REVIEW ON BALANCED DIET

SAYAN CHAKRABORTY
BENGAL SCHOOL OF TECHNOLOGY( A COLLEGE OF PHARMACY)
B. PHARM ,4th YEAR

I. Introduction: -(1)

         A balanced diet is also known as prudent diet   . It is defined as a diet which comprises different types of foods, possessing nutrients like carbohydrates ,  proteins  ,fats  , vitamins, minerals  fibres and water  in a proportion to meet the requirements of  the body.

A balanced diet   invariably supplies a little more of each nutrient than the minimum requirements to withstand the short duration of leanness and keep the body in a state of good health .

          The basic composition of balanced diet is highly variable, as it differs from country to country, depending on the availability of foods. Social and cultural habits, besides the economic status, age, sex, and physical activity of the individual largely influence the intake of diet.

           The Indian balanced diet is composed of cereals (rice  , wheat,  jowar  )  pulses ,  vegetables , roots, tubers, fruits, milk and its product ,fats and oils , sugar groundnuts . Meat,  fish, and eggs are present in non vegetarian diets.

·         IN CASE OF VEGETARIAN ADDITIONAL MILK AND PULSES ARE RECOMMENDED.

                  It has been observed that in certain developed countries excessive intake of nutrients is consumed so it is recommended to reduce the total calorie intake by referring a daily intake of less than 30 % fat against the present 40 to 50% towards calories.

                   Although much remains to be learned about the role of specific nutrients in decreasing the risk of chronic disease, a large body of evidence supports the utility of healthy dietary patterns that emphasize whole-grain foods, legumes, vegetables, and fruits, and that limit refined starches, red meat, full-fat dairy products, and foods and beverages high in added sugars. Such diets have been associated with decreased risk of a variety of chronic diseases.

          Diet, of course, is just one approach to preventing illness. Limiting caloric intake to maintain a healthy weight, exercising regularly, and not smoking are three other essential strategies. Compelling data from the Nurses’ Health Study show that women who followed a healthy lifestyle pattern that includes these four strategies were 80% less likely to develop cardiovascular disease over a 14-year period compared to all other women in the study.(3)A companion study, the Health Professionals Follow-up Study, showed that similar healthy choices were beneficial in men, even among those who were taking medications to lower blood pressure or cholesterol.(4)

II. Literature review

Mellen PB  et al.,[2008](14) ( Whole grain intake and cardiovascular disease ) evaluated that by taking whole grains which contain fibers reduce cardiovascular symptoms in 5 subjects out of 10 who were given whole grains than 5 with simple carbohydrates

Ludwig DS et  al., [ 2007] (5)fabricated that how( low glycemic index food helped in reliving from diseases) . He performed experiment on 10 subjects out of which 5 were given high glycemic food and 5 were given low glycemic food . After 2 months he observed that 5 with high GI got more fat and  more prone to obese rather than 5 with low  GI. So he concluded that we should take food that have low GI.

Lann D et  al.,[2007] (9)fabricated that ( Insulin resistance is the cause of metabolic syndrome) . They took 10 subjects out of which 5 were given high calorie diet and 5 were given low  to moderate calorie . After 4 months they observed 5 with high calorie received more insulin resistance and in turn came more close to diabetes type II than 5 with low calorie diet.

Eyre H et  al.,  [2004](2)  evaluated( Prevention of cardiovascular disease and diabetes ), different cardiovascular disease are caused by improper diet and in taking lots of  packed foods and junk foods . They performed an experiment on 20  subjects and 10 subjects were  given the unhealthy foods and remaining were given healthy foods . After 3 months those subjects who were on junk foods acquired more cholesterol level in plasma than those on healthy foods. So it is concluded that diet plays a vital role in life.

Stampfer MJ et  al., [2000](3) evaluated that( Primary prevention of coronary heart disease in women through diet and lifestyle) . Enough solid evidence now exists to offer women several fundamental strategies for healthy eating. They include emphasizing healthful unsaturated fats, whole grains, good protein “packages,” and fruits and vegetables; limiting consumption of trans and saturated fats, highly refined grains, and sugary beverages; and taking a multivitamin with folic acid and extra vitamin D as a nutritional safety net. A diet based on these principles is healthy through virtually all life stages, from young adulthood through planning for pregnancy, pregnancy, and on into old age.

III. Theory

 ( a). Carbohydrates (5)

               Dietary carbohydrates are the chief source of energy.  They contribute 60 to 70 % of total calories requirement of body . These are less in cost .Carbohydrates are most abundant dietary constituent , despite that they are not essential nutrients to a body. 

