Human Nutrition and Health Study Essay Sample

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1) Nutrients are chemical substances, found in foods, which are utilized in the human body.

2) Minerals, proteins, lipids, carbohydrates, and vitamins are essential nutrients in the human diet. Specifically, amino acids, fatty acids, and water are essential.

3) Non- essential amino acids are synthesized from other simpler nitrogen compounds. For instance, tyrosine, a non- essential amino acid, is synthesized from phenylalanine, an essential amino acid.

4) Protein deficiency malnutrition predominantly causes stunting, wasting, and general developmental disabilities. Other symptoms include: distended abdomen; alternating sections of light and dark hair; & dermatitis.

5) Phenylketonuria (PKU) is an inherited disorder which increases the amount of phenylalanine (an amino acid) in the blood to harmful levels. Effects of untreated PKU may include mental retardation, behavioral issues, seizures, delayed development, movement disorders, a musty odor, lighter skin and hair, and skin disorders such as eczema. Mild cases may not require treatment with a special diet. The main treatment for PKU consists of permanently reducing the amount of protein in the diet. For few people, medicine may help reduce phenylalanine blood levels when used with a PKU diet. Although any brain or nervous system damage that develops is irreversible, problems are less likely to occur if a PKU diet commences by 3 weeks of age.

6) Fatty acids have many variations in molecular structure. One variation is in the length, or how many carbon atoms are in the molecules. Another variation is whether there are double bonds between carbon atoms in the hydrocarbon chain or not. If there is a double bond, the fatty acid is unsaturated because the number of hydrogen atoms it can bond to is reduced. If there is solely one double bond in the hydrocarbon chain, the chain is monounsaturated; whereas, if there are more than one double bonds, the chain is considered polyunsaturated. Another variation in molecular structure which occurs with double bonds is the cis or trans orientation of the hydrogens attached to the double bonded carbon atoms. In the cis structure, both hydrogen atoms are bonded on the same side. In the trans structure, the hydrogen atoms are bonded on opposite sides. Refer to the image below for further clarification:

Image I: Cis vs. Trans

7) Dietary trans fatty acids (hydrogenated fat) increase LDL cholesterol levels, though they have little effect or decrease HDL cholesterol levels. Thus, there is a greater difference in the LDL cholesterol/HDL cholesterol ratio (which is unfavourable). Lipoprotein (a) levels incline with increased trans fatty acid consumption. Lp(a) is a putative risk factor for atherosclerotic diseases such as coronary heart disease (CHD) and stroke. Trans- fat also causes inflammation, which is thought to occur through damage to the cells lining of blood vessels. In autopsies post- CHD caused deaths, the majority of fat in arterial plaque is reported to be trans- fat. Cis-monosaturated fatty acids have been reported to decrease CHD. However, other factors related to cis-monosaturated fatty acids may vary (such as genetic factors) which may explain differences in the rate of CHD. Excessive consumption of saturated fatty acids has also been correlated with increased cardiovascular disease and CHD mortality. Omega-3 fatty acid deficiency is predicted to impair brain and eye development (because much of the tissues of these organs are composed of long- chain fatty acid, which are synthesized by omgea-3 fatty acids, among others).

8) Minerals are chemical elements (except C, H, N, and O which are present in common organic compounds), generally in ionic form, whereas vitamins are organic compounds.

9) One method of determining the recommended daily intake of vitamin C (ascorbic acid), occurred during WWII in England and the United States, in which volunteers ingested varying levels of vitamin C for an nearly ten months. Volunteers who consumed 70mg of vitamin C for six weeks and were deprived of the vitamin for the remainder of the trial developed survey, failed to heal when wounded, bled from hair follicles and gums, and multiple subjects developed cardiovascular problems. Trial subjects who ingested between 10 and 70mg remained healthy. Another procedure utilized to determine essential ascorbic acid intake was preformed on guinea pigs, as they, similarly to humans, cannot synthesize this vitamin. Concentrations in blood plasma and urine were monitored and collagen in skin and bone were evaluated.

10) Typically, the recommended adult dosage of ascorbic acid it 30- 60mg per day. This level is higher than necessary in order to maintain a safety margin. This is the recommended dosage in order to prevent scurvy.

11) There are few dietary sources of vitamin D. Oily fishes including herring, mackerel, sardines, and tuna are rich sources. Eggs and liver also contain low levels of vitamin D. Margarine and milk are artificially fortified with vitamin D.

