chapter 1 nutrition Flashcards

Question

geneticlly modified food

Answer 1

GeneƟ cally modifi ed foods, also known as geneƟ cally engineered foods or geneƟ cally modifi ed organisms, are foods that have undergone alteraƟ ons to their DNA through the process of geneƟ c engineering. We have been geneƟ - cally modifying organisms for centuries. For example, we preferenƟ ally breed certain organisms with other ones in order to get desirable traits in their off spring. That is how we get seedless grapes and watermelons as well as diff erent colours of carrots. To be clear, the consumpƟ on of geneƟ cally modifi ed food does not change our own geneƟ cs. The plant or animal’s geneƟ cs are slightly altered, but that does not get incorporated into our own DNA

Answer 2

GeneƟ cally engineered crops may also involve the use of a vector to implant desirable traits into an organism (Figure 1.5). This is typically done to improve the growth of that food, make it more resilient to environmental threats or to boost its nutriƟ onal quality. For example, geneƟ c engineering has produced plants that are resistant to herbicides, a type of rice (Golden Rice) that is higher in vitamin A and papaya plants that are resistant to the highly destrucƟ ve ringspot virus. InteresƟ ngly, this last intervenƟ on is believed to have maintained the papaya industry in Hawaii where ringspot threatened to bankrupt it (Stokstad, 2008). There are many other foods that are geneƟ cally modifi ed, such as so-called cash crops. Cash crops are those that are heavily produced, sold and traded, such as corn and soy. Soy alone accounts for about half of all commercially available geneƟ cally modifi ed foods worldwide (James, 2014)

Answer 3

Food addiƟ ves are substances added to food for the purpose of taste, appearance, safety, freshness or other factors. There is a wide range of food addiƟ ves, including preserving agents like sodium nitrate, thickening agents like guar gum and sweeteners like high-fructose corn syrup. For any of these substances to be approved for use in food processing, their safety must be evaluated. For instance, the Food and Agriculture OrganizaƟ on/WHO Joint Expert CommiƩ ee on Food AddiƟ ves (JECFA) evaluates the safety of food addiƟ ves that are traded internaƟ onally (World Health OrganizaƟ on, 2018a). During their review process, an examinaƟ on of all scienƟ fi c evidence is performed. The short-term and long-term eff ects, including any potenƟ al for harm are evaluated. If an addiƟ ve is approved, there is typically a recommendaƟ on for the maximum amount that can be added to food. This amount will be below the threshold for harm, if there is one. Food addiƟ ves are typically found in processed and ultra-processed foods. Anyone concerned about the eff ects food addiƟ ves might have on health can easily minimize them by consuming more unprocessed NOVA group 1 foods.

Answer 4

body structure , body function , energy , pleasure ,

Answer 5

The study of body structure is called anatomy. Nutrients contribute to our anatomy in various ways. Except for vitamins, nutrients can be found within most body cells. For instance, cell membranes are made up of lipids. Proteins and carbohydrates can be found embedded within these membranes. The inner goo, or cytoplasm, of a cell is made up of water and certain minerals like potassium and chloride are found within it. Figure 1.6: Food promotes body structure and funcƟ on and supplies energy to meet our needs. The body is 60–70% water by weight, most of which provides structure to cells. Protein also adds structure to our muscles, bones and teeth. Minerals harden our bones and teeth, making them stronger. Lipids provide body structure and cushioning when they are stored in adipose Ɵ ssue. Together, these nutrients make the body structure capable of performing its many funcƟ ons.

Answer 6

The study of body funcƟ ons is called physiology. At any given moment, the body is in the process of accomplishing millions of physiological tasks that keep us alive and help us respond to our needs. All nutrients contribute to physiology by being involved in various reacƟ ons and processes aimed at maintaining homeostasis. Homeostasis is a state of dynamic equilibrium that allows our bodies to funcƟ on opƟ mally.