These are classified into two categories:

1. Carbohydrates utilized by the body like starch, glucose, lactose ,glycogen etc.

2.  Carbohydrates that are not utilized by body like   cellulose, pectin,  gums  etc .

            Among the carbohydrates utilized by body starch is the most abundant .It has several advantages like satiety value ,bland taste, ,slow digestion and absorption. Excessive intake of sucrose can cause dental problems, and an increase in plasma  lipid  level associated with many health complications.

Function of carbohydrates

 1.Major source of energy :These are principle source of energy. Supplying 60 to 80 % of  calorie requirement of body.

2. Protein sparing action :  protein plays a vital role in bodybuilding and growth The wasteful expenditure of protein to meet energy needs of a body should be curtailed. Carbohydrates come to rescue and spare protein from being misused for calorie purpose.

3. Absolute requirement by brain: The brain and parts of CNS are dependent on glucose for their function .So prolong hypoglycemia can cause irreversible brain damage.

4. Required for oxidation of fat:  Acetyl CoA  is the product formed in fatty acid oxidation so it needs citric acid and oxaloacetate which  is derived from carbohydrates .

5. Synthesis of fat : Excess consumption of carbohydrates leads to the formation of fat which is stored in adipose tissue.

6. Importance of non digestible carbohydrates: These are not utilized by the body though they are Important since they help in bowel motility , prevent constipation etc.(5)

Sources of carbohydrates: (6) 

                 There are two types of sources of carbohydrates complex carbohydrates and simple carbohydrates (table 1) :

Complex		Simple
Oats		White rice
Brown rice		Banana
Chappatis/rotis		Ice cream
Quinona		Fruits
Brown Bread		Sugary products
Whole grain cereals		White potato
Sweet potato

 Table no. 2  (6) representing amount of Carbohydrates for different type of working   people.

	Sedentary Work		Moderate work		Heavy work
	Veg.	Non-veg	Veg.	Non-veg	Veg.	Non-veg
Cereals	400g	400g	475g	475g	650g	650g
PULSES	70g	55g	80g	65g	80g	65g
Green leafy vegetables	100g	100g	125g	125g	125g	125g
Other vegetables	75g	75g	75g	75g	100g	100g
Roots and tubers	75g	75g	100g	100g	100g	100g
Fruits	30g	30g	30g	30g	30g	30g
Milk	200g	100g	200g	100g	200g	100g
Fats and oils	35g	40g	40g	40g	50g	50g
Meat and fish		30g		30g		30g
Eggs		30g		30g		30g
Sugar&jaggery	30g	30g	40g	40g	55g	55g

 (b) Protein

              Protein have been traditionally regarded as bodybuilding foods . As far as possible carbohydrates spare proteins and make the latter available for bodybuilding process.  When we take a proteineus food it breaks down into amino acid. There are two types of amino acid

Essential amino acids :

The nutritional importance of proteins is based on the content of essential amino acids . There are ten  essential amino acids :

1.       Arginine

2.       Valine

3.       Histidine

4.      Isoleucine

5.      Leucine

6.      Lysine

7.      Methionine

8.      Phenylalanine

 

     Tryptophan and threonine of these two arginine  and histidine are semi essential. Cysteine and tyrosine  can respectively spare the reqirements of methionine and phenylalanine .(1)

Conditionally essential amino acid (8)

             There are two types of nitrogen balance :

Positive nitrogen balance : This is a state in which nitrogen in take is the synthesis of certain non essential amino acids is limited to the extent of meeting bodies requirements in a healthy state. In patho- physiological  conditions like surgery, wound healing, sepsis, injury etc. The non essential amino acids become conditionally essential amino acids and needed to be supplemented in the diet eg arginine,  cysteine,  glycine,  proline etc..

            Dietary protein is almost an exclusive source of nitrogen for body.Thus the nitrogen balance truly represents the protein utilization  and its loss from the body. Nitrogen balance is determined by comparing the intake of nitrogen and excretion of nitrogen. A normal healthy adult is in a nitrogen equilibrium state since dietary intake is equal to the loss through urine,feces and sweat.

               The term fudge factor is used to represent nitrogen lost in feces , sweat and higher than the output .Some amount of nitrogen is retained in the body causing a net increase in in the body protein. It is observed in growing children, pregnant woman or during recovery from illness .

            Negative nitrogen balance: This is a situation in which nitrogen output is greater than input. The result is that the nitrogen is lost from the body depleting the body protein. Prolonged negative nitrogen balance  may lead to death. This is sometimes observed in  children suffering from kwashiorkor or marasmus. It may be the cause of inadequate dietary intake of protein.(6)

Sources of protein (9)

      There are variety of sources of protein are:

            1.Red meat (mutton ,beef )

            2. chicken

            3. eggs

            4.  milk and milk products

            5. Tofu

            6 Fish

            7. soya  products

          Some foods are there which are not complete protein but they can be made complete by          good combinations like cereals with milk, grains with nuts, Legumes with nuts and seeds,    cereals with pulses. But still animal protein is far superior than plant based protein.

