Archive for category: Biology

“Nutrition Facts” Food labels:

Read the information provided below, then answer all of the questions at the end of this Assignment. Total points: 8.

Use the numbered lecture/lab notes below for information needed in order to answer each numbered question at the end and titled: Assignment Questions. Lab Manual #17: Diet Analysis, Exercise #3 is an additional source of information, Quality ‘Google’ searches can of course also provide additional information.

 

#1. “Nutrition Facts” Food labels: How many of you are used to checking labels when you shop at the grocery store? There are over 35,000 different types of foods that can be found in the average large grocery store. Many of these items have a label stating: Nutrition Facts. You are to pick two different labels, and provide the information asked for in Question #1 at the end of these notes. Here are some helpful tips:

Be sure to realize the serving size & # servings per container – – [for example: a beverage can state 120 calories per serving, but the entire container could be 3 servings, therefore 360 calories!]

Total fat: food labels are required to list the percent of the food which is lipid/fat, & a further breakdown as to what % of fat is saturated fats & trans fats. These two subcategories of fats increase the risk of forming atherosclerosis: atherosclerosis is a leading cause of heart attacks & strokes; it is a slow buildup of fatty deposits & LDL cholesterol, along with blood clotting factors, reducing blood flow in arteries. [trans fats used to be quite common until it was realized how much they increase the risk of atherosclerosis – – only recently has % trans fats been required to be included on food labels, & through this awareness fortunately trans fats are often 0% now]. Cholesterol is also usually listed. It is not normally considered to be a major factor relative to the two other fats mentioned above. One reason for this is that the liver in your body also produces cholesterol, & in many people is able to adjust amount produced depending on amount taken in in the diet.

Sodium: The average American consumes an excess of sodium. It is estimated that 500mg/day is enough for the average adult (check the mg levels on the food label). Excess sodium intake can be an issue particularly with people who have hypertension or heart disease. Eating excess sodium leads to excess sodium in the bloodstream which draws water by osmosis from other areas of the body, into the bloodstream. So, what then would happen to blood volume? increase. What would happen then to blood pressure? increase. What is the pump which would have to work harder because of this increased blood pressure? The heart.

Total Carbohydrates: Note the breakdown into dietary fiber, & sugar. Fiber/cellulose is a form of carbohydrate that cannot be absorbed into the body because we do not have the digestive enzymes to break it down into monomers. OK, so the calories related to the % listed on the label, aren’t calories you will take in! Fiber also helps keep food flowing at a ‘regular’ pace (not too fast or slow – -many people take fiber supplements to help with maintaining regular bowel movements). Sugars: if the percent for sugars is high, it can lead to an issue related to ’empty calories’: calories without any additional nutrients. [For example, if you check the food label for the average soda drink, the vast majority of calories come from sugar. It is estimated that the average high school student in America consumes at least 3 sugary beverages per day]. Excess sugar not only increases the risk of obesity, but is also an issue with diabetics & people with pre-diabetes which an estimated 1 in 5 Americans are at risk of.

Protein: There are different forms of protein: incomplete compared with complete protein; you will learn more about this in #2 of this assignment. The amount of protein needed per day for the average adult is ~40 -55 grams. Of course that varies depending on weight, muscle mass, exercise/activity, etc. Some body builders require more that 3 times that level.

Vitamins/Minerals: Depending on the product, a variety of different vitamins & minerals may be listed. Realize that with many of these, the body has the ability to ‘store’ that particular vitamin/mineral in case it is not in the diet for a period of time – – that period of time though varies greatly [fat soluble vitamins – A, E, D, K can be stored in fat reserves for several days+; iron is readily stored in reserves unless there is excess blood loss, – – & an excess of iron supplements can actually be toxic (free radical if >5x U.S. RDA); some B vitamins have storage capabilities of weeks, but a few less so – especially under certain circumstances with high demand (example: all pregnant women are prescribed vitamin B12 supplements); etc.!]

