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PRINCIPLES OF HUMAN NUTRITION II
NTD 302 (2 CREDITS)NUTRITION AND DIETETICS PROGRAMME,
COLLEGE OF HEALTH SCIENCES,
BOWEN UNIVERSITY, IWO
ORONIRAN, OLUYINKA O.
Course Outline • In-depth discussion on foods, their characteristics and effects of anti-nutrients,
•Nutrient interactions and drug-nutrient interactions.
•Bioavailability of Nutrients.
•Dietary guidelines and selection of an adequate diet.
•Recommended dietary and nutrient intakes, safe levels of nutrient intake, balance studies to determine nutrient requirement.
• Basic concept of food and nutrition security.
In-depth discussion on foods, their characteristics and effects of anti-nutrients….
Foods
Why do we have to talk about food?
https://immigrationandhunger.weebly.com/hunger-overview.html
Food is important
Food is essential for life
Food is very important and it is eaten to satisfy hunger
So, We need to understand the importance of food and what it
entails!
LEARNING OBJECTIVES o This module is aimed at:
(i) Discussing in-depth what food is, its characteristics
(ii) Understanding anti-nutrients as a component of food
LEARNING OUTCOMES
o At the end of the module, students should be able to
(i) Explain food as a whole and its importance
(ii) Discuss anti-nutrients and their effects on human health
What then is food?• Food can be said to be a substance that is taken into the body to meet the body’s need for energy, and nutrients for maintenance of life, health, growth, repair of tissues and reproduction.
• It is a substance, either process or raw, solid or liquid form, that is intended for human consumption to provide nutrients that nourishes the body.
• They are basically from plant or animal source, digestible, absorbable, utilizable by the body.
• Food has a shelf life which depends solely on its quality.
•Food, contains not only nutrients but thousands of substances which, for the most part, are considered inert or anti-nutrients.
Remember…(from the introductory course)
Food
Nutrients
Macro-nutrients
Carbohydrate Protein Fat Water
Micro-nutrients
Vitamins Minerals
Non-nutrients
Anti-nutrientsPhytochemical
s Nutraceuticals
Food and its components
Importance of food• Food is very important and it is eaten to satisfy hunger. The basic function of food is to keep one alive and healthy; to grow, develop and be productive.
• Food is essential for life right from the moment the foetus is formed to the end of a being.
• Food is necessary for adequate nutrition hence regular access to food will help eradicate hunger, reduce food insecurity and malnutrition as well.
• Most foods contain more than one nutrient but no single food item supplies all the essential nutrients in the amounts that are needed.
Food nourishes the body for adequate nutrition that is concerned with functional outcomes from the consumption of food which includes
• normal process of growth (foetal and childhood growth),
• cognitive development,
• psychological development,
•maintenance of body tissue,
• ability to perform physical work efficiently,
• reproductive success in women (pregnant and lactating),
• resisting and recovery from diseases and longevity.
Importance of food
Characteristics of food• People decide what to eat, when to eat, and even whether to eat in highly personal ways, often based on behavioral or social motives rather than on an awareness of nutrition's importance to health.
• People choose foods for its taste and the like for certain flavors and sometimes select foods out of habit, which are strongly influenced on food choices are ethnic heritage and tradition.
• The characteristics of food are the several natural substances that occurs which determine the overall quality of food
• (i.e. the set of attributes of food that is acceptable to consumers which includes external factors such as appearance (size, shape, colour, gloss, and consistency), texture, and flavour;
• and internal (chemical, physical, microbial components of a food).
• These substances may refer to the components of food that are termed nutrients which the human body requires to sustain life and maintain health.
• Nutrients are the chemical substances in food that are needed by the body for energy, growth and maintenance, and for maintenance of body processes
• The concentration and amount of these nutrients aids the classification of food groups and classes.
• Food items have been categorized according to nutrient groups to help in the daily use of given types of food.
• The greater the variety of foods, the less likely one can develop a deficiency or an excess of any single nutrient.
• A variety of these nutrients in foods also reduces the likelihood of being exposed to excessive amounts of toxic substances that occur naturally in foods, additives or contaminants that may be present in any single food item.
Characteristics of food
Table showing classes of nutrients for human nutrition
Anti-nutrients and their effects
Anti-nutrients?• There are non-nutrient components of foods that may also determine its quality which includes anti-nutritional factors (anti-nutrients) and phytochemicals.
• Anti-nutritional factors are those components of plants that interfere with metabolic processes and can lead to deficiencies of key nutrients in the diet.
•Anti-nutrients or anti-nutritional factors are compounds or substances which act to reduce nutrient intake, digestion, absorption and utilization and may produce other adverse effects.
