Nutrition and Health

Nutrition and Health

Nutrition and health • The importance of nutrition in the primary prevention of disease has long been recognised in the public sector. • The influence of food intake on health and wellbeing has drawn many research interests and continues to develop.

Good Food v.s. Bad Food? • A food that is beneficial to the body is regarded as a Functional Food, in that, it is one claiming to have additional benefits other than nutritional value. • Foods may also contain substances that are harmful to health, these are regarded as Naturally Occurring Toxicants.

Functional foods • There are two different types of claim that are specific for functional foods: • Type A – relates to a positive contribution to health or to a condition linked to health, to the improvement of a function or to modifying or preserving health. • Type B – relates to the consumption of a food that might help reduce the risk of a specific disease or condition.

1. Cholesterol lowering functional foods • Dietary Fibre – has been shown to play an important role in cholesterol metabolism by decreasing plasma cholesterol and low-density lipoprotein cholesterol (LDL-C) levels. • In general, most soluble fibres lower plasma cholesterol more efficiently than water insoluble fibres by decreasing LDL cholesterol without significantly affecting the HDL-C and triaclyglycerol levels.

Water soluble fibres • peas • soybeans • broccoli • carrots • sweet potatoes • onions Water insoluble fibres • whole grains • corn • bran • wheat • flax seeds • cabbage

Phytosterols – are cholesterol-like molecules found in all plant foods, with the highest concentrations found in vegetable oil. • They function to inhibit the absorption of intestinal cholesterol, a key step in lowering plasma cholesterol. • It has been suggested that the daily intake of 2g of phytosterols can effectively lower the cholesterol by 9-14% in humans with little or no effect on HDL-C and triacylglycerol levels (Law, 2000).

Tea catechins – are a group of antioxidant plant metabolites found predominately in green tea. • Epidemiological observations indicate that tea consumption is associated with reduced levels of plasma cholesterol and LDL-C. • In addition, the consumption of 375mg of tea theaflavin a day effectively reduced cholesterol and LDL-C in mild and moderate hypercholesterolemia subjects.

Soya proteins – the Food and Drug Administration (FDA) suggested that incorporating soya proteins in a diet low in saturates and cholesterowering cholesterol levels. • In 2002, the UK Joint Health Claims Initiative (JHCI) approved the health claim on the association between soya protein and cholesterol reduction. • The inclusion of at least 25g of soya protein per day, as part of a diet low in saturated fat can help reduce blood cholesterol levels.

2. Obesity management with functional food • Obesity arises from an energy imbalance whereby energy intake exceeds energy expenditure. • Dealing with obesity requires modification of one or both components of energy balance. Energy Output Energy Input

Energy intake – one promising avenue to reduce energy intake using functional foods is through increased satiety. • The goal is to provide foods that increase the sense of fullness and encourage the individual to stop eating sooner, thereby reducing total energy intake. • High protein diets are currently popular for weight loss and are based on the idea that high-protein diets promote satiety.

Energy expenditure – Recently, it has been demonstrated that diets high in calcium maybe protective against weight gain and that part of the mechanism maybe an increase in energy expenditure. • Oolong tea is another food that may have some impact on increasing energy expenditure, perhaps by its catechin content. • In a study by Rumper et al 2001, it was reported that resting metabolic rate has increased by 3-4% during three days of oolong tea consumption at 5 cups per day.

Energy storage – if some of the energy ingested is not absorbed completely, this can reduce net energy available to meet metabolic demands and can lead to weight loss. • Olestra is a non-absorbable fat substitute that has been shown to reduce energy intake. Olestra was approved by the FDA in 1996 for use in savoury snack products. • Olibra, which is a 95.5% mixture of fractional palm oil and oat oil, has been reported to inhibit appetite.

3. Diabetes and functional foods • Diabetes mellitus is a disease in which the body cannot regulate the amount of sugar in the blood. There are two types of diabetes: • Type 1 diabetes is when the pancreas stops or produces too little insulin, a hormone that regulates blood sugar levels. • Type 2 diabetes is when the pancreas produces insulin, but the body is partially or completely unresponsive to react to the insulin.

Pumpkins – a study carried out in China revealed that a compound found in Asian pumpkins acted to regenerate damaged pancreatic cells amongst rats with diabetes. This may suggest that the increased insulin levels may reduce the need for insulin injections or other diabetes management drugs.

Bitter melon (karela) – a study has isolated four compounds in bitter melon and revealed that these compounds may activate an enzyme that is responsible for regulating metabolism and transporting glucose from the blood into the cells. • The bitter melon extract may be useful in treating diabetes by helping the body to digest sugar molecules in the blood, thereby lowering blood sugar.

Naturally occurring toxicants • Naturally occurring toxicants may cause toxic effects within hours, days or weeks of consumption of food, or they may have mutagenic or carcinogenic effects in which an inheritable change in the genetic information of a cell may lead to cancer or other disease states over a period of time.

Diarrhoatic shellfish poisoning (DSP) – belongs to the marine toxin group. It has been reported throughout the world, with most incidents recognised in Europe and Japan. • Diarrhoea, nausea, vomiting and abdominal pain occur within 30 minutes to a few hours of consumption of contaminated shellfish and last for up to 3 days. • Bioaccumulation occurs commonly in mussels, clams and scallops, which concentrate DSP toxins.

Paralytic shellfish poisoning (PSP) – is also a marine toxin. It is caused by the consumption of contaminated bivalve molluscs (i.e. clams, cockles, mussels). • The onset of illness occurs within 15 minutes to 10 hours after consumption. Symptoms vary depending on the toxin involved and the amount ingested, which includes paralysis of the mouth, throat and extremities, dizziness and muscular and respiratory paralysis.

