Nutrition

Vitamins, Minerals & Water

Objectives
By the end of this lecture you should be able: To Know the etiology, epidemiology, food sources, maj. Functions, RDA of vit.& minerals, To memorize the risk groups, vit.& minerals deficiency s&s, prevention &control of vit. &minerals deficiencies that cause a community health problems, factors that increase& decrease Cal., Fe& I absorption, water daily allowance for adult.

"Vitamins"

They are organic compounds that are essential in small amounts for control of metabolic processes & cannot be synthesized by the body. Many act as coenzymes or as part of enzymes responsible for promoting essential chemical reactions.

*Vit. A & niacin can be formed in the body if their precursors are supplied. *Vit. K, bioten, folacin & B12 are produced by micro-organisms in intestinal tract. *Vit. D is synthesized from a cholesterol precursor in skin on exposure to UV sunlight (within 15-30min. after sunshine= sun shine vit.). Classification: Vitamin are classified into 2 groups on the bases of solubility:


1-Fat- sol. vit.; vit. A,D,E,&K: They are absorbed with other lipids ,stored in various tissues (they are not normally excreted in the urine). 2-Water sol. vit.; vit B-complex& Vit.C. They are components of essential enz. System & involved in the reactions supporting energy metabolism. They are not normally stored in the body but excreted in the urine, so daily supply is desirable to avoid depletion.

Vit. A Deficiency: 1- Early; *increase rate of infection (respiratory &GI, UT epith. t.) *poor growth. *hard dry skin (goose flesh). *impaired immunity & risk of death.2- Chief manifestations –ocular : *night blindness=reduce ability to see in dim light (preventable). *Bitot’s spots=pearly foamy like triangular shape (treatable). *xerophthalmia (dry eye). *corneal ulceration (permanent damage)& blindness.


Etiology of VAD: 1- Primary deficiency: dietary inadequacy (V.A & protein). 2- Secondary def.: depletion due to pregnancy & lactation, PEM, liver diseases, chronic fat mal absorption. *Bad feeding practices, & early weaning. *Contaminated environment, poor sanitation, poor living conditions, personal hygiene, usually participate infection. *Overcrowding house, poverty, low educational status.


Epidemiology of VAD: Increase morbidity & mortality in affected <5y. Children because of infections. It is a major cause of death in developing countries. Global estimation of the clinically (severe) affected <5y children is 2.8 million, & sub clinically affected (mild –moderate) is 251 million.

Vitamin A deficiency: a public health problem

Vitamin A deficiency (VAD) is a major nutritional concern in poor societies. Its presence as a public health problem is assessed by measuring the prevalence of deficiency in a population (biochemical and clinical) indicators of status. Deficiency of sufficient duration or severity can lead to disorders.

Prevention of VAD:

In infants & Children: 1- Promotion of exclusive breast feeding for 1st 6m. of life, for bottle fed baby use fortified formulas. 2-National supplementation program in Iraq implemented in 1995; prophylactic doses of V.A; For infants:100,000IU with measles vaccine at 9m. of life. 2nd dose 200,000IU with 1st booster dose of DPT vaccine at 18 m., another dose 200,000IU during 1st primary school year.

3- for lactating mothers. Vit.A supplementation 200,000IU during purperium (40 days post delivery) 4-Childern with measles or PEM; 100,000IU for <1y. Infant , &200,000IU for older children. 5- Complete immunization schedule for <5y. Children. 6-Improve sanitation & food hygiene. 7-Nutritional education. 8-Increase awareness of physician &health personnel.

*VitaminD (calciferol): Food sources: liver, egg yolk, fish, dairy products(milk gp.) Maj. Function: absorption of Ca.&Po4, mineral homeostasis, maintenance of bone & teeth. Risk group: prolong breast fed child, elderly, dark skin, little sun exposure. Vit. Deficiency: rickets in children, osteomalacia in adults.

Inorganic Nutrients

Minerals *Macro minerals *Micro minerals Water

"Minerals"

They are inorganic substances.They represent about 4-5% of body weight & about 50% of them are calcium & 25% are phosphorous, other minerals constituents the remaining 25% . When the RDA of minerals is ≥100mg/day called macro minerals eg. Ca., Po4 , Mg, Na, Cl, K, S---, while if the requirements of the minerals <100mg/day called micro minerals =trace elements (Fe, Zn, Cu, I, Mn, F, molybdenum, cobalt, selenium, chromium, nickel--).



They are dissolved as ions in body fluids *which regulate the activity of many enzymes,*maintains acid-base balance & osmotic pressure,*facilitate the transfer of essential compounds though cell membrane & maintains nerve & muscular irritability. *Some minerals involve indirectly in the growth process.

Characteristics of Minerals:

• Some need a carrier.• Large consumption of one mineral may suppress the absorption of another mineral• Mineral binders (decrease cal. absorption = indigestible) :– Phytic acid – found in the grains and legumes.– Oxalic acid – found in green leafy vegetables, strawberries.

"Minerals in Human Nutrition"

I-Macro-minerals: *Calcium: Location in the body : 99% in bone & teeth& 1% in body fluid. Biological function: bone mineralization, CNS functioning (nerve impulse), blood clotting, B.P. regulation. When s. cal. Levels get too low cal. Homeostasis: 1-Bone release cal. (controlled by PTH, calcifirol= active vit,D H. 2-Intestine absorb more cal. 3-Kidneys retain more cal.


RDA for adult : 800mg for male 1200mg for female &old age. Food sources: milk &dairy prod., sardines, ice-cream, molasses, sesame oil.