Answer 7

The body needs energy in order perform its various funcƟ ons and keep us alive. This is known as basal metabolism. In addiƟ on, the body needs energy to be able to perform the various acƟ viƟ es we do throughout the day. The more acƟ ve an individual is, the more energy they require. Furthermore, we use energy to help process the food we eat and to make heat. Only three nutrients provide energy to the body. Carbohydrates, lipids and proteins are the energy-yielding nutrients, providing 4, 9 and 4 kilocalories (Box 1.1) per gram, respecƟ vely. Alcohol also provides energy (7 kcal per gram), but it is a drug, not a nutrient

Answer 8

A calorie is the unit used to measure food energy in Canada. It is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius. 1 kilocalorie is equivalent to 1000 calories. We generally use the term Calorie (note: with a capital C) to denote a kilocalorie. So, when we say there are 300 Calories in a food, we mean there are 300 kilocalories or 300 000 calories in it.

Answer 9

Diet is one of the main factors that aff ects our health and risk for disease. In the short term, what we eat from day to day can aff ect our energy levels and how our body feels. In the long term, what we regularly eat can aff ect our risk for developing certain diseases. In fact, of the major causes of death in Canada,

Answer 10

Modifi able risk factors include whether a person smokes, is inacƟ ve or experiences a high degree of stress in their life. Unmodifi able risk factors include gender, age and geneƟ cs.

Answer 11

GeneƟ cs and diet have an interesƟ ng relaƟ onship. Our geneƟ c makeup can infl uence our appeƟ te, the availability of nutrients, how those nutrients are used and their eff ects on the body as well as how we taste and experience food. For instance, certain people have a geneƟ c predisposiƟ on to certain diseases, one that an unhealthy diet can exacerbate. Neither our geneƟ cs nor diet can fully predict whether we will develop a disease or not, but they can each aff ect our disease risk. While we cannot change our DNA, we can change our daily food decisions. Th

Answer 12

Though diet cannot change the sequence of DNA we inherently have in our cells, it can aff ect the way genes are expressed – that is, whether a segment of DNA will be coded into a funcƟ onal protein. The study of this interacƟ on is called nutriƟ onal epigeneƟ cs. NutriƟ onal epigeneƟ cs explores how the foods we eat can change DNA expression, even if the DNA code stays the same. This seems to be especially true during early life. For instance, a pregnant mother’s food consumpƟ on can aff ect what genes are expressed and the risk for disease in her future child (Vickers, 2014). An example of this phenomenon has been studied in a mouse model called the agouƟ mouse

Answer 13

AgouƟ mice have an altered version of the agouƟ gene. This geneƟ c change causes the mouse to have both a yellow coat colour and obesity. Researchers fed pregnant agouƟ mice either a normal diet or one that was rich in something called methyl groups. The liƩ er of mice from the mother who was fed the normal diet were like their mother – yellow, obese and prone to disease. However, the pregnant mice that were fed the methyl-rich diet produced a liƩ er that was more brown, lean and not prone to disease. All other factors between the mice were the same – the only thing that changed was the mother’s diet. Methyl groups do not alter DNA codes, but they alter whether DNA can be expressed or not. A small change in the mother’s diet led to a change in

Answer 14

balance , moderation , variety , nutrient desnity

Answer 15

Dietary balance means to have things in the right proporƟ ons. This applies to the nutrients and energy we consume but also to the general choices we make. For instance, having too much of one nutrient and not enough of another or consuming too much energy and not expending enough can both aff ect health. Balance can also refer to the healthy and less healthy decisions we make. For instance, in our society it is diffi cult for many people to consume strictly unprocessed foods from NOVA group 1 in Figure 1.3, even though they most promote health. However, if most of the food we consume comes from the ultra-processed food group, this can have negaƟ ve health consequences. Balance means fi nding the right equilibrium between these types of food. Balance does not mean 50/50 – it means fi nding the right proporƟ ons of the things that help us achieve a parƟ cular result, in this case health. A good rule of thumb when it comes to nutriƟ on is 80/20. This means that 80% of our nutriƟ onal decisions should be ones that promote health, while 20% can be less healthy (Figure 1.11).

Answer 16

Dietary variety means consuming a diversity of foods (Figure 1.12). No single food can provide all the nutrients in the right proporƟ ons: some foods are high in some nutrients, while others are high in other nutrients. The greater variety of foods we consume, the less likely we are to develop symptoms of defi ciency. Defi ciencies are more common in people who avoid groups of foods or have a less-varied diet.

