BIOL 135: Biology of Human Nutrition

What is

Nutrition?

Nutrition is the process of taking in food and using it for growth, metabolism, and repair.

Nutritional Stages:IngestionDigestion AbsorptionTransport

AssimilationExcretion

Nutrients are substances that we must have in our diets in order for our cells to function properly.

Carbohydrates Vitamins

LipidsMinerals

Proteins Water

How many categories of nutrients are there in Human Nutrition? ___

Energy Yielding Vs Non-Energy Yielding Nutrients

6

Advertising Availability

Beliefs and ValuesBody Weight

Comfort Convenience

Economy Ethnicity

Geographical Location Habit

Nutritional Value Personal Preference

Positive Associations Social Influences

Traditional Customs

What influences the Nutritional Choices we make?

Describing the Nutrients

There are Several ways to Classify Nutrients.– Essential or Non-Essential– Organic or Inorganic– Macronutrient or Micronutrient– Energy Yielding or Not

Classifying NutrientsEssential Nutrients* – nutrients the body either cannot make or cannot make enough of to meet its needs *Omission from diet leads to a decline in a

biological function; return restores function

Non-Essential Nutrients – body can make from other nutrients ingested

Examples: 3 Fatty Acids; 9 Amino Acids, All Vitamins and Minerals

Examples: All Carbohydrates! 11 Amino Acids, Cholesterol…

Composition of Nutrients • Organic Nutrients - contain Chains of Carbon

• Carbohydrates• Lipids• Proteins• Vitamins

• Inorganic Nutrients - do not contain Carbon Chains• Minerals• Water

Quantity Needed• Macronutrients: need in relatively large amounts

– Carbohydrates – Lipids – Proteins

• Micronutrients: need in relatively small amounts– All other Nutrients

Energy Yielding Nutrients• Energy-Yielding Nutrients (3):

– Carbohydrates = 4 kcal/g– Lipids = 9 kcal/g– Proteins = 4 kcal/g

• Where does the energy come from?

+ Energy-Yielding Non-Nutriente.g., Alcohol = 7 kcal/g

Non-Nutrient, as it interferes with growth, maintenance and repair of the body - Alcohol’s metabolites are harmful.

Energy DensityFor

Critical

Analysis

Food Choices• Small Group Exercise: Answer Questions:

Make a brief list of the Factors that impact your food choices most days. (top 3)

13

Food Facts/Myths• Individual Exercise: Survey Questions: Honestly answer of Food Fact or Myth Survey!

Food Choices

1. Personal Tastes2. Habit3. Ethnic Heritage4. Tradition5. Social Interactions or

Pressure6. Availability7. Convenience

8. Economy $9. Positive or Negative

Associations10. Emotional Comfort11. Values - Religious, political…

12. Health Concerns13. Nutritional Value

= my additional suggestions Connecting Nutrition to Disease.

Top 10 Killers in the USA

Carbohydrates• Composed mostly of C, H, and O: C(H2O)n

• Major source of fuel for body 4 kcal/g energy

• Glucose - major molecule in the body uses

Glucose SucroseFructose

These are all Simple Sugars

+ =

Carbohydrates

• Can be in form of simple monosaccharides, like glucose or sucrose, or complex polysaccharides.

• Some complex carbohydrates cannot be broken down by human digestion - dietary fiber.

Lipids• Mostly C and H, few O• Yield more energy 9 kcal/g than carbs or proteins

• Insoluble in water, i.e. non-polar

• Some Amphiphilic (Phospholipids)

• “Fats” and “Oils” have a basic structure of:glycerol plus fatty acids attached to each Carbon to give a triglyceride

• Saturated fats - solid at room temperature

• Unsaturated oils - liquid at room temperature

Triglycerides are major form of fat in foods

Classification of Fatty Acids

Saturated Fats and Trans Fats are not the same

Formation of Triglycerides

Note the different configuration of the ‘tails’

Ancel Keys cover of Time Magazine in 1961. He claimed that saturated fats in the diet clogged arteries and caused heart disease.

Time Magazine cover story in 2014. Scientists were wrong about saturated fats. They don’t cause heart disease after all.

The Famous Seven Countries study by Dr. Ancel Keys (1961)Survey 13,000 men, aged 40-59 y from seven countries, detailed food consumption patterns to find associations between diet and heart disease.Of the 300 men from Crete study only 31 were actually surveyed about eating habits.

Dataset from each of the 7countries, somewhere between 25 and 50 men. Plus Keys took one of his food-recall surveys in Greece during Lent, when religious Greeks abstain from animal foods.

Sample size ridiculously small if the goal is to accurately compare diets and heart disease in seven countries. This is also assuming the dietary records were accurate.