Vitamins and minerals • Vitamins are organic compounds that cannot be synthesised in the body and so it is required in small amounts from the diet. • Minerals are elements other than carbon, hydrogen, oxygen and nitrogen that are found in the body. Both vitamins and minerals are essential in the diet in small quantities and so they are often grouped together as micronutrients.

Vitamin A • Alsoknown as retinol plays an important role in vision, bone growth and reproduction. It also functions to regulate the immune system, which helps prevent or fight off infections. • Rich sources of vitamin A comes from beef liver, some dairy products (i.e. milk, cheese and butter), oily fish (i.e. tuna and sardines) and colourful vegetables (i.e. carrots, spinach, apricots, papaya and yellow squash).

Vitamin A Requirements • Diets low in fat intake can result in vitamin A deficiency, especially in children between the ages of 1 – 5 years. • People living in developing countries are also at risk due to the lack of dietary diversity and the prevalent infectious intestinal disease. • To prevent vitamin A deficiency, a diverse diet is recommended.

Vitamin B1 • Also known as thiamin plays an important role in carbohydrate metabolism by converting glucose into the usable energy in the body. It also stimulates action in the brain and promotes general growth. • Main sources of thiamine can be found in unrefined cereals and rice, legumes, apricots, melons and many leafy vegetables.

Vitamin B1 Requirements • Thiamin deficiency is common in chronic binge drinking alcoholics (particularly in those with liver disease). • Thiamin deficiency is also found in those undergoing renal dialysis.

Vitamin B2 • Alsoknown as riboflavin, helps to metabolise fat, protein and carbohydrate. It also helps to create red blood cells and antibodies and is especially important during periods of rapid growth as with young children and babies. • Rich sources of riboflavin can be found in cow’s milk, as well as some fruits such as papaya, apples, currants and apricots. It can also be found in some nuts and whole grains, especially almonds and walnuts.

Vitamin B2 Requirements • For pregnant and lactating women and infants, riboflavin requirements are higher. • This is because concentrations of riboflavin in breast milk is lower than in cows milk. • Riboflavin supplementations maybe required.

Vitamin C • Also known as ascorbate acid is required for the growth and repair of tissues in the body. • Vitamin C is one of many antioxidants, nutrients that block the damage caused by free radicals. Free radicals are by-products produced in the body during the transformation of food into energy. The build up of these by-products over time is largely responsible for the ageing process and can contribute to the development of various health conditions such as cancer and heart disease. • All fruits and vegetables contain some amounts of vitamin C. Foods that contain the highest sources of vitamin C include green pepper, Brussels sprouts, broccoli, citrus fruits and juices, strawberries, cranberries, blueberries, papaya and mango.

Vitamin C Requirements • In order to meet increased foetal demands, pregnant woman are recommended to increase their vitamin C intake. • Vitamin C concentration in lactating women should also increase vitamin intake in order to maintain sufficient levels in breast milk.

Vitamin D • Is essential for the promotion of calcium absorption in the gut and so is needed for adequate bone growth. • Without sufficient levels of vitamin D, bones can become brittle and thin. In addition, vitamin D also helps to promote the immune system and the reduction of inflammation. • Very few foods in nature contain vitamin D. the flesh of oily fish such as salmon, tuna and mackerel and fish liver oils are among the best sources. • Small amounts of vitamin D can also be found in beef liver, cheese and egg yolks. Most people, however, meet their vitamin D needs through exposure to sunlight.

Vitamin D Requirements • Elderly people are at higher risk of vitamin D deficiency. As people age, the skin cannot synthesize vitamin D efficiently and so its requirements are made higher. • People with limited sun exposure are also at risk of vitamin D deficiency. • It is suggested that at risk groups should increase their sunlight exposure. Fish oil supplements may also be recommended.

Vitamin E • Is also an important antioxidant that helps to reduce the damage caused by free radicals. • This may help to prevent or limit the chronic diseases associated with free radicals. • In addition, vitamin E is involved in immune function and other metabolic processes. • Numerous foods provide vitamin E. Nuts, seeds, and vegetable oils are among the best sources, and significant amounts are available in green leafy vegetables and fortified cereals.

Vitamin E Requirements • Patients with heart disease and lung cancer are at high risk for vitamin E deficiency. • This is due to the fact the tobacco smoke is rich in free radicals, which leads to the depletion of vitamin E.

Iron • Almosttwo-thirds of iron in the body is found in hemoglobin, the protein in red blood cells that carries oxygen to tissues. • Smaller amounts of iron are found in myoglobin, a protein that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. • A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity. • Iron can be derived from red meats, fish and poultry. Iron can also be found in plants such as lentils and beans.

Calcium • Is one of the most important minerals for growth, maintenance and reproduction. It helps to form and maintain healthy teeth and bones. • In addition, calcium helps with blood clotting, nerve signalling, muscle contraction and the release of certain hormones. It is also needed for a normal heartbeat. • Dairy products are the most significant sources of calcium, such as yoghurt, cheese and buttermilk. Other sources come from broccoli, turnip greens and other green leafy vegetables.

Zinc • Is needed for the body’s defensive system. It plays a role in cell division, cell growth and wound healing. • It is also needed for senses of smell and taste. • Rich sources of zinc can be found in high protein foods such as beef, pork and lamb. The dark meat of chicken contains more zinc than light meat. Peanuts and legumes are also good sources of zinc.

Magnesium • Plays an important role in muscle contraction and relaxation. It also promotes the function of certain enzymes in the body. • Most dietary magnesium comes from green leafy vegetables. Other good sources include bananas, apricots, avocadoes, legumes and nuts.

Nutrition and Health