Nutrition material 7.5

Vitamins and Minerals: Micronutrients with Macro Powers

• After studying this content, you should be able to:

  • Describe some incidents that led to the discovery of micronutrients.

  • Distinguish between fat-soluble and water-soluble vitamins.

  • Describe the differences between major, trace, and ultra-trace minerals.

  • Explain why the amount of a micronutrient consumed may differ from absorption and usage in the body.

  • Discuss the role of micronutrient supplements in health.

Incidents Leading to the Discovery of Micronutrients

• Scurvy urban legend among college students highlights the importance of micronutrients.

• Many college students adopt diets deficient in micronutrients (e.g., vegan diets lacking iron).

• The role of vitamins and minerals is crucial for health; deficiencies can be harmful.

• Historical observations:

  • C. Eijkman's discovery in the 1890s: Chickens fed polished rice developed paralysis, which was reversed with whole-grain rice containing thiamin.

  • Japanese children in fishing villages had lower rates of blindness due to consumption of fish high in vitamin A.

• F.G. Hopkins coined the term "accessory factors" for substances now known as vitamins and minerals in 1906.

Classification of Vitamins

Fat-Soluble Vitamins

• Vitamins A, D, E, and K are fat-soluble.

• Sources: Found in fatty foods (e.g., oils, avocados, dairy products).

• Stored in adipose tissue and liver; can lead to toxicity.

• Deficiency risks include malabsorption disorders (e.g., celiac disease).

Water-Soluble Vitamins

• Include vitamin C and B-complex vitamins (thiamin, riboflavin, niacin, B6, B12, folate, pantothenic acid, biotin).

• Easily absorbed into the bloodstream, excreted in urine.

• Toxicity is rare, but can occur with supplements.

Differences between Major, Trace, and Ultra-Trace Minerals

Major Minerals

• Required in amounts of at least 100 mg/day; total body content > 5 g.

• Examples: sodium, potassium, calcium.

Trace Minerals

• Required in amounts < 100 mg/day; total body content < 5 g.

• Examples with established RDAs: iron, zinc, fluoride.

Ultra-Trace Minerals

• Required < 1 mg/day; e.g., chromium, copper, iodine.

Absorption versus Intake of Micronutrients

• Factors affecting absorption:

  • The chemical form of nutrients affects how much the body absorbs (e.g., heme vs. non-heme iron).

  • Competition and synergistic effects of different nutrients.

  • For example, calcium absorption can be enhanced by lactose content, while some plant sources hinder absorption.

Role of Micronutrient Supplements

• Supplements easier to reach toxic levels than foods.

• Some high-dose supplements may be harmful; e.g., high vitamin E and beta-carotene may increase health risks.

• Minerals are generally better absorbed from food than from supplements, with notable exceptions.

• Balanced diets are preferable as they provide additional nutrients and benefits beyond just vitamins and minerals.

Food Preparation and Nutrient Preservation

Tips for Preserving Vitamins

• Minimize water use to retain water-soluble vitamins during cooking.

• Store vitamins in opaque containers to protect them from light.

• Avoid high temperatures; stick to steaming or microwaving vegetables for nutrient retention.

Future of Micronutrient Research

• Ongoing exploration of substances that may qualify as essential micronutrients.

• Possible development of personalized micronutrient prescriptions based on DNA and individual needs.

Case Study: Nutritional Decisions of College Students

• Example of college student Michaela who emphasizes cereal for micronutrients; necessity of balanced meals throughout the day is important for overall nutrition.