Requirement of protein

           The requirement of protein depends on its nutritive value, calorie intake physiological and physical; states of an individual.   For an adult 0.8 to 1g protein /kg of bodyweight/day is adequate. The requirement should be double for growing children , pregnant  woman, etc.

Assessment of Nutritive value of proteins. (9)

          Knowledge on the quantity of dietary protein alone is not sufficient to evaluate the nutritional importance of proteins . This is in contrast to dietary carbohydrates and lipids. The quality of the proteins which depends on the composition of essential amino acids is more important. Several laboratory methods are in use to assess the nutritive value of proteins. Four methods are—protein efficiency ratio, biological value, net protein, utilization and chemical score.

Protein efficiency ratio (PER)

           This test consists of feding weaning (21 day old) albino rats with a 10%test protein diet and recording the gain in body weight for a period of 4 weeks. PER is represented by gain in the weight of rats per gram protein ingested.

PER=Gain in body weight (g)/Protein ingested.

Biological value (BV)

The Biological value (BV) of protein is defined as the percentage of absorbed nitrogen retained by the body.  BV = Nitrogen retained/Nitrogen absorbed x100 

           For the measurement of BV ,the experimental animals ,namely weaning albino rats are chosen. They are first fed with a protein free diet for 10 days.Then they are kept on a 10% protein diet to be tested for BV. Urine and feces are collected for both the periods i.e. protein free diet and protein diet. Nitrogen is estimated in the diet ,feces and urine samples. Biological value  can be  calculated by the following formula:

BV=(N absorbed-an lost in metabolism)/N absorbedx100.

           The biological value provides a reasonably good index for the nutritive value of proteins . But unfortunately this method has an inherent  drawback . IT cannot take into account the nitrogen that might be lost during the digestion process. For instance, if the ingested nitrogen is 100mg,absorbed is 10mg and retained is 8mg, the BV 8/10x100=80. This figure is erroneous, since the major part of the protein (90mg) did not enter the body at all for utilization.(4)

Net Protein utilization(NPU) (7)

           NPU is a better nutritional index than BV ,since it takes into account the digestibility factor. The experimental procedure for NPU is same as BV.Net protein utilization can be calculated as  NPU=Nitrogen retained/Nitrogen ingestedx100.

Chemical Score (7)                                              

            This is based on the chemical analysis of the protein for the composition of essential amino acids which is then compared with a reference protein (usually egg protein). The chemical score is defined as the ratio between the quantity of the most limiting essential amino acid in the test protein to the quantity of the same amino acid in the egg protein ,expressed as percentage.

Chemical Score=mg of the limiting amino acid/g test protein /mg of the same amino acid/g egg protein.

           The chemical score of egg protein , for any one of the essential amino acids is taken as 100 and the rest of the proteins are compared. The four methods are applied for assessment of nutritive value of proteins (table 3):

Source of protein	PER	BV	NPU	Chemical Score	Limiting amino acids
EGG	4.5	94	90	100	NIL
Milk	3.0	84	75	65	S-Containing amino acids
Fish	3.0	85	70	60	Tryptophan
Meat	2.7	75	76	70	S-Containing amino acids
Rice	2.2	68	60	60	Lysine, Threonine
Wheat	1.5	58	47	42	Lysine, Threonine
Bengal Gram	1.7	58	47	45	S-Containing amino acids
Red Gram	1.5	57	46	45	S-Containing amino acids
Groundnut	1.7	55	45	44	Lysine, Threonine, Amino acids
Soyabean	2.1	65	55	55	S-Containing amino acids

            The animal proteins  are  superior  in their nutritive value compared to the proteins of vegetable origin. Further, some of the essential amino acids are limiting in certain foods. For instance ,rice and wheat proteins are limiting in Lysine, Threonine while the protein of Bengal Gram is limited in sulfur-containing amino acids(methionine and cystine)

            It is fortunate that humans(world over) have the habit of consuming a mixed diet, with different foods simultaneously. This helps to overcome the deficiency of   certain essential amino acids in one food by being supplemented from the others. This phenomenon is referred to as mutual supplementation. For instance  ,an  Indian diet with cereals (rice, wheat) is taken along with pulses (dal). The limitation of Lysine and Threonine   in cereal proteins is overcome by their supplementation from dal proteins. Simultaneously , the limitation of sulfur-containing amino acids in dal is also compensated by the cereals which are rich in them.

