Importance of Water in the Body

Water - Main Constituent of the Body

• A healthy man(170 pounds) is composed of 62% water, 16% protein, 16% fat, 6% minerals, and <1% glycogen
• A healthy woman(130 pounds) is composed of 57% water, 13% protein, 25% fat, 5% minerals, and <1% glycogen

Water - Bodily Functions

• Carries nutrients and waste products
• Maintains structure of large molecules
• Participates in metabolic reactions
• Solvent for minerals, vitamins, amino acids, glucose
• Lubricant and cushion around joints, inside the eyes, spinal cord, and amniotic fluid during pregnancy
• Regulates body temperature
• Maintains blood volume

Water Balance

• Water balance is the balance between water intake and excretion needed to maintain a constant water content in the body
• The average water intake consists of 2150 mL from fluids, 500 mL from food, and 300 mL produced from metabolism for a total of 2950 mL
• The average water output consists of 1950 mL from urine, 600 mL from skin perspiration, 300 mL from lung respiration, and 100 mL from feces for a total of 2950 mL

Body fluids and minerals

• Water flows freely across cell membranes and cannot be directly controlled by the body
• Water follows salt, therefore the body controls salt movement to control water movement

Fluids & Electrolytes

• Salt is a compound with a positive and negative ion; table salt is sodium chloride (NaCl)
• When salt dissolves in water, it separates into ions, which carry electrical current and are known as "electrolytes."
• A positively charged particle is called a cation
• A negatively charged particle is called an anion
• Cell membranes are selectively permeable and allow passage of some molecules
• Some electrolytes, like sodium and chloride, remain mostly outside of the cell
• Some electrolytes, like potassium, magnesium, and phosphate, remain mostly inside the cell
• Ion concentration controls how much water is inside versus outside of cells

Minerals Overview

• Minerals are individual chemical elements that cannot be broken down further
• Minerals are not energy-yielding
• Minerals are considered essential when a dietary inadequacy causes a physiological or structural abnormality, and including the mineral in the diet reinstates health
• Minerals are categorized by the amount needed in the diet each day
• Major minerals should be consumed at 100 mg or more per day
• Trace minerals should be consumed at less than 100 mg per day
• Ultratrace minerals are found in trace amounts in the diet, but are not essential to human health

Amounts of Minerals in the Human Body

• The body consists of relatively large amounts of Calcium, Phosphorus, Potassium, Sulfur, Sodium, Chloride and Magnesium
• The body also consists of trace amounts of Iron, Manganese, Copper and Iodine

Absorption and Storage of Minerals in the Body

• Bioavailability of minerals is affected by factors such as age, gender, genetic variables, nutritional status, diet, prescription drugs, and fiber content of the diet
• Zinc deficiencies in Middle Eastern populations are partly attributed to unleavened breads, like matzo, resulting in low bioavailability of dietary zinc

Minerals: Absorption

• Majority of minerals are absorbed in the small intestine
• Fiber, phytic acid, and oxalic acid decrease some mineral absorption
• Higher fiber diets decrease absorption of iron and zinc
• Vitamin C intake increases iron absorption
• Vitamin D intake increases calcium absorption
• Excess of one mineral can decrease absorption of another; higher zinc intake lowers copper absorption

Minerals: Storage

• Minerals are stored in various tissues
• Calcium, phosphorus, magnesium, and fluoride are stored in bone
• Iron, copper, zinc, and some trace minerals are stored in the liver
• Some minerals remain in the bloodstream
• Others are stored in muscle tissue, organs, and glands

Mineral Toxicities

• Supplements pose the biggest risk for mineral toxicity
• A general recommendation is to avoid intakes above 100% of Daily Values on supplement labels
• Harmful interactions with other nutrients can occur

