Overview
This lecture reviews water-soluble vitamins and introduces chapter 12 on major minerals, including their characteristics, categories, and factors affecting absorption.
Water-Soluble Vitamins Review
- Not all water-soluble vitamins are destroyed during cooking; some are stable.
- Biotin and pantothenic acid are unique vitamins, not forms of vitamin C.
- B vitamins do not directly provide energy but are essential for energy metabolism.
- The body cannot synthesize enough niacin from tryptophan; niacin is essential.
- Excess B6 can cause nerve damage.
- Older adults have reduced B12 absorption due to lower stomach acid and intrinsic factor.
- Folate reduces risk of specific birth defects.
- Pantothenic acid is abundant in foods and deficiency is rare.
- Raw egg whites inhibit biotin absorption due to the protein avidin.
- Vitamin C supplements do not prevent colds but may reduce severity in deficient individuals.
Introduction to Major Minerals
- Minerals are the fifth nutrient group studied after carbohydrates, lipids, proteins, and vitamins.
- There are over 90 minerals, but only 14 are essential for human health.
- Minerals must be obtained from the diet to prevent deficiency symptoms.
- Minerals are inorganic, contain no carbon, and provide zero calories.
- Major minerals are needed at amounts above 100 mg/day; trace minerals are needed below 100 mg/day.
- Example: Calcium is a major mineral (RDA > 1,000 mg/day); iron is a trace mineral (RDA 8–18 mg/day).
General Characteristics of Minerals
- Most minerals are insoluble in water (unlike vitamins).
- Minerals tend to be more stable than vitamins during heat, light, or oxygen exposure.
- Cooking and processing can increase mineral bioavailability in some cases.
Mineral Bioavailability
- Bioavailability refers to how well a nutrient is absorbed and used by the body.
- Factors that increase bioavailability: deficiency of the mineral, cooking, vitamin C (for iron), vitamin D (for calcium, phosphorus, magnesium), and higher stomach acidity.
- Factors that decrease bioavailability: food binders like oxalates (in spinach), phytates, and polyphenols (in tea and coffee).
- Excess supplementation of one mineral may interfere with the absorption of others.
Key Terms & Definitions
- Bioavailability — how much of a nutrient is absorbed and utilized by the body.
- Major minerals — minerals needed in amounts above 100 mg/day.
- Trace minerals — minerals needed in amounts below 100 mg/day.
- Oxalates, phytates, polyphenols — compounds in foods that reduce mineral absorption by binding to them.
- Intrinsic factor — a stomach protein needed for vitamin B12 absorption.
Action Items / Next Steps
- Review the roles and sources of the 14 essential minerals.
- Learn the specific functions, deficiencies, and toxicities of the major minerals in the upcoming chapters.