Introduction: Nutrition and Disease

RELATIONSHIP BETWEEN DISEASE AND NUTRITION

the role of nutrition in disease prevention

Nutrients are the raw materials that support physiologic and metabolic functions needed for maintenance of normal cellular activity.

Incase of inadequate nutrient intake there will be Malfunctioning of cellular activities due to an inadequate level of support from available nutrients.

This will be initially expressed in biochemical changes that will eventually develop into clinical symptoms characteristic of the particular roles of the nutrients involved.

Example inadequate intake of iron will eventually develop into clinical signs such as paleness of the eyes, tongue and nails

However the nutrient deficiencies may develop because of inadequate intake, impaired absorption, increased demand, or increased excretion.

Sometimes nutrients also interact negatively with each other, Excessive intakes of some nutrients may promote deficiencies of others through impaired absorption, increased demand, or increased excretion.

Example iron will require a protein carrier

Fat soluble vitamins will require a fat media in order for them to be absorbed

Iron and zinc compete for the same transport pathway

Functions of nutrients in the body for both nourishment and pharmacological functions

They are involved in energy production, release and storage e.g fat and carbohydrates are used in energy production, vitamins especially B vitamins are used in release of energy and storage

Building of lean body mass and skeletal mass e.g proteins build the lean body mass, calcium, phosphorus and vitamin D are responsible for skeletal mass

Regulatory functions such as enzyme activation like proteins, gene production -zinc is involved

Synthesis of bioactive compounds such as hormones, enzymes, immune substances

Fluid, electrolytes and acid base balance is maintained in a well nourished individual. When someone has deficiency of some nutrients the above balance of offset.

Potassium and sodium balance will affect the fluid and electrolyte balance

Pharmacological functions of nutrients in the body

Antioxidant activity- e.g vitamin E, selenium, vitamin C

Detoxification- e.g water

Phytochemicals such as group B vegetables which contain isoflavonoids

Nutrients with Nourishment and Pharmacologic Functions

• Nutrients that support immune function-zinc, vitamin C, protein, vitamin A, vitamin B6, Folate
• Nutrients that provide antioxidant protection-vitamin C, carotenoids, vitamin E, selenium
• Nutrients that support synthesis of enzymes and bioactive compounds-amino acids, vitamin B6, fatty acids, selenium
• Nutrients involved in tissue synthesis-protein, energy, zinc, vitamin A, vitamin C, iron

Both excess and deficient nutrient intakes may contribute to development of chronic degenerative diseases.

These diseases can be considered an expression of cumulative cellular damage due to environmental assaults for which the threshold of exposure at which damage is incurred is defined by genetics.

Imbalances in dietary patterns are among the environmental factors that contribute to the development of chronic diseases.

Either diet may be directly involved in the pathogenesis of the disease or it may exacerbate pathological changes due to other environmental factors.

The goals of nutrition in prevention of disease are:

• To optimize cellular activity and tissue/organ function
• Provide sufficient amounts to satisfy daily demands of adequacy, balance and variety in food choices
• Maintain adequate reserves for intermittent increased demand through habitual diet and dietary patterns
• To reduce the metabolic burden imposed on cardiac, pulmonary, renal, hepatic, and musculoskeletal systems by environmental factors
• Minimize workload of organ systems by reducing stress on organs involved in transport, metabolism and elimination of nutrients and metabolic waste.
• Eliminate compensatory responses required to maintain normal function
• To support cellular defenses that protect tissue integrity
• Maintain immune system competence
• Promote efficiency of detoxification systems by controlling levels of reactive chemical intermediates
• Prevent oxidative damage that is involved in pathogenesis of most chronic diseases and reduction of efficiency of immune cells

Nutrition and the immune system

Overview of the immune system

The immune system is the collective army of a trillion white blood cells, bone marrow, antibodies, cytokines and the thymus gland that help to identify and destroy the millions of microbes (i.e. bacteria, viruses, parasites, fungi) that penetrate our bodies every day, and the thousands of our own cells that have become genetically abnormal or cancerous.

It involves various cells and lymphoid organs which are classified as central (primary) and peripheral or secondary lymphoid organs

Central (primary) include-

Bone marrow where we have the B and T lymphocytes originates and B lymphocytes matures

Thymus cells where T lymphocytes matures

Peripheral or secondary lymphoid organs

lymph nodes

spleen

gut associated lymphoid tissues such as tonsils, appendix

The immune system comprises of different type of cells such as lymphocytes, granulocytes and monocytes

NB/ B and T lymphocytes are the major player in the immune system

Other Central Organs of the Immune System

Skin

• Creates Physical barrier
• Glands secrete chemicals that can destroy microbes

Mucous Membranes

• Mucous contains chemicals and enzymes that destroy invading organisms
• Traps microbes

GI Tract

• Stomach acid destroys microbes
• Villi along lining keep invaders out

The role of the Immune system in the body

• Protects the body from infectious agents and toxins
• Enables the body to repair damaged cells
• Rids the body of worn out cells

How the Immune System Works

• White blood cells, phagocytes and lymphocytes (natural killer cells, T-cells, B-cells) destroy antigens
• Phagocytes - engulf antigens
• Lymphocytes - work on specific antigens (may release chemicals that destroy antigen or produce antibodies that mark cells for destruction)

How does immune system strength determine health?

