Dietary policy Flashcards
Nutritional status
Nutrional status is the condion of the body with respect to nutrion. It helps us determine whether a person has the appropriate level of nutrients to meet their needs. There is no single complete measure of nutrional status. However, the following methods may be used alone or in combinaon with each other to help inform it.
Dietary analysis
A dietary analysis typically involves three main steps:
1. Recording everything a person ate for a period.
2. Comparing recorded intake levels to specific recommendaons.
3. Determining whether the person’s nutrient status is adequate, deficient or excessive.
Historically, this process was labour intensive. First, consumed foods were recorded manually. Then, the nutrient profile of each food was found in a database. Finally, the total nutrient intake per day was compared to reference values.
Acurate diet analysis
To get an accurate diet analysis, we must be as specific as possible with respect to the amounts and types of foods we eat. We also need to be careful with the effect feedback can have on our food intake. The awareness of what and how much we are eang may cause us to change our behaviour. While this feedback can be an effecve behaviour change tool, it compromises the accuracy of a dietary analysis meant to assess current nutrional status., This process can now be done more simply with a wide range of both free and commercial diet analysis soware (Figure 2.1). This soware is linked to a nutrients database that has the reference values for each nutrient embedded in its algorithm. People simply enter their daily food intake and the soware does most of the work.
Lab tests
A dietary analysis can give insight into whether our nutrient intake meets our needs, but it fails to account for what happens in the body when we eat food. We do not all digest, absorb and use nutrients the same way. Laboratory tests use blood samples to determine nutrional status. For instance, a test called a blood lipid panel looks at the lev- els of certain lipid-based compounds in the body to see if they are within a healthy range (Figure 2.2). Having values of blood lipids outside of a healthy range can be associated with an increased risk of cardiovascular disease. If unhealthy levels are found, dietary modificaon can then be used to get levels into ranges that decrease disease risk.
Health and disease
When assessing nutrional status, another consideraon is a person’s health or disease state. Dietary recom- mendaons are made for healthy people, but if someone has a specific health consideraon, these recommendaons may have to shi. For instance, hemochromatosis is a condion where iron builds up in the body due, in part, to an in- crease in absorpon. If we simply assess the diet of someone with hemochromatosis without considering their condion, we might make recommendaons that promote excessively high iron levels. This could have serious complicaons, such as an increased risk of liver and heart disease.
Dietary references intake
The dietary reference intakes (DRIs) are a set of scienfically determined reference values for nutrient require- ments. They tell us how much of a nutrient is required to meet the needs of an individual. These requirements vary depending on gender and stage of life. For example, compared to midlife, the daily requirement for calcium is higher in adolescence and older age. Also, from age 51–70, women have a higher calcium need than men. This is due, in part, to the hormonal changes of menopause that affect bone health. DRIs have a margin of safety, so it is unnecessary to hit the recommended value exactly in order to meet needs. At the individual level, they can be used to assess nutrional status and determine whether an individual is inadequate, adequate or excessive for a nutrient (Figure 2.3). At the populaon level, they can be used to inform dietary recommendaons. Canada and the USA use the same four DRIs.
Estimated average requirement
esmated average requirement (EAR) is the amount of a nutrient that will meet the needs of 5o0% of the populaon. For example, the EAR for calcium for those aged 19–50 is 800 mg/day. If everyone consumed that amount, approximately half of all people would be adequate for calcium, while the other half would be deficient. Accordingly, the EARisrarelyusedasastandaloneDoRI.Itsmainroleistohelpsettherecommendeddietaryallowance
Recommend dietary allowance
The recommended dietary allowance (RDA) is the amount of a nutrient that meets the needs of 97% of the pop- ulaon. The RDA is set at two standard deviaons, about 20–25%, higher than the EAR. For example, the RDA for calcium for those aged 19–50 is 1000 mg/day, 25% higher than the EAR of 800 mg/day. If we cannot determine the EAR, then an RDA cannot be set. The RDA is the preferred DRI for determining adequacy. If everyone consumed this amount, only 3% of the populaon would be at risk for deficiency.
Adequate intake
Somemes, there is not enough scienfic data to establish the EAR and RDA. In such cases, an adequate intake (AI) value is used. The AI is typically determined by observing how much of that nutrient healthy people eat. Since these individuals do not show signs of deficiency, it is assumed that this amount is adequate for most healthy people. Com- pared to the EAR and RDA, less evidence is used to establish an AI. Therefore, it is more difficult to establish deficiencies using the AI alone (Instute of Medicine, 2000).
Tolerable upper limit
Unlike the other DRIs, the tolerable upper limit (TUL), or upper limit (UL) is focused on excess. If we consume an amount of nutrient in excess of its UL, we are more likely to show signs of toxicity. For instance, the UL for calcium for those aged 19–50 is 2500 mg/day. Intakes above this may increase risk for calcium toxicity, which can promote the calci- ficaon or hardening of the organs. Noce that the TUL for calcium is 2.5 mes higher than the RDA. There is typically a large range between the RDA/AI and the UL. Accordingly, there is a range of intake amounts that are adequate, but not excessive.
