The science of nutrition
Last Updated: Wednesday, August 03, 2011, 00:00
  

We need food to grow and prolong life. We consume various types of food according to our age, work or lifestyle. Geography and socio-economic factors greatly influence the availability and consumption of food.
Nutrition
Nutrition is the food that provides energy and good health. The human body needs nutrition or nourishment on a timely basis.
Nutrition science deals with the relationship between diet and health. Diet can be defined as the habitual nourishment intake. A balanced diet is needed to promote and maintain good health and longevity. It is vital for preventing chronic health risks, such as obesity heart disease, cancer and diabetes. Foods contain nutrients that help the metabolic functions in our body. Insufficient intake of these vital nutrients leads to improper functioning the body. This state is called nutritional deficiency.

A healthy diet involves appropriate intake of all nutrients and water. Nutrients are chemicals that organisms need to live and grow. They are used to build and repair tissues, regulate body processes etc. Nutrients needed in very small amounts are called micronutrients and those nutrients needed in larger quantities are called macronutrients. Organic nutrients include carbohydrates fatsproteins and vitamins. Inorganic nutrients are water, dietary minerals and oxygen. Nutrients are also classified as essential or non-essential. If a nutrient is obtained from an external source when an organism is unable to synthesizedit internally or insufficiently it called an essential nutrient. Non-essential nutrients are those which can be synthesized by the body.

Carbohydrates provide energy. They are compounds made up of sugars. Carbohydrates are classified by their number of sugar units: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Proteins help build body tissue. They are organic compounds that consist of the amino acids joined by peptide bonds. The body cannot manufacture some of the amino acids (termed essential amino acids); the diet must supply these.
Fats are a component of all cell membranes and are an important source of stored energy in the body. Fats consist of a glycerin molecule with three fatty acids attached. Fatty acids are unbranched hydrocarbon chains, connected by single bonds alone (saturated fatty acids) or by both double and single bonds (unsaturated fatty acids). The body does not manufacture certain fatty acids (termed essential fatty acids) and the diet must supply these.
Vitamins are organic compounds essential for the cellular functions of the body. They are chemical substances that help the body use energy, build proteins, make cells, and repair injuries. Vitamins are divided into two general categories: fat soluble and water soluble. The fat soluble vitamins are A, D, and E. Vitamin A is necessary for eyes, bones, and skin. Vitamin D is necessary to make bones and teeth, and it allows the body to use calcium from the diet. Vitamin E is important for the immune system and for the cardiovascular system.
The water soluble vitamins are vitamin C and the B vitamins. Vitamin C is important for fighting infection and for using the stored energy in the body. Vitamin C is generally found in citrus fruits and other vegetables like tomatoes and peppers. The B vitamins are important for building blood cells, nerve cells, and are vital for many of the body`s chemical reactions. These are found in many meats and vegetables.
Minerals, such as calcium, iron, zinc, and magnesium, are also essential for health.
Nutritional deficiency diseases

Deficiencies

1. Proteins/fats/carbohydrates

a) Protein-energy malnutrition
* Kwashiorkor
* Marasmus
* Mental retardation

2. Dietary vitamins and minerals

a) Calcium
* Osteoporosis
* Rickets
* Tetany
b) Iodine deficiency
* Goitre
c) Iron deficiency
* Anemia

d) Selenium deficiency
* Keshan disease

e) Zinc
* Growth retardation
f) Thiamine (Vitamin B1)
* Beriberi
g) Niacin (Vitamin B3)
* Pellagra
h) Vitamin C
* Scurvy
i) Vitamin D
* Osteoporosis
* Rickets

Dietary recommendations by World Health Organization

* Achieve an energy balance and a healthy weight
* Limit energy intake from total fats and shift fat consumption away from saturated fats to unsaturated fats and towards the elimination of trans-fatty acids
* Increase consumption of fruits and vegetables, legumes, whole grains and nuts
* Limit the intake of simple sugar
* Limit salt / sodium consumption from all sources and ensure that salt is iodized

Other recommendations include:

* Sufficient essential amino acids ("complete protein") to provide cellular replenishment and transport proteins. All essential amino acids are present in animals. Some plants (such as soy and hemp) give all the essential acids. A combination of other plants in a diet may also provide all essential amino acids. Fruits such as avocado and pumpkin seeds also have all the essential amino acids.
* Essential micronutrients such as vitamins and certain minerals.
* Avoiding directly poisonous (e.g. heavy metals) and carcinogenic (e.g. benzene) substances;
* Avoiding foods contaminated by human pathogens (e.g. E. coli, tapeworm eggs).