Answer 17

ModeraƟ on means not too much and not too liƩ le. In other words, it ensures that our diets are adequate, so we do not develop nutriƟ onal defi ciencies, but not excessive to the point where they promote complicaƟ ons. For instance, consuming insuffi cient sodium can negaƟ vely aff ect our body’s ability to send electrical signals. Conversely, too much sodium increases cardiovascular risk in some people. The concept of moderaƟ on also applies to the amount of energy we take in. If we do not take in enough energy, we may feel Ɵ red and have a harder Ɵ me accomplishing our daily acƟ viƟ es. Conversely, if we regularly overconsume energy, this puts us at a higher risk for obesity, type 2 diabetes and cardiovascular disease.

Answer 18

Nutrient density refers to the amount of nutrients in a food or meal as compared to a reference amount. Typically, a 100 kcal reference amount of food is used. Figure 1.13 compares the nutrient density of a cola beverage to 2% milk. In this example, we see that in 100 kcal of milk we have a high quanƟ ty and variety of nutrients. In comparison, 100 kcal of cola provides mostly sugar.

Answer 19

The science of ranking foods based on nutrient density is called nutrient profi ling. There are several ways in which this is done, but the focus of these techniques is to diff erenƟ ate between foods that are high in essenƟ al nutrients, like protein and vitamins, and lower in nutrients that may increase risk of disease when consumed excessively, like trans fat (Drewnowski et al., 2019). In general, whole foods tend to be more nutrient dense than processed and ultra-processed foods. Consuming more of these NOVA group 1 foods and less of the group 3 and 4 foods, can increase the nutrient density and healthfulness of our diets.

Answer 20

NutriƟ on is the study of the foods we eat and their eff ects on us and our environment. I

Answer 21

Epidemiological and experimental research are the two main methods used to study nutriƟ on. Each has strengths and weaknesses.

Answer 22

Experimental studies are oŌ en called randomized control trials. They are the gold standard for making inferences from research. This is because they control all variables, except for the one factor that is being studied. For instance, to test whether a certain dietary supplement improved alertness, two idenƟ cal groups where everything was executed the same way would be needed; the only diff erence being that one group would consume the supplement while the other would not. Using this controlled procedure means that when an eff ect is seen aŌ er a study, it is most likely due to that one variable that was changed. For instance, if the group receiving the dietary supplement had signifi - cantly higher levels of perceived alertness, we would aƩ ribute that aff ect to the supplement, as everything else was the same between groups. In this example, the group receiving the dietary supplement is the experimental group, while the one that didn’t receive the supplement that was used for comparison purposes is the control group. To reduce the risk of intenƟ onal or unintenƟ onal bias that could aff ect the results, control groups are oŌ en given a placebo. For instance, the control group may be given a fake supplement – a sugar pill that has no eff ect on the body. A well-conducted experiment involving humans will have

Answer 23

hese are outlined in Figure 1.15. However, there are very few, if any, studies that fi t all these criteria. Typically, the more checks on this list, the beƩ er the study is, and the more credible the results. For instance, a well-designed experiment may be blind, or beƩ er yet, double-blind. A blind study means that neither the experimental nor control group knows which group they are in. They just know what the experiment is about and that they might receive an acƟ ve treatment or a placebo. This lowers the chance for bias and any psychological or unintenƟ onal eff ect that could aff ect the parƟ cipants’ behaviours and the study’s results. A double-blind study is one where neither the scienƟ sts nor the subjects know which group is receiving the experimental treatment and which is receiving the placebo. This reduces the chance for bias from the experimenters as well. While experimental studies are best at establishing causality, human nutriƟ on studies are diffi cult to perform and have several limitaƟ ons. For one, it is diffi cult to force a person do something. Also, some people may drop out of a study or not follow the instrucƟ ons given by the researchers. Further, we