         The nutritive value of protein of a particular food can be enhanced by appropriate combination with other foods. Due to the consumption of mixed diets ,dietary deficiency of essential amino acids is most uncommon. Further ,  the principal of mixed diet takes care to supply adequate quantities of essential amino acids to the people subsisting on pure vegetarian  diets. It has to be remembered that the effect of mutual supplementation in proteins is best observed with the  same meal (or at least on the same day). (1)

(c)Nutritional Importance of Lipids

          Triacylglycerols(fats and oils) are the concentrated dietary source of fuel contributing 15-50%of the body energy requirements .Phospholipids and cholesterol (from animal sources)are also important in nutrition.

Major traditional functions of lipids: (4)

          Dietary lipids have two major nutritive functions .

 1.Supply triacylglycerols that normally constitute about 90% of dietary lipids which is a concentrated source of fuel to the body .

 2.Provide essential fatty acids and fat soluble vitamins(A,D,E and K)

          Triacylglycerols are the most predominant storage from energy. There are two main reasons for fat being the fuel reserve of the body .

1.       Triacylglycerols(TG) are highly concentrated form of energy, yielding 9 cal/g. In contrast to carbohydrates and proteins that produce only  4 cal/g. This is because fatty acids found in TG are in the reduced form

2.       The Triacylglycerols are non polar and hydrophobic  in nature, hence stored in pure form  without any association with water(anhydrous form). On the other hand , glycogen and proteins are polar. One gram of glycogen combines with 2g of water for storage.

One gram of fat stored in the body  yields nearly  six times as much energy as one gram of (hydrated) glycogen. In a healthy adult individual(weighing 70 kg), about  10-11 kg of fat is stored (mostly in adipose tissue) which corresponds to a fuel reserve of 1 ,00,000 cals.If this much of energy were to be stored as glycogen (instead of fat) then the weight of the person would increase by at least 55kg

 Long chain fatty acids (of fat) are the ideal storage fuel reserves of the body. Fat can support the body’s energy needs for long periods of food deprivation. In extreme cases ,humans can fast and survive for 60-90days and the obese persons can survive even longer (6months to one year) without food.(8)

Hibernating animals provide good example for utilizing fat reserve as fuel. For instance bears go on hibernation for about 7 months  and during the entire period , the energy is derived from the degradation of fat stores. The ruby throated humming birds fly , non stop from New England  and West Indies(2400km), at a speed of 40km/hr. for 60 hrs. This is possible only due to the stored fat.

Essential Fatty Acids

          The unsaturated fatty acids which the body cannot synthesize and therefore must be consumed in the diet are referred to as essential fatty acids(EFA).

           The fatty acids—linoleic and linolenic acid cannot be synthesized by humans. In  a strict sense  only these two are essential fatty acids.Arachidonic acid can be synthesized from  

            Linoleic acid in some animal species including man. However, the conversion efficiency of Linoleic acid to Arachidonic acid is not clearly known in man. And for this reason some nutritionists recommend that it is better to include some amount of Arachidonic acid also in the diet.

Functions of EFA(10)

1.Essential fatty acids are the structural components of biological membranes.

2. Participate in the transport and utilization of cholesterol.

 3.Prevent fat accumulation in the liver.

4. Required for the synthesis of prostaglandins.

5. Maintain proper growth and reproduction of  

     the organisms.  (9)

 Deficiency of EFA(10)

               The EFA deficiency in humans is characterized by a scaly dermatitis on the posterior and lateral parts limbs and buttocks. This condition is referred to as phrynoderma or toad skin.

EFA contain of foods 

           The essential fatty acids more frequently called polyunsaturated fatty acids (PUFA) are predominantly present in vegetable oils and fish oils. The rich vegetable sources include sunflower oil, cotton seed oil, corn oil, soyabean oil  etc. The fat of animal origin (exception fish) contain less PUFAe.g.butter,fat of meat,pork.

Dietary intake  of EFA (11)

          Nutritionists recommend that at least 30%of the dietary fat should contain PUFA. Very high intake of PUFA(i.e totally replacing saturated fatty  acids) may not be advisable. This is due to the fact that excess PUFA unless accompanied by antioxidants (Vitamine E,carotenes) is believed to be injurious to the cells due to the overproduction of free radicals.Normally, from the nutrition point of view, a high ratio of polyunsaturated fatty acids to saturated fatty acids (PS ratio) is believed to reduce the risk of coronary heart diseases.

Conditionally essential fatty acids:

           The fatty acids that become essential in developmental or disease conditions are regarded as conditionally essential fatty acids. Supplementation of DHA to meet the needs of developing brain in children  and DHA and EPA to reduce the risk of heart diseases are good examples of conditionally EPA.

