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NFS284 Chapter 10, 11, 12 Lecture Notes

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Nutritional Science
Tom Wolever

NFS284 Chapter 10, 11, 12 – Minerals Slide 1 Minerals are inorganic. Slide 4 Hyponatremia is that too much water dilutes the sodium in our system. This is a result of excessive sweating during prolonged exercise because we lose salt in our sweat. If you just replace the water and don’t replace the salt, you dilute the sodium in the blood, which changes the osmotic pressures. Slide 5 Most Canadians consume above the UL of sodium. Slide 6 Potassium has an AI. Potassium doesn’t have an EAR. It is interpreted differently than an AI. We can conclude that many Canadians are not consuming at the level of the AI. Slide 7 In less processed foods, it is mostly potassium and barely any sodium. Sodium is not naturally occurring. In more processed foods, the ratios start to change. The same amount of potassium is present, but there is even more sodium. What is the impact of high sodium diets against low potassium diets or against high potassium diets? How do these ratios affect our health (e.g., blood pressure). Slide 8 K+ sits on the inside of the cell. Na+ sits on the outside of the cell. Slide 9 When the kidney senses the increase in blood pressure, then the kidney down regulates the whole system. Slide 10 Salt sensitivity is that some people can’t tolerate salt without having their blood pressure go up. Slide 11 Doubts about restricting salt are misinformation. Slide 12 The concern is that you can go too low. UL = 2300 mg. AI = 1500 mg. When they looked at risk of CVD, they didn’t find much benefit from going from 2300 mg to 1500 mg. This means that for the general population, if they can get their sodium down to 2300 mg, then that is probably low enough. They don’t have to go lower than 2300 mg. There is evidence that it is potentially harmful to go down too low. There is no controversy that that the “average sodium intake” is too high. The issue is once we get everyone down to the 1500 mg to 2300 mg range, should we be advising them to go even lower or is that good enough? Slide 13 At lot of research looking at if the background of a high potassium diet can mitigate the effect of some of the sodium intake. There is an interaction between these two minerals in the body. Salt makes food taste food. Salt acts as a flavour enhancer because it is able to bring out other flavours in food. Salt is the cheapest ingredient that a food processor can put into the food to make it taste good. Slide 14 A) Whole grain carrot orange muffin = 470 mg B) Small bowl of chili = 1180 mg C) Big Mac = 1020 mg D) Chipotle chicken snack wrap = 680 mg E) Garden veggie pizza slice = 1110 mg F) Pepperoni pizza slice = 1600 mg Slide 15 A) Banana = 422 mg B) Orange juice = 486 mg C) Baked potato = 926 mg Slide 16 White vegetables are being overlooked. White vegetables have nutritional value. There is more emphasis on coloured vegetables. Slide 17 Gestational hypertension can develop into pre-eclampsia. Slide 18 Potassium, calcium, and magnesium are believed counterbalances the effect of sodium. Slide 20 The trace minerals are just as physiologically important as major minerals. Slide 21 You need all of the four food groups to get a good intake of all of the required minerals. Slide 23 Sodium absorption is 100%. Iron and calcium absorption is low. Iron and calcium tend to form insoluble salts in the gut, so they tend to be eliminated because the mineral has to be soluble in order for it to get into the cell and get into the blood stream. Slide 24 There is a high prevalence of inadequate intake of calcium. Slide 25 The numbers improve a little bit if you include both food and supplements. If you are not consuming enough calcium, the body will take calcium from the bones to maintain a certain level of blood calcium. Slide 27 Minerals act as cofactors with enzymes, which renders the enzyme active. Slide 29 You can absorb some calcium passively, but it helps to have a calcium transport protein, which requires vitamin D. Slide 30 Calcium is not absorbed very efficiently because calcium tends to form an insoluble complex. Tannins, fibre, phytates, and oxalates complex with calcium and reduce calcium absorption. Slide 31 Bone acts as a reservoir for calcium. Slide 33 [Spongy bone?] is metabolically active. [This?] is where the calcium comes from if it needs to go into the blood to support calcium blood levels. [This?] gets porous as bones age. Collagen (organic) is the scaffolding on which the hydroxyapatite crystal (inorganic) deposits. Slide 34 Bone is metabolically active. Depending on the strains and stresses that we put our bone under (e.g., childhood, adulthood, daily life), there is a constant remodelling of our bones. Bone formation requires osteoblast (b = builds bone). Osteoclasts consume bone, which is required to breakdown/reshape the bone when we respond to stresses. Osteoclasts secrete acids that dissolve the mineral component of the bone. As we get older, osteoblast activity tends to decline and osteoclast activity tends to continue. As we age, there is a net loss of bone. This will result in osteoporosis. Slide 35 Osteomalacia, which is a result of vitamin D deficiency, is the loss of the mineral component of bone. Osteopenia is low bone density. Slide 39 Osteoporosis occurs in two sites: the hip and the spine. One side of the vertebrae is cortical bone (strong) and the other side is trabecular bone (spongy). The spine is beginning to curve. There is a decline in height. When the spine is collapsed and the body is scrunched forward, then the lungs are being compressed. The internal organs in the torso get compressed. This makes people vulnerable to respiratory infections. Slide 41 As we grow, we absorb more calcium into our bones. Eventually, in men and women, we stop growing, and our accretion of calcium declines. Peak bone mass happens around age 30. Men tend to achieve a higher peak bone mass than women because they have bigger bones. After age 30, this is where the osteoblast activity begins to decline. You see a general decline in bone mass. In men, it is a steady decline. In women, around age 50 (menopause), there is a dramatic decline in bon
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