Answer 24

Because human nutriƟ on experiments are diffi cult, Ɵ me-consuming, costly and someƟ mes unethical to conduct, an epidemiological design is typically used to study nutriƟ on. Epidemiological studies, also known as populaƟ on-based studies, look at trends in populaƟ ons without manipulaƟ ng any variables. For instance, instead of asking a populaƟ on to consume a diet high in fi bre, as we might do in an experimental study, in an epidemiological study we may look at populaƟ ons that already consume a high fi bre diet and compare them to those that do not. A good example of this type of research is the Nurses’ Health Study, a series of studies that started in 1976 and followed nurses forward through Ɵ me (Colditz et al., 2016). The researchers gathered informaƟ on about these nurses including their dietary paƩ erns as well as other health-related metrics such as whether they smoke, exercise or have a family history of disease. Over Ɵ me, some of these nurses developed heart disease, cancer and other diseases or died. Since the researchers had a lot of informaƟ on about these nurses’ habits, history and health, they could then look at whether there were certain habits or condiƟ ons that were more common in the groups that developed disease or died prematurely. For instance, one of the most notable outcomes of this study was that women who had higher intakes of saturated fat were more likely to develop cardiovascular disease. The same was found in an epidemiological study of men called the Health Professionals Follow-up Study (Zong et al., 2016). Both studies followed a prospecƟ ve epidemiological design, where a large, similar group is followed forward through Ɵ me.A criƟ cal point to understand about epidemiological studies is that associaƟ on does not equal causaƟ on. For instance, just because a link was found between two factors (i.e., saturated fat and cardiovascular disease) it does not mean one leads to the other (i.e., high saturated fat intake leads to cardiovascular disease). In epidemiological studies, we cannot control all the variables that may infl uence disease. For instance, perhaps women who eat a high saturated fat diet are also more likely to have other lifestyle factors that increase their risk of CVD; perhaps it is not the saturated fat in the foods they consume that increases their risk, but the foods they ate that are high in saturated fat; perhaps the way we collected informaƟ on about their dietary habits misrepresented them. For all these reasons and more, it is important to not look at epidemiological evidence alone, and instead combine it with what has been found in other studies that used diff erent research methods. This is what makes nutriƟ on confusing for a lot of people. We may read one headline that says one thing, but another that says something else. A good way to think about it is that each study is a certain piece of the puzzle, but none can show the full picture alone. Another major weakness of epidemiological studies is the lack of accuracy in determining a populaƟ on’s diet. For instance, how do we accurately gauge the quality and quanƟ ty of a person’s diet? Table 1.1 provides an overview of the typical ways diet is assessed in these studies, including their strengths and potenƟ al limitaƟ on

Answer 25

Biochemistry, molecular biology and computer modelling techniques can also be used to study nutriƟ on using the scienƟ fi c method. While these add to our knowledge base, they cannot always account for the complex interacƟ ons between foods, diets and the human body.

Answer 26

Evidence is a body of facts and informaƟ on that helps us determine whether something is true or valid. This textbook, as well as all nutriƟ on-focused journal arƟ cles, primarily use experimental and epidemiological evidence to assess the eff ects of nutriƟ on on health. These scienƟ fi c methods and results, however, are rarely highlighted on the internet and in social media. Anecdotal evidence is what is typically used to sell products and sway opinions. Anecdotes are personal tesƟ monies drawn from direct or indirect casual experiences. For instance, an Instagram post may feature an infl uencer selling a weight loss supplement with a before and aŌ er photo staƟ ng how well the supplement worked for them. But beware – just because someone says something worked for them it doesn’t mean it is safe and will work for someone else. Many infl uencers are paid to sell products that they do not even use (Figure 1.16). In Canada, infl uencers must disclose whether an ad is sponsored. Look for the hashtags #ad, #sponsored, #XYZ_ambassador, #XYZ_ partner to know if the person has been paid to post an ad (Ad Standards Canada, 2019). This shows that they may be biased and not providing credible informaƟ on. Furthermore, just because someone provides an anecdote that something worked for them or someone they know, it does not mean it is safe, eff ecƟ ve, sustainable or backed by good science. While anecdotal evidence is emoƟ onally convincing and parƟ cularly eff ecƟ ve in adverƟ sements, it can be deceiving and potenƟ ally harmful to health if we follow the wrong guidance.

Answer 27

So far, we have explored the process of collecƟ ng data through experimental and epidemiological studies. CollecƟ ng data is important, but it is also imperaƟ ve that this data is analyzed properly and thoroughly evaluated, and that accurate conclusions are drawn. This typically takes the work of a skilled research team whose work is further reviewed and assessed through a process called peer review. Before a scienƟ fi c arƟ cle can be published, it must be reviewed by experts in the fi eld who were not involved in the study process to make sure the study was properly conducted, the results were properly analyzed, and conclusions were properly drawn. Many arƟ cles found on the internet have not undergone peer review and are more likely to be misleading or false.