Trans Fatty Acids(TFA)

            TFA posses double bonds and are formed during partial hydrolysis of vegetable oils. TFA are widely used in food industry due to long shelf life.They increase LDL and decrease HDL and thus promote altherogenesis and heart diseases . Therefore,TFA should be avoided in the diet as far as possible.(10)

Cholesterol in  Nutrition

                        Animals food are the only dietary sources of Cholesterol. However, the role of   

            dietary Cholesterol on plasma Cholesterol is less important than the amount and types of   

            fatty acids consumed.

 SOURCES OF FAT (10)

      There are a variety of fat sources( table 4):

Unsaturated fat		Saturated fat
Olive oil		Egg Yolk
Avocadro oil		Milk fat
Coconut oil		Refined oils
Mustard oil

         Saturated fats are those fats that causes various health problems.They get deposited  in the blood vessels and cause atherosclerosis.Unsaturated fats are good fats they does not cause health issues.

Requirement of fats

           Consumption of fats and oils depends on their contribution to energy needs of the body. The recommended intake of fat intake is around 20to 30% of daily calorie requirement containing about 50% of PUFA.(1)

(d) Vitamins

         Vitamins may be regarded as organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism. Generally,vitamins are not synthesized by the body and therefore need to be supplied through the diet.

Classification of Vitamins:

        There are about 15 vitamins essential for humans. They are classified as fat soluble (A,D,E, and K) and water soluble(C AND B-GROUP).The B-complex vitamins may be sub-divided into energy-releasing(B₁, B₂,B₆,biotin) and hematopoietic(folic acid and B₁₂).Most of the water soluble vitamins exert the functions through their respective co-enzymes while only one fat soluble vitamin K has been identified to function as a co-enzyme.Synthesis of vitamins by intestinal  Bacteria:  

          Vitamins are not synthesized in the body. However, the bacteria of the gut can produce some of the vitamins required by human and animals. The bacteria mainly live and synthesized vitamins in the colon region where the absorption is relatively poor. Some of the animals (e.g. rat, deer etc.) eat their own feces.This phenomenon known as coprophagy.

          As far as human are concerned, it is believed that the normal intestinal bacterial synthesis and absorption of vitamin K and biotin may be sufficient to meet the body requirements. Other B-complex vitamins,  the synthesis and absorption are relatively less. Administration of antibiotics often kills the vitamin synthesizing bacteria present in the gut, hence additional consumption of vitamins is recommended. (13)

Fat Soluble Vitamins—General:

         The four vitamins namely A,D,E and K are known as fat or lipid soluble. Their availability  in the diet ,absorption and transport are associated with fat.They are soluble in fats and oils and also the fat solvents(alcohol,acetone etc.). Fat soluble vitamins can be stored in liver and adipose tissue. They are not readily excreted in urine. Excess consumption of these vitamins (particularly A and D) leads to their accumulation and toxic effects.

Water Soluble Vitamins –General

       The water soluble vitamins are a heterogenous group of compounds since they differ chemically from each other. The only common character shared by them is their solubility in water. Most of these vitamins are readily excreted in urine  and they are not toxic to the body. Water soluble vitamins are not stored in the body in large quantities(except B₁₂). For this reason, they must be continuously supplied in the diet. Generally, vitamin deficiencies are multiple rather than individual with overlapping symptoms. It is often difficult to pinpoint the exact biochemical basis for the symptoms. The dietary deficiency of a single B-complex vitamin is rather rare, since nutritionally poor diets are often with multiple nutrient or vitamin deficiencies. The water soluble vitamins from coenzymes  that participate in a variety of biochemical reactions, related to either energy generation or hematopoiesis. It may be due to this reason that the deficiency of vitamins results in a number of overlapping symptoms. The common symptoms of the deficiency of one or more vitamins involved in energy metabolism include dermatitis, glossitis,(red and swollen tongue),cheilitis(rupture at the corners of lips), diarrhea, mental confusion, depression, malaise and neurological manifestations.(11)

Vitamers

       The term vitamers represents the chemically  similar substances that possess qualitatively similar vitamin activity.

·         Retinol, retinal and retinoic acid are vitamers of vitamin A

·         Pyridoxin, pyridoxal and pyridoxamine are vitamers of vitamin B₆.

Sources of vitamins

1.      Animal sources contain vitamin A The best sources are liver ,kidney, egg yolk, cheese etc ,vegetables also contain A carotene.