Also, the original 7-day records were no longer available.

Reconstructed diets, fruit & veg intake, used data of food availability during a 4-year period.

Also intentionally left out countries with high fat consumption but low heart disease; and those with low fat consumption but high rate of heart disease.

And from this amazingly rigorous and scientific study, he concluded that high-fat diets cause heart attacks and low-fat diets prevent them.

This is one of the most-cited studies in all of medical science - one of the pillars of the Diet-Heart hypothesis, convincing USDA, the AHA, doctors, nutritionists, media health writers… that saturated fat clogs our arteries and kills us, so we all need to be on low-fat diets – even kids.

ProteinsMade with amino acids – the building blocks!Contains the atom C, O, H, and N

Many uses in the body (structure, protection, movement, communication, transport)

ProteinsProvides 4 kcal/g energy (not often used for fuel)

Most people eat more protein than they use!

Amino Acids

5 Brain Nutrients Found Only in Meat, Fish and Eggs (NOT Plants)

1. Vitamin B12 – Deficiency leads to anemia, impaired brain function, symptoms of mental disorders and a smaller brain.

2. Creatine – For muscle actions and neurons. Deficiency adversely affects muscle and brain function.

3. Vitamin D3 - Deficiency: linked to depression, impaired immune system, cardiovascular disease and cancer, autoimmune disease, multiple sclerosis and cognitive impairment.

4. Carnosine - A potent antioxidant, inhibits glycation from high blood sugars Levels are significantly lower in patients with Parkinson’s and Alzheimer’s

5. Docosahexaenoic Acid (DHA) - essential Omega-3 fatty acid - if we don’t eat them, we get sick.

VitaminsFunction: to allow and assist chemical reactions to occur in body!• Help release energy trapped in organic molecules (carbohydrates, lipids, and proteins)

• Vitamins do not provide usable energy for bodyApprox 13 vitamins divided into 2 groups:

Fat soluble - A, D, E, K

Water soluble - C and B vitamins

Criteria for Classifying Vitamins

Vitamins are classified based on solubility.– Four fat-soluble:

• Vitamin A• Vitamin D• Vitamin E• Vitamin K

– Nine water-soluble:• B vitamin complex• Vitamin C

The Chemical Structure of Vitamin D

Epidermis of Skin

Dermis of Skin

7-dehydrocholesterol

UV Light+

Cholecalciferol (Vit D3)

Your cells only make Vitamin D if UV stimulation is adequate (~20 min/day)

“Calcidiol” 25-Hydroxycholecalciferol

(25-Hydroxy Vit D3)Allow your healthy Liver to process Vit D3 into Calcidiol.

“Calcitriol”1,25-Hydroxycholecalciferol

(1,25-Hydroxy Vit D3)

ACTIVE FORM

Allow your healthy Kidneys to process Calcidiol into the most active form,

Calcitriol.

UV Light

UV Light

The story of Vitamin D

The Absorption of Vitamin B12

MineralsInorganic compounds that exist as groups of one or more of the same atoms

Include: Na+, K+, Mg2+, Ca2+, Cl-, Ca10(PO4)OH2

Critical for: nervous system function, maintaining electrolyte levels, water balance, and skeletal and endocrine systems.

Daily Needs for Sodium

Question: What might be inaccurate or wrong about how this is presented?

Things have changedThe Soil is depleted of Essential Minerals

Therefore the Food is Depleted too

Iron Absorption and TransportAbsorption-transport mechanism of iron tightlycontrolled to prevent toxicity.

Metabolic Functions of Iron• Participates in oxidation-reduction reactions• Major component of hemoglobin and myoglobin

– Transports oxygen and carbon dioxide

Water

Water

• Acts as Solvent and Lubricant in body

• Used to Transport Nutrients and Wastes

• Medium for Body Temperature Regulation

• Participates in Chemical Processes

Water • Makes up about 70% of total body weight.• We need water – can survive for only a few

days without it.• It is found in:

– Intracellular fluid– Extracellular fluid

Intracellular and Extracellular Fluid Compartments

Properties of Water

1) Solvency - universal solvent.

2) Cohesion - surface tension and adhesion.

3) Thermostability - high heat capacity. Define calorie. Also high heat of vaporization.

4) Reactivity - Water participates in chemical reactions e.g. Hydrolysis and Dehydration Synthesis

Pure and Clean

Water

Pure and Clean water

is Important

Do You know what ‘s

in You’re Tap water?

Drugs in Your Drinking Water – deposited via two routes.

1)Drugs taken or given to livestock, can remain active and are not absorbed, so are deposited into sewage treatment, not always looking for or removing, prescription drugs. 2)Flushing unused prescription drugs down the toilet or tossing into landfills can end up back in environment.

