitamin C, beta-carotene, and selenium (a mineral). Particularly important for protecting the phospholipids (the fatty acid part) of cell membranes and lipoproteins; also protecting DNA (protecting DNA protects you from cancers)

iii. Storage: primarily in adipose and cell membranes; not in the liver

iv. Recommendations:

Adults: 15 mg/day

v. Sources:

1. Fatty plants: nuts, avocadoes, wheat germ

2. Plant oils

3. Many fruits (tomatoes and strawberries are notable sources) and dark green veggies… but be sure to eat with some fat to ensure adequate absorption

4. Animal foods are typically not as important sources

vi. Deficiency

1. Hemolytic anemia: free radical damage to red blood cell membranes… causes them to burst! (hemo= blood, lysis = breaking)

2. Neuromuscular problems, from damage to neuron and muscle cell membranes

vii. Toxicity-

1. UL- 1000 mg

2. Reduced blood clotting, may lead to internal bleeding. This is because high-dose supplements of V-E can interfere with vitamin K’s action in the body (see below).

3. Severe toxicity virtually impossible from food alone

4. Long-term over-supplementation may increase risk of certain cancers

d. Vitamin K

i. Called phylloquinone

ii. Stored in the liver; excess can be excreted more easily than A and D, so less risk of toxicity

iii. Functions:

1. Blood clotting: the formation of a blood clot involves the activation of a series of proteins; the last protein activated forms a mesh around the injured vessel. V-K participates in the activation of many of these proteins.

2. Development & maintenance of bone: critical for the ability of bone protein to mineralize (bind calcium compounds).

iv. Recommendations

1. Men: 120 mcg, women: 90 mcg

2. Some researchers think it should be closer to 400 for optimal bone health

v. Sources

1. Highly abundant in vegetables and many plant oils; especially dark green leafies, cruciferous veggies (broccoli, cauliflower, cabbage etc)… ex, ¼ cup of fresh chopped parsley has 246 mcg

2. Microflora (bacteria) in the large intestine make it, and you get some from them

3. Animal sources not reliable

vi. Deficiency- rare, but can be fatal

1. Reduced clotting; hemorrhaging

2. Increased risk of bone fractures

3. Excess A & D, some antibiotics, can reduce K absorption… why would antibiotics affect K status?

vii. Toxicity- extremely rare; but intake of excessive SYNTHETIC vitamin K, called menadione, can lead to liver damage and hemolytic anemia. No UL is established.

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

c. Flavonoids

d. Isothiocyanates

e. Organosulfur compounds

f. Phenols

g. Phytoestrogens

h. Resveratrol (ex, from red wine)

V. Vitamins on Food Labels

A. Nutrient Facts Panel: The only vitamins that are REQUIRED to be shown on the NFP are vitamin A and vitamin C. They 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 vitamin E reported; but, nuts are a great source of vitamin E and there is definitely some in them. The manufacturer has simply chosen not to report the vitamin E (or most of the other vitamins and minerals the food contains).

B. Ingredients List: Typically, when vitamins are on an ingredients list, they are listed by their TECHNICAL NAMES, so it is important for you to remember those names of the vitamins. Vitamins listed on ingredients lists are NOT whole foods sources; they are essentially just supplements added to the food. Vitamins are usually added to prepared foods for two primary reasons:

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 vitamins on a PopTart label: vitamin A palmitate, niacinamide, pyridoxine hydrochloride, riboflavin, thiamin hydrochloride, folic acid, cobalamin

ii. What vitamins is this food fortified with?

b. To preserve a food using vitamin antioxidants

i. For example, here is a list of some antioxidants added to a food as preservatives: mixed tocopherals, erythorbic acid

ii. What vitamins are used as antioxidant preservatives in this food?

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

However, if only antioxidant vitamins are listed (typically E and C), there is nothing wrong with that; in fact, these are much preferred preservatives than other non-nutritive preservatives, which we will cover later.

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Created by Terri Stilson for NUTR&101