2.      Fish liver oil , egg yolks, sunlight are good sources of vitamin D.

3.      Many vegetable oils are good sources of vitamin E( wheat germ oil, cotton seedoil etc).

4.      Cabbage , cauliflower , alfa alfa  ,egg yolk ,meat , milk etc are good sources of vitamin K.

5.      Cereals ,  pulses, oils , milk  and  its  products ,meats,  yeast   ,fish ,  citrus   fruits    etc   are sources of vitamin B complex  and vitamin C.

Function of vitamins:

          Vitamin A is involved in vision ,proper growth, differentiation, and maintenance of epithelial cells. Its deficiency results in night blindness.

           The active form of vitamin D is calcitriol which functions like a steroid hormone and regulates plasma levels of calcium and phosphate. Vitamin D deficiency leads to rickets in children and osteomalacia in  adults.

            Vitamin E is a natural antioxidant necessary for normal reproduction in many animals.

             Vitamin K has a specific coenzyme function. It catalyses the carboxylation of glutamic acid residues in blood clotting factors (II,VII,IX,and X) and converts them to active form.

             Thiamine (B₁) as a cocarboxylase(TPP) is involved in energy releasing reactions. Its deficiency leads to beri-beri.

              The coenzymes  of riboflavin (FAD and FMN) and niacin (NAD and NADP) take part in a variety of oxidation-reduction reactions connected with energy generation. Riboflavin deficiency results in cheilosis and glossitis and niacin leads pellagra.

              Pyridoxal phosphate (PLP), the coenzyme of vitamin B₆ is mostly associated with amino acid metabolism . PLP participates in  transmination, decarboxylation, deamination and  condensation reactions.

             Biotin (anti-egg white injury factor) participates as a coenzyme in carboxylation reactions of gluconeogenesis, fatty,acid synthesis etc.

             Coenzyme A(of pantothenic acid) is involved in the metabolism of carbohydrates, lipids, and amino acids and their integration.

           Tetrahydrofolate (THP) the coenzyme of folic acid participates in the transfer of  one carbon units (formyl,methyl etc) in amino acid and nucleotide metabolism. Megaloblastic anemia  is caused by folic acid deficiency.

         Vitamin B₁₂ has two coenzymes deoxyadenosylcobalamin and methylcobalamin. B-12 deficiency results in pernicious anaemia.

         Vitamin c is involved in the hydroxylation of proline and lysine in the formation of collagen. Scurvy is caused by ascorbic acid deficiency. Therapeutic use of megadoses  of vitamin c to cure everything from common cold to cancer has become controversial.(12)

(e)  Mineral (15)

        The mineral(inorganic)elements constitute only a small proportion of the body weight. There is a wide variation in their body content. For instance, calcium constitutes about 2% of body weight while cobalt about 0.00004%.

General Functions:

           Minerals perform several vital functions which are absolutely essential for the very existence of the organism. These include calcification of bone, blood coagulation , neuromuscular irritability, acid- base equilibrium, fluid balance and osmotic regulation.

         Certain minerals are integral components of biologically important compounds such as hemoglobin (Fe),thyroxin(I),insulin (Zn) and vitamin B₁₂(CO.). Sulfur is present in thiamin, biotin, lipoic acid and coenzyme A. Several minerals participate as cofactors for enzyme in metabolism(eg MG ,Mn ,Cu ,Zn, K). Some elements are essential constituents of certain enzymes(eg Co, Mo, Se).

Classification:

        The minerals are classified as principal and trace elements:

        The seven principal elements (Macro elements) constitute 60-80% of the body’s inorganic material. These are  calcium, phosphorus, magnesium, sodium,potassium , chloride and sulfur.

       The principal elements are required in amounts greater than 100mg/day.

       The micro-minerals are required in amounts less than 100mg/day. They art subdivided  into three categories.

Essential trace elements:

    Iron, copper ,iodine, manganese ,Zinc ,molybdenum, cobalt,fluorine, selenium and chromium.

Possibly essential trace elements:

    Nickel, Vanadium,  cadmium and barium.

Non essential trace elements

  Aluminium, lead, mercury,boron, silver,bismuth etc

 Summary of  macro and micro elements are tabulated( two table) below:

      A summary of the major characteristics of principal elements(macroelements)(table 5) (1)

Elements	Major Function	Deficiency Disease/symptoms	Recommended Dietary allowance.	Major sources
Calcium	Constituent of bones and teeth	Rickets, Osteomalacia  and osteoporosis	0.8-1.0g/d	Milk,leafy vegetables and beans
Phosphorus	Constituent of bones and teeth	Rickets, Osteomalacia	0.8-1.0g/d	Milk,leafy vegetables and cereals
Magnesium	Constituent of bones and teeth	Neuromuscular weakness,irritation.	300-350mg/d	Cereals ,vegetables, fruits, milk
Sodium	Chief cation of extracelluar fluids,acid balance, osmotic pressure,nerve and muscle function	Almost unknown on normal diet.	5-10g/d	Table salt, salt added foods.
Potassium	Chief cation of  intracelluar fluids, acid balance, osmotic pressure,nerve and muscle function	Muscular weakness, mental confusion	3-4g/d	Fruits ,nuts , vegetables
Chlorine	Regulation of acid base Balance, formation of HCL	Almost unknown on normal diet.	5-10g/d	Table salt
Sulfur	Constituent of sulfur containing amino acids, contain vitamins(thiamine,biotin) and other compounds(hepartin,chondroitin,sulfate)	Almost unknown	-	Sulfur containing amino acids.