An unhealthy diet is a major risk factor for a number of chronic diseases including: high blood pressure, diabetes, abnormal blood lipids, overweight/obesity, cardiovascular diseases, and cancer.

The WHO estimates that 2.7 million deaths are attributable to a diet low in fruit and vegetable every year. Globally it is estimated to cause about 19% of gastrointestinal cancer, 31% of ischaemic heart disease, and 11% of strokes.

Food Groups

There are five food groups:

• Fruits
• Vegetables
• Cereals and Pulses
• Dairy
• Poultry, Fish and Meat products

Some healthy foods

Cereals and Grains:

Brown Rice

Brown rice is a rich source of magnesium, selenium, manganese and fiber.

Oatmeal

Oatmeal is a good source of B complex vitamins, calcium, iron as well as protein

Wheat Germ

Wheat germ is a good source of vitamin E and Magnesium.

Pulses and Legumes:

Lentils

The heart healthy fiber along with isoflavones from lentils may have a protective effect against breast cancer.

Pinto Beans

Folates from pinto beans have a heart protective effect and also reduce any risk of birth defects in new born infants.

Tofu

A very good source of soy protein and omega 3 fatty acids, tofu offers cardiovascular benefits by lowering the low density lipoprotein cholesterol levels in the body.

Nuts and Oilseeds:

Peanuts

Polyunsaturated and monounsaturated fatty acid from peanuts helps to decrease the risk of cardiovascular diseases by a significant margin.

Walnuts

Omega 3 fatty acids in walnuts offer many protective effects to brain. It also have a heart protective effect.

Almonds

Monounsaturated fats from almonds may reduce your risk for heart disease and also lower your low density lipoprotein cholesterol. In addition to healthy fats, almonds are also packed with vitamin E, magnesium and potassium.

Flaxseeds
An excellent source of omega 3 fatty acids, flaxseeds have anti-inflammatory benefits and protect against heart disease, diabetes, bone disease and cancer.

Fruits and Vegetables:

Apples

Cardio-protective fiber and flavonoids from apples also prevent constipation. Apple juice can prevent the formation of kidney stones.

Apricots

Apricots are a rich source of beta carotene which gets converted to vitamin A in the body. Both beta carotene and vitamin A are potent antioxidants that help to scavenge the free radicals from the body and have a protective effect against many types of cancers and heart diseases.

Avocadoes

Oleic acid from avocadoes helps to lower the total cholesterol levels and even increase the high density lipoprotein levels in the body. Moreover avocado also provides a good dose of fiber. Try an avocado dip or guacamole in your burger instead of other fat loaded dressings.

Raspberries

This dark berry can be a perfect excuse to include whipped cream in your diet. Raspberries are packed with vitamin C and fiber. The ellagic acid present in this tiny berry may help to halt growth of cancerous cells.

Blueberries

They are a powerhouse of antioxidants including lutein, an important component for vision.

Cantaloupe

Cantaloupe is packed with two important antioxidants; vitamin C and vitamin A. The pro-vitamin A in cantaloupe promotes your lung health, protects your vision and vitamin C helps to fight against infection and boosts your immune system.

Kiwi Fruit

Vitamin C from kiwi protects the body from any oxidative damage and phytonutrients from this fruit protects the DNA.

Cranberries

These bright red berries are rich in vitamin C and dietary fiber. Cranberry juice is valued for its ability to reduce risk of urinary tract infection. The hippuric acid along with other components from the juice reduces E. coli adherence on the walls of the urinary track, as a result of which it is flushed out in the urine.

Raisins

Raisins are low in calories but rich in iron and fiber. The phenols from these little gems have an antioxidant property that helps to prevent oxygen based damage to the body. Add some raisins in your morning breakfast cereal to get the sweetness instead of adding sugar.

Plums

Phenols from plums offer a significant antioxidant protection by neutralizing the destructive free oxygen radicals that cause oxidative stress in the body.

Prunes

Fiber from prunes offers intestinal protection, improves bowel regularity and lowers cholesterol.

Figs

Figs are a good source of fiber and potassium that can help you to lose weight and maintain healthy blood pressure levels.

Papayas

Papaya is an excellent source of vitamin C and vitamin A, E and K. All these antioxidants along with the fiber in papaya surely promote good health and ward off a variety of diseases and conditions.

Pineapple

Bromelain from pineapple offers potential anti-inflammatory and digestive benefits. Pineapple is also a good source of manganese, ascorbic acid and thiamin which play a role in antioxidant defenses and energy production.