*(spinach, broccoli, cabbage, beans, contain oxalic acid). *Tea & coffee contain oxalic acid+ tannins decrease cal. absorption

RDA= Recommended Dietary Allowances.

Calcium Deficiency : Osteoporosis in old age (abnormality in bone structure), Osteomalacia (=adult rickets) (+V.D def.) Tetany (m. spasm & leg cramps), irritability of nerve fibers or due to decrease Ca:Po4 ratio, Hypertension (abnormal calcium metabolism)

Healthy vs. osteoporotic trabecular bone

Osteoporosis –Prevention • Adequate dietary calcium intake.• Increase physical activity& adequate body weight.• Do not smoke and limit alcohol intake.

Factors favoring cal. Absorption: *Body needs for higher amounts( pregnancy& lactation). *Milk lactose. *Sufficient vit. D. *Acidity of digestive tract: cal. Sol. In acidic medium. Factors decrease cal. Absorption: *Binders; phytic acid &oxalic acid. *Dietary fat: form insol. Soap with cal. *Dietary fibers& laxatives. *Excessive phosphorus & magnesium intake. *Aging, sedentary life style, drugs.

II-Micro-minerals:

*Iron: Location in the body &biological function: 70% in Hb & myoglobin, 26% stored in liver, spleen,& bone. RDA for adult: 10mg for male,15mg for female. Food sources: heme iron; liver& meat easily absorbed than non heme iron; egg yolk, legumes, whole or enriched grains, dark green vegetable, dried fruits (plant sources). Absorption incr. by V.C. Factors decrease absorption of plant sources of iron : -Binders (phytate & oxalate). -Tannins; in tea & coffee. -Continuous use of antacid.

Iron deficiency: Iron def. an.=IDA is a public health problem, esp. in females during teenage & reproductive years, in infants & pre-school children (are risk groups), in case of unusual blood loss, parasites & mal absorption. Anemia (low Hb level) is last effect of iron deficiency state( no liver store). Prevention & Control: 1.Supplementation: iron tab. For target groups; a. Preg. Women during 2nd &3rd trimester as prophylactic dose. **If the prevalence of IDA<20% give 1tab./d (each tab. Contain 60mg Fe)

**If the prevalence of IDA≥20% give 2tab./d***Iraqi national program 2-3 tab./d as a prophylactic dose, even iron status is normal. b. Lactating women; for the 1st 6 weeks after delivery 2-3tab./d c. LBW & premature infant ;drops 2mg/kg/d from 3-12m as prophylactic dose. 2- Food fortification (flour fortification).3-Dietary habits modification.4-Control of infection.5-General hygienic measures.6-Studing the IDA causes to direct the prevention& control measures accordingly.

Food sources : iodized table salt, sea foods, salt water fish > fresh water fish 10-100x /kg, water, milk, eggs & vegetables in non-goiterous region (according to iodine amount in the soil). Iodine absorption decreased by goitrogens ; substances in root veg.; cabbage, cauliflower,-- which suppress the action of thyroid gland. Iodine deficiency =Iodine def. disorders IDD ( endemic or = simple goiter) is a community health problem esp. in adolescent, preg. or lactating females (risk groups).

Epidemiology:It constitute a global problem& is one of the major health issues today. Over 14% of the word’s population are estimated to live in iodine deficient areas &. It is more directly related to socioeconomic status.It is a geographical disease (lack of iodine in the environment).

Etiology of IDD:

Deficient intake of iodine in water or diet (mountain areas). Increase requirement in; developing fetus, new born, young children, adolescent women, pregnant & lactating women. Goitrogenes: natural substances (in cabbage, soybeans, cauliflower, beetroot--) which block iodine absorption & utilization, inactivated by cooking. Individual susceptibility.

Prevention of IDD:

1- Iodization of table salt; 2- Iodized oil given by single injection which provides protection for 2-3y. 3- Iodization of water supply: applied for remote villages. 4-Improving of socioeconomic status; consume fish & variable foods, decrease consumption of goiterogenes. 5- Good medical services & health care for early diagnosis & treatment.


Micronutrient deficiency=Hidden hunger:
Trace elements deficiency is present usually in developing countries, S.t. associated with PEM, usually sub clinical& delayed clinical symptoms to moderate & severe cases. It includes; iron deficiency anemia (IDA), iodine deficiency disorders (IDD), vit. A deficiency (VAD)

"Water"

It is the largest single component of the body wt. (55-65%)in adult, but it varies among individuals, depending on the proportion of the muscles to adipose tissues. Total body water decrease significantly with the age, & is higher in athletes than non athletes.


Notes: *Loss of 20% of body water death. *Loss of 10% of body water severe disorders. *In moderate weather adult can live up to 10 days without water while child can live up to 5 days, (he can survives for several weeks without food).

Water balance:

The water requirement regulated by antidiuretic H. (ADH). Foods that inhibit Antidiuretic Hormone function: • Alcohol • Caffeinated beverages. The amount of daily water intake= amount of water lose. In healthy individuals, water intake is controlled by thirst.

Water allowance based on recommended caloric intake is 1ml/Kcal for adults & 1.5ml/Kcal for infants (under ordinary circumstances) or 35ml/kg of usual body weight for adult, 50-60ml/kg for children ,150ml/kg for infants. Thirst is usually an adequate guide for water intake except in infants, in sick & s.t. in elderly (decrease thirst sensation) . Any one sick enough to be hospitalized (regardless the diagnosis) is at risk of water & electrolyte imbalance. In lactating mother the need for water is incr.( for milk production) so additional 600-700ml/day water.