• Seeds of legumes, grains and other plant sources contain in their raw state wide varieties of anti-nutrients which are potentially toxic.
• These anti-nutrients pose a major constraint in the use of plant protein sources without adequate and effective processing.
• Anti-nutrients interfere with the assimilation of nutrients thereby affecting the availability of such nutrient for body use.
• Certain plants contain these naturally occurring compounds that are toxic to humans or that reduce the bioavailability of nutrients in foods.
• Examples of foods that contain this anti-nutrient are:• Some species of mushroom that contain toxic compounds, such as agaritine.
• Some cereal-based diets have restricted bioavailability of nutrients as a result of the presence of antinutritional factors such as phytate and tannins or polyphenols.
• Cassava a staple food worldwide has certain bitter varieties that contain high levels of linamarin, a cyanogenic glycoside. The consumption of these varieties has been associated with health defects such as goiter and paralysis of the legs.
•However, food processing methods have evolved that reduce human exposure to both natural toxins and antinutritional compounds.
Anti-nutrients?
Examples of major anti-nutrients These includes:
• toxic amino acids,
• saponins,
• cyanogenic glycosides,
• tannins,
• phytic acid/phytate,
• gossypol,
• oxalates,
• goitrogens,
• lectins (phyto-haemagglutinins),
• protease inhibitors,
• chlorogenic acid
• amylase inhibitors etc.
Tannins• Tannins are condensed polyphenolic compounds widely distributed in plants.
• Plant tannins are present in plant bark, wood, fruits, fruit pods, leaves, roots and plant galls.
•Vegetable tannins are polyphenols with relatively high molecular weight (up to 20,000 Da) and can form complexes with carbohydrates and proteins in aqueous solutions.
•Vegetable tannins are water soluble phenolic compounds that are widely distributed in the plant kingdom.
• Vegetable tannins are further explained to be normal metabolic products and are not the products of in vitro transformation by chemical or other means.
•Tannins are classified into two groups based on the structural types, namely: hydrolysable tannins and non-hydrolysable or condensed tannins.
Tannins•Condensed tannins are abundantly found in higher plants (e.g. proanthocyanidins). These condensed tannins are oligomers, which resist hydrolysis.
•The hydrolysable tannins consist of glucose surrounded by phenolic acids and are readily hydrolyzed by acids, bases and certain enzymes.
•Tannins can produce undesirable effects in food when present in considerably high amounts. Tannins bind with iron, forming compounds that can not be absorbed in the gut.
•They have the ability to form a complex with proteins through hydrogen bonding and covalent linkages. This results in the precipitation of proteins to make it unavailable or reduce their availability for absorption.
•Foods rich in tannins are the seed coat of most legumes, spices, tamarind, turmeric, certain fruits and vegetables, teas, cereal grains such as sorghum, millets, etc.
Oxalates•Oxalate is a common constituent of plants and several species, including some crop plants such as tubers which may either be a cause or a contributor as to the acridity, that can cause irritation, and swelling of mouth and throat
•Oxalates are associated with a decrease in bioavailability of nutritionally significant mineral elements.
•These organic substances can bind essential minerals to form insoluble or indigestible complexes in the lumen of intestinal tracts, thereby preventing their absorption
•Oxalates are found in legumes, grains, vegetables, roots and tubers, etc. It interferes with calcium salts by forming insoluble calcium salts.
•Dietary oxalates can be absorbed and contribute to increased excretion of oxalates in the urine which may predispose the person to oxalate urinary stones.
Phytates/phytic acids•Phytic acid is the storage form of phosphorus that is usually in a bound form called phytate.
•It is considered an anti-nutrient because when bound to other mineral elements like calcium, zinc manganese, iron and magnesium in the digestive tract, it is converted to phytic complexes, which are indigestible substance, making them less available for body uses.
•Phytate is a natural component in plants and on digestion forms insoluble complexes with metal ions in the body. The result is reduced bioavailability of essential minerals such as iron.
• Phytates are hexaphosphate compounds of inositol and are found mostly in cereal grains.
•They bind iron, zinc, calcium and magnesium forming insoluble complexes with iron in the presence of calcium and magnesium hence affecting iron absorption.
Trypsin inhibitors• Trypsin inhibitors are largely found in legumes such as soy. It affects the utilization of protein that is in the food if its not inactivated.
• It is an example of enzyme inhibitors which are polypeptides and proteins that inhibit the activities of digestive enzymes, and most are thermolabile and are reduced by cooking.
• Trypsin inhibitors may cause poor protein digestion and a shortage of sulfur-containing amino acids in the diet.
ASSIGNMENT
Discuss the effects of other anti-nutrients on human health not mentioned above.