Ingredients: Realize that the ingredients are listed in order from those in highest amount (by weight), to those in smallest amount. Any ingredient listed in parentheses means that it is part of the ingredient listed right before the parentheses, & is also in order of amount. Here are some additional things to look for: “enriched flour”: this happened back in the 1970s to help ensure there were enough vitamins in processed flour. [‘white’ grains usually mean they have been processed, & so many of the nutrients that would normally be in the outer parts of the grains have been removed; this is as opposed to ‘whole grains’ whole wheat flour, etc.] Also check for preservatives: you want to avoid excesses of things like: nitrates/nitrites (there are options nowadays for hot dogs, bacon etc which say on the label: nitrate/nitrite free!), sodium benzoate, artificial colors, BHA, BHT; these are all potential carcinogens/mutagens if ingested on a regular basis.

#2: Proteins: There are “complete” proteins, & “incomplete” proteins. Complete proteins contain all of the essential amino acids needed by humans. There are 20 different types of amino acids used by all living organisms. 8 of these 20 are essential to humans, which means that we are not able to synthesize or interconvert these particular amino acids, & so therefore need a continual supply from our diet. Any of the other 12 amino acids – so long as we ingest at least one of them – can be interconverted into any of the other 12. Realize that any protein in our body is comprised of several thousand amino acids, so every protein in our body will need all 20 amino acids. Realize also that there is continual metabolism of molecules in our body, including proteins; they are formed, broken down into amino acids, & then reformed depending on each cell’s needs. If a cell is missing even one essential amino acid, protein synthesis will be compromised [even within a day or so]. There are no protein ‘storage depots’ in our body, so if we lack protein in our diet, our body will start breaking down body muscle (this includes all 3 types of muscle: cardiac, skeletal, & smooth).

So, we need a continual supply of complete proteins. Examples of complete proteins are: any animal foods (poultry, beef, eggs, cheese, milk ..). If a person is a vegan, then finding complete protein sources is harder, but can be done through mixing different protein sources: rice & beans, corn & beans, etc. & there are some vegetarian complete proteins: many nuts, tofu or other soybean sources, quinoa, lentils,

#3. Additional information regarding carbohydrates: There is approximately one day’s supply of carbohydrates stored as glycogen, primarily in liver & muscle. If a person lacks carbohydrates & sugar in the diet, then alternate energy reserves must be used via proteins & lipids. As you learned in #2 there are not really body protein reserves, body muscle would have to be used. But there is up to 2 month’s (!) energy reserve in lipids as adipose tissue located throughout your body. If lipids are used as the primary energy source, be it from diet or adipose reserves, a toxic byproduct can build up as a result of converting too many lipids into ATP energy. That toxic byproduct is? Ketones. If you have heard of the ketogenic diet, it is one in which a person eats very little if any carbohydrate/sugar. This diet can be a stress on the body due to buildup of ketones, & needs to be monitored by a physician if someone severely reduces carbohydrate/sugar intake.

An additional note regarding lipids: there are essential fatty acids: (you can’t leave out all fats from your diet!): think back to the term essential amino acids; the same applies here. Examples are: linoleic & linolenic acid, Omega 3 & 9 fatty acids.

 

#4: Find and list one major function of your choice for each of the following: four different vitamins, & four different minerals. Do a Google search to find this information.

#5: Here’s an additional hint to help in answering Assignment question #5 below: as you can see from working on the above questions, a well-balanced diet is the goal. So, have the right balance of carbohydrates, proteins, lipids, vitamins, & minerals in your diet.

 

Assignment Questions:

#1. Choose two different Nutrition Facts labels you saved from two different grocery store items. You may want to choose one from a food that you think is healthy, & one from a food you think is not as healthy nutritionally. Then, for each one: list parts of the food label you think are important; include additional comments regarding the different sections of the food label as related to the information from the lecture notes above. Did each food label turn out to be better or worse nutritionally than you originally thought?

#2. Given the information you have read above (& also can be from reputable key word search), in your own words define the terms: complete protein, and essential amino acid. Which sources of protein normally have all essential amino acids: animal or plant? How can you compensate for this if your main food source is vegetarian? What would be the main problem/body response to not having enough complete protein in your diet (reminder notes above)?

#3. Define ketones, and how they relate to a diet insufficient in carbohydrates/sugars. Are ketones safe at high levels (ie relying on fat stores for calories)?

#4. List one major function for each of: 4 vitamins, 4 minerals: so a total of eight.

#5. Imagine: if you were suddenly on a deserted island, & could only bring 5 different foods from the grocery store to survive on for a week, as healthy as possible, which 5 would you choose? Assume there is drinkable water on the island, but not refrigeration/freezer. Explain why you chose those 5 items.