Overview
This lecture explains the use of metric and US customary units for mass, volume, and length in nutrition, and provides important conversion factors relevant to human nutrition studies.
Measurement Systems in Nutrition
- Nutrition commonly uses both the metric system and the US customary system due to lack of complete metric adoption in the US.
- The metric system includes prefixes for easier measurement of small or large quantities.
Common Metric Prefixes
- Micro- (μ) means one millionth (1/1,000,000).
- Milli- (m) means one thousandth (1/1,000).
- Centi- (c) means one hundredth (1/100).
- Deci- (d) means one tenth (1/10).
- Kilo- (k) means one thousand times (1,000).
Mass Units and Conversions
- Metric mass units: microgram (μg), milligram (mg), gram (g), kilogram (kg).
- US customary mass units: ounce (oz), pound (lb).
- Key conversions: 1 oz = 28.35 g, 1 lb = 454 g, 2.2 lbs = 1 kg.
Volume Units and Conversions
- Metric volume units: milliliter (mL), deciliter (dL), liter (L).
- US customary volume units: teaspoon (tsp), tablespoon (tbsp), fluid ounce (fl oz), cup (c), pint (pt), quart (qt), gallon (gal).
- Key conversions: 1 tsp = 5 mL, 1 tbsp = 15 mL, 1 fl oz = 30 mL, 1 c = 237 mL, 1 qt = 0.95 L.
Length Units and Conversions
- Metric length units: millimeter (mm), centimeter (cm), meter (m), kilometer (km).
- US customary length units: inch (in), foot (ft), yard (yd), mile (mi).
- Key conversions: 1 in = 25.4 mm, 1 ft = 30.5 cm, 1 yd = 0.9 m, 1 mi = 1.6 km.
Key Terms & Definitions
- Metric System — an international decimalized system of measurement based on units of ten.
- US Customary System — a system of measurement used mainly in the United States, including units like inches and pounds.
- Prefix — a word part added to a unit to indicate a multiple or fraction.
- Conversion Factor — a multiplier used to convert a quantity from one unit to another.
Action Items / Next Steps
- Practice converting between metric and US customary units using the provided conversion factors.
- Review interactive learning activities in the web-based textbook for further understanding.