Limes and Lemons

Vitamin C from limes and lemons along with furocoumarins and limonene help prevent many types of cancers.

Tomatoes

Besides being rich in vitamin A and vitamin C, tomatoes are an excellent source of lycopene. Lycopene, a carotenoid acts as a potent antioxidant in the body and offers a protective effect against several types of cancer and cardiovascular diseases.

Onions

Onions are rich in flavanoids, most notably quercitin as well as many phytonutrients and vitamin C. The chromium from onions helps the body cells to respond well to the hormone insulin.

Artichokes

Silymarin, an antioxidant from artichokes helps to prevent skin cancer and the fiber helps to control cholesterol.

Asparagus

Asparagus is rich in folate, an essential vitamin for cardiovascular system. Make asparagus a healthy addition in your meal if you are planning to get pregnant as folate is also a great birth defect fighter.

Carrots

As the richest vegetable source of pro-vitamin A carotenoids, carrots offer protection against cancer and cardiovascular diseases. Beta carotene from carrots helps to promote good vision and also promote good lung health.

Kale

The organosulfur compounds in kale help prevent cancer, especially ovarian cancer. Kale is also a rich source of vitamin A, vitamin C and vitamin K which help to lower cataract risk, promote lung health and boost immunity.

Ginger

Gingerols from ginger may help reduce the queasiness. Other compounds in ginger may also help to ward off arthritis and migraine pain by blocking inflammation-causing prostaglandins.

Broccoli

It is packed with nutrients like vitamin C, beta carotene, vitamin A and folate. Sulforaphane and indole-3-carbinol in broccoli may have a protective effect against breast cancer. Steam or lightly microwave the broccoli, avoid overcooking.

Brussels Sprouts

Sulforaphane, a potent plant phytochemical present in Brussels sprouts have a protective effect against various types of cancer including bladder cancer. Besides they are also an exceptional source of vitamin K, vitamin C and fiber. Add some of these sprouts to your cold salads if you don’t prefer them as your main dish.

Spinach

Blessed with the healthiest nutrients like calcium, iron, potassium, magnesium, beta carotene, vitamin C, and vitamin B6, spinach can be considered a leafy powerhouse.

Sweet Potatoes

Unique root storage proteins in sweet potatoes have been proved to have potent antioxidant effects. Sweet potatoes are a sweet source of vitamin A, vitamin C, manganese, copper and dietary fiber.

Bok Choy

This Chinese cabbage is rich in brassinin, indoles and isothiocyanates all three may offer a protective effect against breast cancer.

Winter and Summer Squash

A variety of health promoting nutrients in both the squashes, like vitamin C, vitamin A, potassium, magnesium and fiber promote overall health.

Watercress

Vitamins C and vitamin E along with phenethyl isothiocyanate and beta-carotene in watercress helps to keep cancer cells at bay.

Garlic

The active components along with the sulfur compounds in garlic gives a typical pungent flavor but also helps to lower the low density lipoprotein cholesterol and also reduce the risk of colon and stomach cancer.

Olives

A concentrated source of vitamin E and monounsaturated fatty acids, olives provide cellular protection against free radicals support gastrointestinal health and prevent the development of colon cancer.

Dairy Products and Eggs:

Skim Milk

Vitamin A along with riboflavin in skimmed milk helps to maintain healthy vision and also reduces allergies and eczema. It also contain calcium and vitamin D.

Yogurt

Calcium in active-culture yogurt strengthens the bones and the bacteria help prevent yeast infections.

Eggs

Good quality proteins from eggs along with choline boosts brain health. Choline in egg yolks also helps reduce inflammation. Egg yolks are also a concentrated source of cholesterol.

Seafood:

Fish

Fatty cold water fish like tuna, mackerel and salmon are a rich source of omega 3 fatty acids. These good fats offer a protective effect against lowering cholesterol, protecting the heart, fighting inflammation to fighting many cancers and preventing Alzheimer`s disease.

Clams and Mussels

Vitamin B12 from these shell fishes helps to support brain and nerve function. They are also a good source of iron, potassium and magnesium.

Crab

Zinc and vitamin B12 from crabs will help boost your immunity.

Others:

Honey

Raw honey, besides being sweet golden nectar and a natural sweetener also has anti-viral, anti-fungal and anti-bacterial properties.

Green Tea

Flavonoids from green tea are thought to have anticancer and antioxidant effects in the body.

Water
Although water has zero calories and negligible nutrients it offers many health benefits.


First Published: Wednesday, August 03, 2011, 00:00



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