The digestive system and food safety principles

Nutrition-Health-Science

The Digestive System

Mechanical digestion begins the process of digestion. Otherwise known as chewing, it "involves mixing, grinding, or crushing large pieces of food into small pieces" (Lab: Mechanical and chemical digestion, n.d, Chapter 38). In contrast, the process of chemical digestion occurs inside of the body within the digestive organs, "when digestive enzymes break down complex molecules, such as carbohydrates, into simple molecules, such as glucose" (Lab: Mechanical and chemical digestion, n.d, Chapter 38). When digesting a ham and cheese sandwich, first the teeth grind the sandwich mechanically. Then this is followed by the process of breaking down the food chemically within the body. While mechanical digestion is a willed activity in the sense we select the foods we eat and how much we chew, chemical digestion is not.

During the process of chemical digestion, "the parietal cells of the stomach produce HCl and secrete it primarily in response to ingested protein or fat" (in the cheese and the ham) and protect the stomach against harmful bacteria that might have entered the body during food preparation or consumption (Haas 2012). After the food leaves the stomach, "the small intestine carries out most of the digestive process, absorbing almost all of the nutrients you get from foods into your bloodstream. The walls of the small intestine make digestive juices, or enzymes, that work together with enzymes from the liver and pancreas to do this" (Organs: Large and small intestines, 2013, Children's Hospital of Pittsburgh). By the time the food reaches the large intestine, it consists mainly of dead cells and fiber. 'Helpful' bacteria in the large intestine "feed on this mixture. These helpful bacteria produce valuable vitamins that are absorbed into your blood, and they also help digest fiber" (Organs: Large and small intestines, 2013, Children's Hospital of Pittsburgh).

Q2. Food Safety & Technology

Technology such as refrigeration and preserving has vastly improved the ability of human beings to eat a wider variety of foods safely, year 'round. "Yeasts, moulds and bacteria" are the primary causes of food spoilage (Causes of the spoilage of food, n.d., Food Preservation). As well as being unpleasant to look at and taste in most forms, spoilage and contamination can cause illness in humans. The core principles of food safety include proper hygiene (hand-washing, wearing protective gloves, not working while ill); keeping food at the proper temperature through heating or refrigeration; by cooking food until done (keeping food out of the danger zone of bacterial growth of 140-41F); and avoiding cross-contamination (such as not using the same knife to cut raw poultry and vegetables for example) (The basic principles of food safety, 2006, NH Department of Health & Human Services).

Eating organic food does not mean that one automatically is eating food that is safe. However, according to the USDA, "organic produce and other ingredients are grown without the use of pesticides, synthetic fertilizers, sewage sludge, genetically modified organisms, or ionizing radiation. Animals that produce meat, poultry, eggs, and dairy products do not take antibiotics or growth hormones… Organic-certified operations must have an organic system plan and records that verify compliance with that plan" (Organic FAQ, 2013, Organic.org). Organic food can still be contaminated with pathogens, but there are other health risks many consumers want to avoid association with the consumption of pesticides and antibiotics.

Q4.Nutrition & Physical Activity

Most people are aware of the benefits of physical activity as a source of calorie burn. Exercise improves heart health by elevating good (high-density lipoprotein) cholesterol and decreasing unhealthy triglycerides or 'bad' cholesterol (Exercise, 2013, Mayo Clinic). It improves lung function, reduces high blood pressure, contributes to regular digestion, and generally improves all aspects of physical functioning. By building muscle, it increases strength and can protect against bone breaks and fractures. It also increases bone density. It improves mood functions by boosting 'feel good' neurotransmitters in the brain and can be an important component of stress reduction, as well as give a feeling of empowerment to the exerciser. It can provide a source of social engagement and accomplishment.

Q5. Lipids

"Fat provides a more concentrated source of energy than carbohydrate or protein (providing 9 calories per gram vs. 4 calories per gram)" (Barke 2005). This is why fat often has a reputation as a 'bad' nutrient, but it is vitally necessary to human health and survival. As well as satisfying caloric needs, fat plays a vital role in the ability of the body to absorb nutrients. "Fat is required to transport vitamins A, D, E and K, produce hormones, store energy, maintain healthy skin, and protect organs" (Facts about fat, 2010, McKinley Health Center). Consuming unsaturated vs. saturated fats actually lowers rather than elevated 'bad' blood cholesterol. Up to 20-25% of the diet can come from fats, ideally from healthy sources such as vegetable oils, avocados, and nuts and seeds rather than primarily from saturated sources in the form of animal proteins which elevate the 'bad' cholesterol levels (Barke 2005).

Q6.Proteins

Proteins are often called the 'building blocks' of the body and are essential for the construction of immune cells, skin cells, blood cells, and muscle cells (Barke 2005). Proteins are made up of essential amino acids in the form of carbon, hydrogen, and oxygen atoms and a nitrogen (amino) group (Why you need protein in your diet, 2012, For Dummies). Maintaining adequate skin, muscle tissue, bone, red blood cells, and creating new cells all requires protein. Even the neurotransmitters of the brain require protein to function. In general, approximately 15-20% of total calories of the diet should be composed of proteins (Barke 2005). 'More' protein is not necessarily better, contrary to what some athletes believe -- it can put a strain on the body's kidneys and result in the inadequate consumption of other vital nutrients required for daily functioning (Barke 2005).