The strength of our immune system determines our body's ability to resist infection and the growth of abnormal (cancerous) cells. If it is below its optimum level, we are much more prone to illness, both from infections and cancers.

If our immune system is maintained at optimum level, our incidence of disease is less, and we are less likely to develop abnormal cell growths. Also, when we do become ill or have a physical injury, a healthy immune system can ensure the fastest possible recovery. In some serious cases, for example with cancer, immune system strength can literally mean the difference between life and death. Without a healthy immune system, the body and mind languish in a state of ill health, greatly prolonging the journey back to vitality.

A good indicator of the level of our immune system is how energized or alive we feel. If we feel low or weak, our immune system is probably low and weak. A strong immune system not only determines how healthy our bodies are, but our mental state as well. It is of fundamental importance to both body and mind, therefore, for everyone to maintain optimum immune system health.

Nutrition and the Immune System

• Malnutrition weakens immune system
• First line of defence (skin, mucous, cells of GI tract) break-down allowing more antigens to invade inside the body
• Insufficient protein intake decreases immune cell number-When T-cell number decreases regulatory T-cells decrease immune response is delayed
• Obesity affects the body's defence system-Responses of T-cells and B-cells to antigens may be reduced
• Diets that are high in fat seem to depress the immune response and thus increase the risk of infections- Type of fat consumed can affect the immune system, also total amount and type of fat in the diet affects immune system
• For example, Omega-6 fatty acids can suppress immune response, alter inflammatory response,May increase risk of asthma on the other hand Omega-3 fatty acids - decrease inflammation, increase immune response and limits tissue damage
• Regular consumption of fermented dairy products such as yoghurt or kefir may enhance the immune defences in the gut. Recent research results suggest that yoghurts made with certain bacteria (called probiotics) may have a beneficial effect on the immune system.

Role of specific Nutrients on the immune system

Vitamin A - needed to make healthy skin, mucous and lymphocytes; deficiency can alter response of antibodies to antigens and cytokine responses. Studies in Third-World countries have shown that the administration of Vitamin A to malnourished children confers protection against measles and reduces the death rate associated with this viral infection. The administration of Vitamin A to cortisone-treated animals appears to abolish the immunosuppressive effects of cortisone. Vitamin A enhances white blood cell function, enhances resistance to infection and carcinogens, and helps maintain skin and mucus membrane defenses to infection. Carotenoids and beta-carotene has antioxidant properties that can help in cancer prevention.

• Vitamin C - may decrease duration of virus symptoms
• Zinc - T-cell production, lymphocyte responses, resistance to infections

B cpmplexes- It can lead to decreased white blood cell response and shrinkage of the critical immune system organ, the thymus.

• B12 is also central to immune processes because it governs cell division and growth. Without adequate B12, white blood cells can't mature and multiply. Folic acid also plays a key role in immune system development and maintenance.
• Vitamin B6 - antibody production, lymphocyte responses

Vitamin c: is an immune system booster par excellence. White blood cells use Vitamin C to combat infections, and in the face of inflammation or microbial challenge, levels of Vitamin C are depleted. Animals have the ability to manufacture extra Vitamin C in their livers to replete their stores -- but humans lack the crucial enzyme that synthesizes C. Thus, when confronted by stress, we need additional outside sources of C.

• Vitamin E - needed for phagocytosis, antibody production, lymphocyte responses

Chromium: Mostly thought of as a blood sugar regulatory mineral, recent research in animal models shows chromium can enhance the ability of white blood cells to respond to infection.

Copper: Affects the human immune system by reducing the activity of some cells that attack invading bacteria. .

Iron: The immune system keeps invading microbes in check by depriving them of iron via a specific immune defense substance called lactoferrin, made in the intestine and found in mothers' milk.

Manganese: Enhance natural killer cell and macrophage activity.

Selenium: protect humans from the heart-damaging effects of cytomegalovirus (CMV). Selenium deficiency may allow viruses to mutate into more dangerous pathogens.

Other non-vitamin mineral supplements may have a role in supporting immunity. Here are some of the key players:

Arginine: The amino acid l-arginine augments T-cell response and may be helpful in hastening surgical recovery, as well as in cancer and AIDS.

lysine, an amino acid which keeps certain viruses in check. e.g herpes virus common in HIV and AIDS patient

Disease symptoms with nutritional implication

Fever- this leads to increased metabolic rates. Increase od body temperature by 10c leads to increased nutrient requirements by 10%

Diarrhea

Lack of appetite

Vomiting