    A summary of the major characteristics of trace elements(microelements).(table 6) (1 )

Elements	Major Function	Deficiency Disease/symptoms	Recommended Dietary allowance.	Major sources
Iron	Constituent of  heme (haemoglobin,myoglobin  etc	Hypochromic,microcytic anemia	10-15mg/d	leafy vegetables, meats(liver, heart) and iron cookware.
Copper	Constituent of enzymes	Anemia, monke’s disease.	2-3mg/d	leafy vegetables, meats(liver, heart) and cereals
Iodine	Constituent of thyroxin and triodothyrinine	Cretinism, goiter,myxedema.	150-200µg/d	Iodized salt, sea foods ,
Manganese	Co- factor for enzymes.	Almost unknown	2-9mg/d	Cereals , leafy vegetables
Zinc	Co- factor for enzymes.	Growth retardation ,poor wound healing,hypogonadism	10-15mg/d	Meat,fish , milk
Molybdenum	Constituent of enzymes	Almost unknown	75-250µg/d	vegetables
Cobalt	Constituent of vitamin B12 required for the formation of erythrocycles)	Pernicious anemia( as in vitamin B12 deficiency)	5-8 µg/d	Foods of animal origin.
Fluorine	Helps in the proper formation of bones and teeth.	Dental caries, osteoporosis	2-4mg/d	Drinking water
Selenium	Involved in antioxidant function along with Vitamin E	Muscular degeneration, cardio myopathy	50-200 µg/d	Organ meats , sea foods
Chromium	Promotes insulin function (as glucose tolerance factor	Impaired glucose tolerance	10-100 µg/d	Brewar’s yeast, meat, whole grains.

(f)   Fiber  in Nutrition (14)

                 The complex carbohydrates that are not digested by the human enzymes are collectively referred to as dietary fiber . Soluble fibers, mostly found in fruits and legumes, dissolve  in water form gels (e.g pectins, gums, mucilages ). Insoluble fibers  present in vegetables and grains, absorb water and swell up (e.g.cellulose ,hemicelluloses, lignin). Certain fibers (e.g pectins,gums) are digestible by intestinal bacterial enzymes. It may be stated that once regarded as a nutritional waste, a lot of importance is now given to dietary fiber in human health.

Beneficial effects of fiber

1.      Prevents constipation : Fiber can absorb 10-15 times its own weight of water by drawing fluid into the  lumen of the intestine. This increases bowel motility and prevents constipation besides decreasing the risk of hemorrhoids and diverticulosis .

2.      Eliminates bacterial toxins: Fiber also absorbs toxic compounds produced by intestinal bacteria and helps in their easier expulsion.

3.      Decreases GIT cancers: The lower incidence of cancers of gastrointestinal tract(e.g. colon and rectum) in vegeterians compared to non-vegeterians  is attributed to dietary fibre.

4.      Improves glucose tolerance: Fiber improves glucose tolerance by the body. This is mainly done by a diminished rate of glucose absorption from the intestine.

5.      Reduces plasma cholesterol level: Fiber decreases the absorption of dietary cholesterol from the intestine. Further, fiber binds with the bile salts and reduces their enterohepatic circulation .Thus, degradation of cholesterol to bile salts and its disposal from the body is increased.

6.      Satiety value: Dietary fiber adds to the weight of the foodstuff ingested and gives a sensation of stomach fullness , giving satiety without consumption of excess calories.

Adverse affects of fiber:

Some of the food fads went to the extent of ingesting huge quantities of rice bran to achieve all the benefits of fiber. This led to several complications . In general, the harmful effects are mostly observed in people consuming large quantities of dietary fiber.

1. Digestion and absorption of protein are adversely affected.

2. The intestinal absorption of certain minerals (e.g.Ca, P ,Mg) is decreased.

3.Intestinal bacteria ferment some fibers, causing flatulence and often discomfort.

 Drinking plenty of water along with fiber is advocated to reduce adverse effects of fiber.