Rocket Fuel - Perchlorate (fireworks, road flares, rocket fuel), found water supplies of 36 states. Interrupt thyroid hormones, needed for pre- and postnatal development. Hypothyroidism.

Heavy Metals (inorganic chemical elements with high density): mercury, arsenic, chromium, cadmium, nickel and lead, can accumulate in water supplies through human activity (industrial and consumer waste). Also lead and copper water pipes can leach into the passing water.

Chlorine and FluorideToxic chemicals are deliberately added to your water! Chlorine, toxic enough to kill bacteria (safe to drink?). Can increase child’s risk of heart problems, cleft palate or major brain defects.

Cancer-causing agents when chlorine come in contact with organic materials already in water, e.g., trihalomethanes. Note: washing dishes with antibacterial dish soaps in tap water isn't safe for you either.

Fluoride as toxic as chlorine, widely promoted as healthy in reality, fluoride is a poison that harms health, used in rat poison, accumulates in bones, causing brittle fluorosis; in pineal gland disrupts melatonin (sleep, puberty onset). Also increase aluminum uptake in brain and lead in blood.

Tap Water Gives You CancerStudy of ~ 8,000 people: tap water can increase the risk of bladder cancer. Chlorine and antibacterial soaps make more carcinogens in water.

Bottled Water is Not the AnswerExtreme toll on environment and just as unsafe as tap water, plus other toxins leaching form the plastic bottles.

Monitor Water Intake to Avoid Over-hydration and Dehydration

Evaluate urine color to assess hydration

© 2016 Pearson Education, Inc.

Daily Beverage Recommendations

For

Critical

Analysis

What is Wellness?

The Wellness Wheel

1. Physical Wellness - ability to maintain a healthy quality of life that allows us to get through our daily activities without undue fatigue or physical stress.

2. Emotional Wellness - to understand ourselves and cope with the challenges life can bring. The ability to acknowledge and share feelings of anger, fear, sadness or stress; hope, love, joy and happiness in a productive manner.

3. Mental Wellness - a state of well-being in which the individual realizes his or her own abilities, and is able to create and maintain a stimulating and alert mental attitude.

4. Social Wellness - ability to relate and connect with other people in our world. Our ability to establish and maintain positive relationships with family, friends and co-workers.

5. Occupational Wellness – deriving personal fulfillment from our jobs, our chosen career or the way we spend our time.

6. Intellectual Wellness - ability to open our minds to new ideas and experiences and applying to personal decisions, group interaction and community betterment. The desire to learn new concepts, improve skills and seek challenges in pursuit of lifelong learning - stimulating the mind and mental capacity.

7. Spiritual Wellness - ability to establish peace and harmony in our lives and develop congruency between ourvalues and actions to realize a common purpose that binds creation.

8. Environmental Wellness - ability to recognize responsibility for the quality air, water and land around us and to make a positive impact on the quality of our environment, be it our homes, our communities or our planet.

DNA

Proteins

RNA

“Central Dogma”Agouti Mice Experiment

Normal Agouti

“traits”

Leptin - hormone released by fat cells after eating.

When leptin levels rise, alpha melanocyte stimulating hormone (α-MSH) rises, increasing metabolic rate, triggering satiety.

α-MSH plays a role in feeding behavior, energy homeostasis, and sexual activity. Also stimulates melanogenesis, for pigmentation of hair and skin.

A naturally occurring genetic mutation blocks the function of α-MSH. Phenotypic changes result, e.g. the Agouti Mouse!

Agouti mice: Have yellow coats, display obesity, diabetes and cardiovascular disease, similar to animals missing leptin.

Experiment

Agouti MiceParents

Dietary Supplement

No Dietary Supplement

folic acid, B12, choline, betaine

FIG. 4.Avy PS1A methylation as a

function of tissue type and animal age. (A) Average percent methylation of seven CpG sites

in the Avy PS1A in tail (T), liver (L), kidney (K), and brain (B)

samples from five Avy/a animals representing the five coat color

classes shown in Fig. 2A. Avy methylation in the tail correlates highly with that in other tissues

(r2 > 0.98 for all comparisons). (B) Average percent methylation

of Avy PS1A in day 100 liver versus that in day 21 tail tip

DNA. Percent methylation in day 21 tail predicts that in day 100

liver (r2 = 0.95). Open triangles, unsupplemented offspring; solid

triangles, supplemented offspring. Neither group

departed significantly from the line of identity (shown). Hence,

Avy PS1A methylation is maintained with high fidelity into

adulthood.Mol Cell Biol. 2003 August;

23(15): 5293–5300. doi: 10.1128/MCB.23.15.5293-

5300.2003.