Major Minerals

• Calcium
• Phosphorus
• Magnesium
• Sodium
• Potassium
• Chloride
• Sulfur

Calcium

• Functions in bone and teeth as the main structural component and reservoir of calcium supply for the blood
• Functions in blood/fluids for disease prevention by protecting against hypertension, high blood cholesterol, diabetes, and colon cancer, blood clotting, muscle contraction and nerve function
• 99% of calcium found in the body is in bones; 1% is in fluids and cells
• The amount of calcium in the blood is regulated by a complex hormone system

Calcium - Absorption

• The body absorbs more calcium when needed
• Pregnant women absorb 50% of the calcium they ingest
• Children or teens absorb 50-60% of the calcium they ingest
• Adults absorb 25% of the calcium they ingest
• Calcium absorption is enhanced by stomach acid, vitamin D, growth stage, and deficiency
• Calcium absorption is inhibited by lack of stomach acid, vitamin D deficiency, high phosphorus intake, and anti-nutritional factors

Calcium - Prolonged Deficiency/Bone Loss

• Osteoporosis is when calcium storage in bones is not adequate, resulting in a reduction in bone mass and weak bones that are prone to fractures

Calcium - Sources

• Milk and milk products are good sources of calcium
• Adding powdered fat free milk to dishes can help increase calcium; 5 tbsp = 1 cup of milk
• Other sources of calcium include tofu, corn tortillas, nuts and seeds, broccoli, and sardines with bones
• Calcium-fortified soy milk, almond milk, and rice milk also contain calcium

Phosphorus

• The 2nd most abundant mineral in the body
• Functions in bones and teeth; 85% found combined with calcium for structure
• Buffer system
• Assists DNA/RNA structure
• Assists with energy metabolism
• Phospholipids critical to cell membrane structure
• Sources include foods rich in protein, milk, cheese, dark sodas, and liver

Magnesium

• Over 1/2 of magnesium found in bones
• The rest is in muscles, heart, liver, and soft tissues
• 1% of magnesium is found in the blood
• Functions in bone and teeth health, energy metabolism, assists more than 300 enzymes, muscle contraction, heartbeat, and blood pressure

Magnesium - Deficiency and Toxicity

• Average U.S. intakes are low, but overt symptoms are rare
• Low magnesium intake increases risk for hypertension, CVD, Type 2 Diabetes, low bone mineral density, and possibly migraine
• Toxicity can result from nonfood sources like supplements or magnesium salt laxatives
• Toxicity symptoms include diarrhea, dehydration (usually self-limiting), disrupted pH balance, and a toxic effect on the liver

Magnesium - Sources

• Hard water, which contains high magnesium and calcium contents, is a source of magnesium
• People who live in areas with hard water tend to have low rates of heart disease
• Legumes, seeds, nuts, green leafy veggies, and dairy also contain magnesium

Sodium

• Sodium Chloride is also known as Table Salt
• Functions for appealing taste to enhance and suppress bitter flavors
• Principal cation of extracellular fluid
• Primary regulator of blood volume & fluid balance
• Aids in acid-base balance
• Aids in nerve impulse transmission
• Aids in muscle contraction

Sodium - CDRR

• Chronic Disease Risk Reduction(CDRR) is a DRI category
• CDRR intake level is under 2,300 mg
• There is no UL for sodium due to limited evidence of toxicity

Sodium - Chronic Overconsumption

• High sodium and low potassium in the diet are both associated with higher blood pressure
• This can lead to increased risk of developing cardiovascular disease and stroke
• Diets low in sodium and high in potassium can lower blood pressure, such as the DASH Diet (Dietary Approaches to Stop Hypertension)

Sodium - Acute Deficiencies

• Acute deficiency results from vomiting, diarrhea, heavy sweating
• Symptoms include: cramps, nausea/vomiting, dizziness, coma

Sodium - Recommended Intake

• AI adults should have 1,500 mg intake
• CDRR should have 2,300 mg intake
• Should be less than 2,300 mg for most adults and even normotensive people
• Most adults exceed CDRR and develop hypertension at some point

Sodium - Sources

• Processed or prepared foods that act as a preservative account for 75% of sodium sources
• 15% of sodium intake comes from salt added in cooking and at the table
• 10% of sodium intake is naturally found in foods