12) Fibre is important in a balanced diet for three predominant reasons:

a. It aids your digestive system in processing food and absorbing nutrients.

b. It decreases blood cholesterol.

c. It maintains blood sugar levels and increases the bulk in the stomach, which in turn controls appetite.

d. It may reduce risk of diseases of the large intestine including appendicitis, cancer, and haemorrhoids.

e. It may decelerate the rate of sugar absorption, thereby preventing or treating diabetes.

13) 100g of carbohydrate or protein contains approximately 400 calories of energy, whilst 100g of fat generally contains 900 calories of energy.

Table I: Nutritional Energy

Nutrient

Energy (kJ/100g)

Carbohydrate

1760

Protein

1720

Fat

4000

14) In cases of anorexia nervosa, the individual does not consume enough carbohydrates or fats for use in cellular respiration. Therefore, protein is broken down. Consequently, muscles lose mass and become weaker; the individual experiences fatigue; hair becomes more brittle; the epidermis becomes dry; bruises are formed easily; there is a growth of fine hair on the body, blood pressure declines; circulation becomes poor and the heart rate decelerates; and in females, menstrual cycles often haul, yielding the individual infertile. Ultimately, chronic and extreme anorexia nervosa causes death.

15) Table II: Breast milk vs. Artificial milk

Breast milk

Artificial milk

Carbohydrate

Lactose

Lactose or glucose polymers

Protein source

65% human whey proteins; 35% casein

18% bovine whey; 82% bovine casein or soya proteins

Fatty acids

Human butterfat

Palm, coconut, soy, or safflower oils

Antibodies

Antibodies present in the colostrum

No antibodies present

16) Advantages of breast feeding:

a. Promotes bonding between mother and infant

b. Serves as a natural birth- control method, reducing the probability of conception while the mother is lactating

c. Aids the mother in post- pregnancy weight loss

d. Avoids the allergies to proteins in cows’ milk or soya that can develop when infants receive artificial milk

e. Breast milk is naturally sterile, and thus, is safer in areas where it is not feasible to attain sterile water for artificial milk.

f. Provides newborn infants with essential antibodies.

17) There is an absolute connection between cardiovascular problems (such as atherosclerosis, hypertension, and CHD) and blood lipid concentrations. Consumption of lipids in large quantities carries a significant risk of obesity and CHD (refer to question 7). The type of fat is a determining factor. Trans fats are the most associated with obesity and CHD. Because trans- fatty acids have been identified as factors which increase LDL concentrations and decrease HDL concentrations, high dietary trans- fat levels are attributed to obesity and CHD.

18) Food miles are a measure of how far a food item has been transported from where it was produced to where it is consumed. It is necessary to reduce food miles as they cause air pollution, traffic congestion, release greenhouse gases, and increased use of energy and fertilizer for year long production. A reduction in food miles would also instigate an increase in local market and economy.

19) Malnutrition refers to a medical condition caused by an insufficient diet. Specifically, the condition is generally caused by inadequate consumption, absorption, or retention of nutrients. It can also encompass the medical consequences of consuming an excessive amount of certain nutrients.

Resources:

http://children.webmd.com/tc/phenylketonuria-pku-treatment-overview

http://www.medicinenet.com/phenylketonuria/index.htm

http://www.madsci.org/posts/archives/2006-02/1139385004.Bc.r.html

http://www.ncbi.nlm.nih.gov/pubmed/10860195

http://en.wikipedia.org/wiki/Lipoprotein(a)

http://www.jlr.org/cgi/reprint/33/10/1493

http://en.wikipedia.org/wiki/Fatty_acid#Unsaturated_fatty_acids

http://en.wikipedia.org/wiki/Saturated_fat#Dietary_recommendations

http://www.netdoctor.co.uk/focus/nutrition/facts/lifestylemanagement/fibre.htm

http://www.merck.com/mmhe/sec12/ch152/ch152b.html

http://en.wikipedia.org/wiki/Malnutrition

http://membership.acs.org/C/carb/Glc.jpg

http://staff.jccc.net/PDECELL/biochemistry/phospolips1.gif

http://www.biosci.ohio-state.edu/~prg/protein1.gif

http://content.answers.com/main/content/wp/en-commons/thumb/2/29/250px-Periodic_table_of_the_chemical_elements_(1-118)Dietary_minerals.PNG

http://www.3dchem.com/imagesofmolecules/vitaminBc.jpg

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