“Epigenetics”

Regulatory Proteins

Environment

DNA

RNA

Proteins

Proof you can change your genetics daily (hourly) by the foods you eat and …

Exercise…Thoughts…Emotions…

Nutrient Composition of Diets and the Human Body

• Total daily intake of carbohydrate and fat and protein is about 500g

• Mineral intake is around 20g

• Vitamin totals less than 300mg

A Brief History of Human Nutrition

400 B.C. - Hippocrates, "Father of Medicine", said "Let thy food be thy medicine and thy medicine be thy food". He also said “A wise man should consider that health is the greatest of human blessings”.

400 B.C. - Foods as cosmetics or medicines in the treatment of wounds. Biblical references to food and health, e.g., treating of eye disease by squeezing liver juice onto eye. Vitamin A deficiency, stored amounts in the liver.

1500’s - Scientist and artist Leonardo Da Vinci compared metabolism in body to the burning of a candle.

1674 - British physician Sydenham showed iron filings in wine can treat anemia.

1747 - British Navy Dr. James Lind 1st experiment in nutrition giving sailor limes (vs. sea water and vinegar) to combat scurvy – not known at the time as a Vitamin C deficiency (Vitamin C discovered in 1930’s).

1770 - Antoine Lavoisier ‘Father of Nutrition and Chemistry’ demonstrated the process of food metabolism and where animal heat comes from. Equation of food and oxygen in body -> resulting in giving off of heat and water.

Early 1800’s - Discovered that foods composed primarily of 4 elements: Carbon, Nitrogen, Hydrogen and Oxygen, and methods were developed for determining the amounts of these elements.

1816 - German physician Magendie showed that dogs fed only on carbohydrates rapidly lost body weight and died in a few weeks. : (

Food + O2 H2O and Heat

1840 - German Justus Liebig, early pioneer in plant growth studies, first show chemical makeup of carbohydrates, fats and proteins. Carbohydrates – made of sugars, fats - fatty acids, and proteins - amino acids.

By 1850 - Six minerals had been identified that were required for survival: Ca, Na, K, P, Cl, and Fe.

1890’s - Rubner and Atwater established the kilocalorie (kcal) as the energy content contained in proteins, fats, and carbohydrates.

1897 - Dutchman Christiaan Eijkman observed that chickens and people who ate native diet of white rice developed Beriberi, causing heart problems and paralysis. When he fed chickens unprocessed brown rice (outer bran intact), no disease developed; also fed brown rice to and cured his patients; connected food to curing disease. Note: The outer rice bran contains vitamin B1, (AKA thiamine).

1912 - E.V. McCollum, agriculturalist, decided to work with rats rather than large farm animals. He discovered the first fat soluble vitamin, Vitamin A; found rats fed butter were healthier than those fed lard (more Vitamin A in butter).

1912 - Dr. Casmir Funk first to coin term ‘vitamins’ as vital factors in diet. He recorded these unidentified substances in food, which could prevent the diseases of scurvy, beriberi and pellagra (caused by deficiency of niacin, vitamin B3). Vitamin derived from vital and amine (derived from ammonia).

1930’s - William Rose discovered the essential amino acids, the building blocks of protein. They are:

1940’s - The water soluble B and C vitamins were identified.

Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine.

1950’s to Present - The important roles of essential nutrients as part of bodily processes better understood; e.g., the role of vitamins and minerals as components of enzymes and hormones working in body.

1968 - Linus Pauling, Nobel Prize winner in chemistry, created the term Orthomolecular Nutrition, meaning, "pertaining to the right molecule". Pauling believed by giving the body the right molecules in the right concentration (optimum nutrition), nutrients could be used by people to achieve better health and prolong life.

1970's and 1980's - Studies by Pauling and colleagues suggested that very large doses of vitamin C given intravenously could be helpful in increasing the survival time and improving the quality of life of terminal cancer patients.

1994 - 2000: The Dietary and Supplement Health and Education Act approved by Congress 1994, sets forth what can and cannot be said about nutritional supplements without prior FDA review, e.g. “this products is not intended to diagnose, cure or prevent any disease”. Also mandates that their health claims have not been evaluated by the Food & Drug Administration (FDA). 2000 (Jan) - FDA ‘allows’ supplement makers to state their products can improve the structure or function of the body or improve common, minor symptoms, include: ‘maintains a healthy heart’, ‘helps you relax’, ‘relieves symptoms of PMS’, ‘strengthens joint structure’, etc.

2003 - FDA announces it will require food labels to include trans fat content. Labeling went into effect in 2006.

2015? – Voting public requires labeling of Genetically Modified Foods!