Chapter Minerals and Water © 2012 Pearson Education, Inc Why Is Water So Important? Water is the most abundant substance in body Average healthy adult is about 60 percent water Muscle: 65 percent water, fat: 10 to 40 percent water Age and body composition influence the % of water in the body We can only survive a few days without water Nutrition and You, 2e © 2012 Pearson Education, Inc Your Body is Mostly Water Figure 8.1 Nutrition and You, 2e © 2012 Pearson Education, Inc Body Water Balance Water is balanced among fluid compartments Intracellular fluids: inside cells (60-75% of body water) Extracellular fluids: interstitial fluid between cells and fluid in the blood (25-40% of body water) Electrolytes: minerals that help maintain fluid balance Nutrition and You, 2e © 2012 Pearson Education, Inc Water as Part of Body Fluids Figure 8.2 Nutrition and You, 2e © 2012 Pearson Education, Inc Functions of Body Water Acts as universal solvent and a transport medium Medium for many chemical reactions in body As part of blood, helps transport oxygen, nutrients, hormones to cells As part of interstitial fluid (between cells), helps transport waste products away from cells for excretion Helps maintain body temperature Is a lubricant for joints, eyes, and is part of mucus and saliva Is a protective cushion for brain, organs, fetus Nutrition and You, 2e © 2012 Pearson Education, Inc Water Helps Regulate Your Body Temperature Figure 8.3 Nutrition and You, 2e © 2012 Pearson Education, Inc Maintaining Water Balance Water balance: water consumed = water lost We take in water through beverages and food We lose water through the kidneys (as urine), large intestine, lungs, and skin (as sweat) Insensible water loss: through evaporation from skin and when we exhale Nutrition and You, 2e © 2012 Pearson Education, Inc The Concept of Water Balance: Intake Equals Output Figure 8.4 Nutrition and You, 2e © 2012 Pearson Education, Inc Water Content of Foods Figure 8.7 Nutrition and You, 2e © 2012 Pearson Education, Inc Iron Sources and Physical Needs Food Source Iron Nutrition and You, 2e © 2012 Pearson Education, Inc What if we don’t get enough iron? Iron deficiency is the most common nutritional deficiency in the world Risk groups: Women during the childbearing years Anyone in a growth stage Early signs and symptoms include weakness, tiredness, poor attention span, poor appetite, increased susceptibility to infection Iron deficiency anemia occurs when hemoglobin levels decrease Nutrition and You, 2e © 2012 Pearson Education, Inc Healthy Red Blood Cells Nutrition and You, 2e © 2012 Pearson Education, Inc Anemic Red Blood Cells Nutrition and You, 2e © 2012 Pearson Education, Inc Iron Overload/Iron Toxicity Too much iron from supplements can cause constipation, nausea, vomiting, diarrhea Leading cause of accidental poisoning deaths in children under years Iron overload can damage heart, kidneys, liver, nervous system Hemochromatosis, a genetic disorder of excess iron absorption can cause iron overload Nutrition and You, 2e © 2012 Pearson Education, Inc Zinc Acts as a cofactor for more than 100 enzymes Functions: DNA synthesis, growth, and development Healthy immune system and wound healing Taste acuity May reduce risk of age-related macular degeneration Daily needs: Men: 11 mg/day; women: mg/day Vegetarians may need as much as 50 percent more Nutrition and You, 2e © 2012 Pearson Education, Inc Zinc Food sources: Red meat, some seafood, whole grains Too much or too little: UL = 40 mg/day As little as 50 mg can cause stomach pains, nausea, vomiting, diarrhea 60 mg/day can inhibit copper absorption Excessive amounts can suppress immune system, lower HDL cholesterol Deficiency: hair loss, impaired taste, loss of appetite, diarrhea, delayed sexual maturation, impotence, skin rashes, impaired growth Nutrition and You, 2e © 2012 Pearson Education, Inc Zinc Sources and Physical Needs Food Source Zinc Nutrition and You, 2e © 2012 Pearson Education, Inc Fluoride Functions: Strengthens tooth enamel against dental caries Helps repair enamel eroded by acids from bacteria Reduces amount of acid bacteria produce Strengthens bones Fluoridated drinking water has reduced dental caries in United States Daily needs: Men: 3.8 mg/day; women: 3.1 mg/day Nutrition and You, 2e © 2012 Pearson Education, Inc Fluoride Sources: Foods are not a good source Fluoridated drinking water and beverages made with this water Too much or too little: Too little increases risk of dental caries Too much can cause fluorosis (mottling/staining) when teeth are forming during infancy/childhood Fluorosis of bones can occur when >10 mg/day is consumed for 10 or more years UL adults = 10 mg/day, much lower for infants and children Nutrition and You, 2e © 2012 Pearson Education, Inc Iodine Needed to make essential thyroid hormones Thyroid hormones regulate metabolic rate; help heart, nerves, muscle and intestines function properly Daily needs: adults: 150 µg/day Food sources: Salt-water fish and seafood Iodized salt Amount in foods depends on iodine content of soil, water, fertilizer Nutrition and You, 2e © 2012 Pearson Education, Inc Iodine Too much or too little: UL = 1,100 µg/day Excess iodine can impair thyroid function, decrease synthesis and release of thyroid hormones Early sign of deficiency = goiter (enlarged thyroid gland) Mandatory iodization of salt has decreased iodine deficiency in United States but not in other parts of world Iodine deficiency during early stages of fetal development can cause cretinism (congenital hypothyroidism) Nutrition and You, 2e © 2012 Pearson Education, Inc Iodine Sources and Physical Needs Food Source Iodine Nutrition and You, 2e © 2012 Pearson Education, Inc Table 8.2.1 Nutrition and You, 2e © 2012 Pearson Education, Inc Table 8.2.2 Nutrition and You, 2e © 2012 Pearson Education, Inc [...]... Your Daily Water Needs Figure 8. 8 Nutrition and You, 2e © 2012 Pearson Education, Inc Think Before You Drink: Can Water Boost Your Brain? Nutrition and You, 2e © 2012 Pearson Education, Inc Benefits of An Adequate Water Intake Decreased risk of Kidney stone formation Bladder cancer Colon cancer Breast cancer? Nutrition and You, 2e © 2012 Pearson Education, Inc Signs of Adequate Water Intake... magnesium and zinc Form the mineral comes in Heme versus non-heme iron Competition with other minerals Excess zinc can interfere with copper absorption Body’s need for the mineral Nutrition and You, 2e © 2012 Pearson Education, Inc Classification of Minerals Major minerals (macrominerals): needed in amounts >100 µg/day Trace minerals (microminerals): needed in amounts