Answer 28

ollowing the peer-review process, if an arƟ cle summarizing a nutriƟ onal study is accepted, it will be published in a research journal. Some journals have a higher threshold for the quality of studies and results that they will publish. A journal’s impact factor is a way of determining its importance and rank based on how many Ɵ mes its arƟ cles have been cited by other researchers. Pubmed (Figure 1.17) is an excellent search engine that can be used to search for peer-reviewed journal arƟ cles about nutriƟ on and human health as well as a wide range of health-related topics. Google Scholar and a university library search engine can also be used to fi nd scienƟ fi c arƟ cles

Answer 29

While scienƟ fi c journal arƟ cles are the gold standard of credible sources, they typically require a knowledge of science and scienƟ fi c terminology to be understood. Primary journal arƟ cles, those that summarize a scienƟ fi c study, are oŌ en highly specifi c and it may be challenging to fi nd more general answers. That said, the introducƟ on secƟ on of many arƟ cles typically gives a broader overview of the topic before the specifi c study is outlined. Review arƟ cles may be more helpful for general quesƟ ons, as they oŌ en summarize diff erent studies to give a broader sense of a phenomenon. We can use the word “review” in our search criteria in addiƟ on to topic keywords to search for these types of arƟ cles. A review arƟ cle that can be helpful for broader perspecƟ ves is a systemaƟ c review. SystemaƟ c reviews involve a panel of topic experts reviewing a wide range of primary research studies and evaluaƟ ng the strength of evidence to support or not support a phenomenon. SomeƟ mes, new analyses and staƟ sƟ cal tools are applied within a systemaƟ c review to come to new staƟ sƟ cal conclusions. This is called a meta-analysis. Figure 1.18 outlines the hierarchy of evidence credibility and illustrates what informaƟ on is more likely to properly represent the evidence. This textbook will primarily use systemaƟ c reviews to support statements that are made. SomeƟ mes, other review arƟ cles or primary research, such as randomized control trials and epidemiological studies, may also be used to highlight a poin

Answer 30

Two-eyed seeing is the pracƟ ce of equally using both a Western science lens as well as an Indigenous ways of knowing lens to help us understand things. TradiƟ onally, schools have employed only a Western science lens, but this is changing. For example, the BriƟ sh Columbia and Ontario school boards both recommend that teachers broaden students’ understanding of the natural world by bringing in Indigenous culture, knowledge and voices in addiƟ on to its scienƟ fi c study. There are some signifi cant diff erences between these two lenses. For instance, in Western science we oŌ en reduce food to its nutrient content and then study the eff ects of individual nutrients on the body. We see food as a non-living thing that we take from the earth for our own benefi t. Conversely, tradiƟ onal and modern Indigenous cultures typically see food as a dynamic, living enƟ ty, one that forms part of our relaƟ onship with each other and the land. They may give to their food system as much or more than they take from it. For this reason, Indigenous food systems and relaƟ onships are being studied by many Western scienƟ sts, as they are oŌ en seen to be more holisƟ c, healthy and environmentally sustainable than our current food systems. It is important to note that there is not one Indigenous culture or viewpoint in Canada and there is much diversity in their pracƟ ces, locaƟ ons, urbanizaƟ on and occupaƟ ons. Indigenous Peoples are oŌ en categorized according to three main groups found in the land known as Canada: the First NaƟ ons, Inuit and MéƟ s. Within these groups there are diff erent tribes, each with their own concerns and perspecƟ ves. Unfortunately, colonizaƟ on silenced many of these Indigenous perspecƟ ves. However, there is now more interest than ever to understand and voice them. While this textbook is wriƩ en by a non-Indigenous person, eff orts have been taken to properly represent Indigenous perspecƟ ves with respect to many nutriƟ on topics. Whenever possible, Indigenous voices are used to represent the variety of beliefs, pracƟ ces and consideraƟ ons of the many Indigenous people. The intent is to improve our two-eyed seeing; to use a diff erent lens alongside our Western views of nutriƟ on, thus painƟ ng a more holisƟ c picture.