Energy recommendation
The DRIs can help assess nutrional status with respect to the micronutrients and macronutrients. However, they do not provide recommendaons with respect to energy intake. Energy intake recommendaons come in two main forms. The esmated energy requirement esmates the total amount of energy needed to maintain a person’s current size. In contrast, the acceptable macronutrient distribuon range gives recommendaons for the percentage of energy to come from each of the three energy-yielding nutrients.
Estimated energy requirements
Energy needs vary by person. To maintain energy balance, energy intake and energy expenditure need to match. When a person is consistently at energy balance, their weight remains fairly constant. If we are trying to gain energy and weight, we would consume energy in excess of the esmated energy requirement (EER). Alternavely, if we are trying to lose energy and weight, energy intake levels would need to be consistently below the EER. If our goal is to maintain our current weight, on average, our daily energy intake should be close to our EER.
How much daily energy is required to maintain energy balance depends on sex, age, height, weight and acvity levels. The best way to assess this is through certain laboratory approaches. Energy expenditure can also be esmated using the EER calculaon (Figure 2.4a). This equaon requires that we esmate our average acvity levels, as energy re- quirements fluctuate depending on how much we move our bodies. Figure 2.4b lists the physical acvity coefficients for the EER calculaon and what they signify.
Acceptable macronutrient distribution range
The acceptable macronutrient distribuon range (AMDR, Table 2.1) outlines the recommended percentage of energy that should come from each of the three energy-yielding nutrients: carbohydrates, lipids and proteins. There is no RDA for lipids and carbohydrates, so the AMDR can be used to determine whether intake meets health needs. Protein has both an RDA (0.8 g/kg body weight) and an AMDR. To assess adequacy, both may be considered. These ranges have been set based on epidemiological data that suggests consumpon within these levels is associated with reduced risk for chronic disease.
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Dietary guidelines
The DRIs are useful for an in-depth dietary analysis that is focused on finding nutrient deficiencies and excesses. However, they are not very praccal for daily use. This is where dietary guidelines come in. Many countries put out food guides to simplify nutrion recommendaons and help us make healthy dietary decisions.
Canada food guide
Canada was one of the first countries to have a food guide. Canada’s Official Food Rules (Figure 2.5) were developed and distributed during the Second World War to help prevent nutrional deficiencies, while also acknowledging the need for food raoning (Health Canada, 2002). As the Cana- dian diet, food landscape and nutrion science have evolved, so too have our food guides. Other versions of Canada’s Food Guide included a recommended eang paern for breakfast, lunch and dinner (1949) as well as the four food groups concept of the 1970s and 1980s.
43, In 2013, Health Canada started the process of revamping many food policies. Canada’s Healthy Eang Strategy’s main objecve was to make healthy eang easier for Canadians. One major change was an overhaul of the Canadian food guide (Health Canada, 2016b), whose previous iteraon came out in 2007. The intent was to align recommenda- ons with the current evidence and dietary paerns of Canadians and to improve how dietary messages are communi- cated (Health Canada, 2016a). A range of stakeholders including nutrion and health experts were consulted to refine the recommendaons and the way they were presented. The newest Canadian food guide was released in early 2019 (Figure 2.6). It has since been translated into many languages, including several Indigenous languages to reflect the diver- sity of Canadians.
Plate portion
main feature of the guide is that it is now illustrated as a plate with recommended food proporons:
50% of the plate is vegetables and fruits. Note that the word vegetable comes before the word fruit. This is
meant to communicate the foundaonal role of these plants in the diet.
25% of the plate is whole grains. These foods are the staples in many diets and the guide communicates the importance of consuming unrefined versions of them.
25% of the plate is protein-rich foods. While protein can be found in all secons of the plate, the foods in this quadrant are especially high in protein. These protein-rich opons are of both animal and plant origin, so both vegetarians and omnivores can build a healthy plate that fits their lifestyle.
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Key themes im plate guide
The guide also has several key themes:
* Variety. The plate has a wide range of foods in each secon.
* Accessibility. The plate features foods that are relavely inexpensive for most people.
* Cultural relevance. Given the diversity of the Canadian populaon, there are foods that are key staples to many ethnic diets, such as rice and beans.
* Availability. The guide features opons that are available at mes of year in different forms, either fresh, frozen, canned or dried.
Veggies and fruits
Vegetables and fruits (Figure 2.7) are a good source of fiObre, vitamins and minerals. Large-scale epide- miological studies have repeatedly found that diets high in vegetables and fruits are associated with a reduced
risk of diseases such as heart disease and cancer (Alissa & Ferns, 2017; Riboli & Norat, 2003). The food guide recom- mends consuming whole vegetables and fruits over juices and concentrates, which tend to be processed and high
in added sugar. Fresh, frozen and canned vegetables are recommended as healthy opons, especially those with no added sodium, sugars or seasonings. Healthier cooking opons such as baking, roasng, steaming and sr-frying are recommended, as is flavour enhancement with olive oil, lemon juice, flavoured vinegar and herbs and spices.
Praccal suggesons for increasing vegetable and fruit intake include pre-chopping and refrigerang vegetables and fruits or buying them pre-chopped so that they are easy to grab and use. Also, cucumbers, grape tomatoes and peppers can be easily served raw as an addion to a meal. Further, trying recipes with different leafy greens such as kale, spinach and bok choy can be helpful.