Potassium

• Functions as an intracellular cation
• Involved in fluid and electrolyte balance, cell integrity, nerve impulse transmission and muscle contraction
• Low potassium is associated with hypertension
• High potassium and low sodium diet may prevent and correct hypertension

Potassium - Recommended Intake & Deficiency

• AI for males is 3,000 mg
• AI for females is 2,300 mg
• Commonly underconsumed
• Almost any diet will prevent severe deficiency
• Medical conditions can cause severe depletion like severe diarrhea, vomiting, and purging eating disorders
• Chronic, sub-optimal intake causes increased blood pressure, salt sensitivity, kidney stones, and bone turnover

Potassium - Sources

• Abundant in all living cells, both animal and plant
• Cells remain intact unless foods are processed, making FRESH foods the best source of potassium
• At least 5 servings of fruits and vegetables per day is recommended to meet potassium needs

Chloride

• Functions as a major extracellular anion
• Works with sodium to maintain fluid and electrolyte balance
• Functions as part of HCl (hydrochloric acid) in the stomach to maintain strong acidity of gastric juices
• Abundant in many foods as part of sodium chloride or other salts containing sodium and is not generally a nutritional concern

Sulfur

• Abundant in water and foods
• Made from some amino acids found in dietary protein
• Skin, hair, and nails have high sulfur content
• Easily met with normal protein intakes; therefore there is no intake recommendation

Trace Minerals

• Iodine
• Iron
• Zinc
• Selenium
• Fluoride
• Others
• Contaminant Minerals

Iron

• The component of hemoglobin and myoglobin which transports oxygen in blood and muscles
• Cofactor for enzymes
• Prooxidant; very toxic at high dose and causes oxidative damage if too much

Types of Iron

• Heme iron is derived from the hemoglobin and myoglobin in meat
• The absorption rate of heme iron is 18-25%
• Non-heme iron is derived mainly from cereals, legumes, fruit and vegetables
• The absorption rate of non-heme iron is less than 5%
• Absorption is enhanced when eaten with Vitamin C

Iron Deficiency Anemia

• Major micronutrient deficiency that consists of 2.4 million cases in the US and 1.6 billion worldwide
• Primarily affects infants, children, and women during reproductive years
• Results in microcytic, hypochromic blood cells

Iron - Sources

• Beef/Red Meat
• Leafy greens(spinach, chard)
• Some beans, legumes
• Nuts and seeds
• Liver
• Whole grains, or enriched or fortified grains and cereals, cooked in a cast iron pan

Iodine

• Occurs in the body as iodide(salt form)
• Iodide forms part of thyroid hormones such as Triiodothyronine(T3) and Thyroxine(T4) which regulates body temperature, metabolic rate, and growth
• Deficiency causes both Goiter(adults) and Cretinism(infants)
• Can be found in both Seaweed and Iodized Salt

Zinc

• Functions as cofactor for ~100 enzymes
• Component of DNA-binding proteins
• Deficiency causes growth inhibition and diarrhea
• Interacts with iron

Fluoride

• Key component of teeth
• Present in fluorapatite versus Ca5(PO4)3(OH)
• Stabilizes bone and prevents teeth decay
• Found in fluoridated water and toothpaste
• Elevated levels cause toxicity/fluorosis

Selenium

• Selenium-containing proteins
• Antioxidant selenoproteins
• Needed for thyroid hormone synthesis
• Plays a role in preventing heart disease and cancer

Other Trace Minerals

• Chromium
• Copper
• Molybdenum
• Manganese
• Cobalt(Part of Vitamin B12)
• Nickel

Summary

• Deficiencies and excesses of the major minerals more dangerous than vitamin deficiencies because of their role as electrolytes
• Healthy body is good at homeostasis
• Chronic deficiencies and excesses of the major minerals lead to increased chronic disease risk
• Major vs. minor minerals refers to the amounts needed, not their importance