 Sources of dietary fiber:

            Fruits, leafy vegetables , whole wheat legumes, rice bran etc. are rich sources  of fiber. The ideal way to increase fiber intake is to reduce intake of refined carbohydrates besides eating vegetables , fresh fruits and whole  grains . In general vegetarians consume more fiber  than   non-vegetarians . An average daily intake of about 30g fiber is recommended.                                               

                       

(g) Weight control, exercise (10)

           Body weight sits like a spider at the center of a web of health and disease. Excess weight predisposes an individual to the development of a host of chronic conditions. The higher the body mass index (BMI) > 25 kg/m², the greater the prevalence of abnormal blood glucose, lipids and blood pressure; hypertension and cardiovascular disease; diabetes; many cancers; gallstones; sleep apnea; complications of pregnancy; infertility; and premature mortality. Under the current national guidelines, a BMI between 18 and 25 kg/m² is considered optimal, and the best health experience is achieved by avoiding increases in weight during adulthood.

         Maintaining a healthy body weight, or losing weight, is a direct function of calories consumed and expended. Portion control is essential for weight maintenance. The percentage of calories from dietary fat has little relationship with weight maintenance, while low consumption of sugary beverages and trans fats and higher intake of dietary fiber appear to be helpful. Regular exercise and the avoidance of extreme inactivity, such as excessive television watching, are also integral strategies for weight control. A supportive social and physical environment are also important.(16)

IV. Conclusion (16)

        Although much solid information on optimal diets has emerged, the full picture of the relationships between diet and health will take years of further research to fill in. Yet several fundamentals have been established and are unlikely to change significantly. These include the seven general strategies listed in Table 7

          It is impossible to cover all this ground in a 5-minute office visit. However, it is possible to make several general points, offer a handout, and direct a patient to more information. If a patient is overweight, the most important general points should be about portion control, avoiding sugary beverages, and exercise. Weight is probably at least as important for long-term health as are dietary components. For a patient whose weight is in the healthy range, reinforce that it is prudent to avoid trans and saturated fats and emphasize unsaturated fats, replace highly refined grains with whole grains, and choose healthful sources of protein. The Healthy Eating Pyramid  offers a good visual reminder of these points and other essentials of healthful eating.

        The seven strategies listed in Table 7 aren’t quite as pithy as food writer Michael Pollan’s extraordinary seven-word summary of healthy eating: Eat food. Not too much. Mostly plants.(16)

Table-7 (16)

Elements of healthy eating

Choose healthy fats over unhealthy fats	Avoid trans fats which are generally found in commercially  baked products and deep fried restaurant food. Limit intake of saturated fats mostly red meat,butter, milk,and other dairy products(under 8% of calories[17 grams*]) Emphasize polyunsaturated fats from olives and olive oil, canola,peanut, and other nut oils, almond, cashews, peanuts,and nuts and nuts butter, avocados,sesame,pumpkins and other seeds(10-15% of calories [22-27 grams*]) Emphasize polyunsaturated fats from vegetable oils  such as corn, soyabean and sunflower oils, walnuts,fatty fish such as salmon, herring and anchovies(8-10% calories[17-22 grams*])
Choose slowly digested carbohydrates over highly refined ones	Limit intake of sources of rapidly digested carbohydrates such as white flour , white rice etc. in their place emphasize whole grains such brown rice quinoa, wheat berries, whole fruits and vegetables and nuts. Aim for at least six serving of whole grains a day. Choosing a whole grain breakfast cereal and whole grain bread are excellent start.
Pick the best protein  packages by emphasizing plant source of protein rather than animal source	Adopting a flexitarian approach to protein as long term health pay offs .Aim for at least half of protein from plants beans ,nuts etc. Choose fish, eggs, poultry for most of the rest with small amount of red meat and dairy making of the balance.
Accentuate fruits and vegetables	Considered five serving of fruits and vegetables are daily minimum. Eat for variety and color. Each day try to get at least one serving of a dark green leafy vegetables, a yellow or orange fruit or vegetables are red fruit and vegetables and the citrus fruit. Fresh is usually best.
Opt for low calorie hydration	Water is the best choice for hydration. Coffee and tea in moderation are generally safe and healthy. If milk is the part of diet then low fat milk is best. Avoid sugar loaded drinks like soda, fruit drinks etc. Limit fresh fruit juice to one glass a day.
Meet the daily recommendation  for vitamins and  minerals.	Taking a RDA level multivitamin-multimineral supplement each day that contains folic acid , and 1000 IU of vitamin D provide an inexpensive nutritional safety net. Many pre-menopausal women need extra iron and additional calcium.
Daily exercise	Calories expended are as important for good health as the quality and quantity of calories consumed. 30 minutes physical activities such as brisk walking on most ,if not all, days of the week.