Adaptation to Biological Stressors: Malnutrition

Adaptation to Biological Stressors, Part 1: (Mal)Nutrition

• The presentation covers malnutrition and its types, as well as the global issue of overnutrition.
• Malnutrition is divided into three categories: too little, too much, and poorly balanced.

Types of Malnutrition

• Too little: Protein-calorie malnutrition (PCM). Includes periods of starvation, total lack of food, and insufficient food quantity/quality.

• Too much: Overabundance is also a type of malnutrition.

• Poorly balanced: Chronic micronutrient malnutrition, meaning an unbalanced diet.

Global Health Crisis

• Obesity is now killing more people than malnutrition worldwide. A landmark study reported more than three million annual deaths from obesity.

Prevalence of Undernourishment

• A world map shows the global distribution of malnutrition, highlighting regions with high rates. Different colors represent percentage levels of undernourishment in a given area.

Prevalence of Obesity

• Another world map displays the prevalence of obesity, using color-coded regions to present data on the percentage of the population considered obese (BMI over 30).

Nutrients vs. Food

• The presentation differentiates between nutrients and food. Images illustrate the diversity of foods and their potential nutritional content.

Nutrients

• Nutrients are categorized into energy and materials, macronutrients, and micronutrients.
  • Macronutrients are further broken down into carbohydrates, proteins, and lipids (fats).
  • Micronutrients include vitamins and minerals. Specific examples of food sources often associated with the given category were highlighted visually.

Protein

• Proteins are composed of amino acids linked together. These amino acids are either essential, meaning the body cannot produce them, or nonessential, meaning the body can produce them.

• Proteins can be broken down to create other amino acids.

• Some amino acids are essential and must be consumed from food. A deficiency in any essential amino acid can cause a protein deficiency in the body. An example is a diet solely relying on a single plant source.

Protein Quality of Foods

• The presentation highlighted the Mesoamerican diet, using beans and maize as examples, for its balanced protein sources.

• The study notes emphasize several plants (like beans and maize) provide sufficient essential amino acids, minimizing the risk of deficiencies.

Protein Deficiency

• A map shows regions with high rates of stunting (a type of growth retardation caused by inadequate nutrition) related to protein deficiencies.

Energy Reserves

• Body uses glycogen, fat, and protein for energy. Glycogen is used first, followed by fat. Protein is the last resort.

Biology of Deficiency

• Protein-calorie malnutrition (PCM) leads to depleted glycogen and fat reserves, then to protein breakdown to produce energy.

• This leads to muscle wasting, immune system impairment, and an increased risk of growth disruptions in children, resulting in conditions like Kwashiorkor and Marasmus. Kwashiorkor is characterized by protein deficiencies. Marasmus is a severe form of malnutrition.

Growth Disruptions

• Children have similar growth patterns, but protein is crucial for growth. Problems such as stunting (reduced linear growth) and wasting (low weight-for-height) indicate growth disruptions. Harris lines in bones denote slowed growth due to physiological stress.

Micronutrient Deficiencies

• Micronutrients like vitamins and minerals are crucial for many bodily functions; deficiencies frequently arise from a poor-quality diet or reliance on a limited food source.

Vitamin A (Retinol)

• Derived from beta-carotene. Stored in the liver. A deficiency can lead to “night blindness,” dry skin, brittle nails, and dry hair. A global map illustrated areas with differing levels of vitamin A.

Vitamin B1 (Thiamine)

• Critical for carb. and protein metabolism and neurotransmitter production. A deficiency—related to consumption of milled rice vs. whole grain rice—results in beriberi, affecting the heart & circulatory & nervous and muscle tissue.

Vitamin C (Ascorbic Acid)

• Critical for collagen production (necessary for wound healing and overall tissue repair). This vitamin deficiency leads to scurvy (symptoms include bleeding gums, skin issues, etc). The presentation indicated that scurvy historically affected those who traveled long distances without adequate access to fresh food.

Vitamin D (calcitriol)

• Essential for calcium absorption. Deficiencies can result in conditions like Rickets(in children) and Osteomalacia (in adults), problems involving bone development and mineralization. The slides present a visual example of how this vitamin functions within the body.

Micro-nutrient deficiencies summary

• Micronutrient deficiencies can result from a limited range of food choices, or a poor diet. The slides demonstrate the prevalence of certain vitamin and mineral deficiencies in certain areas of the world.

Electrolytes

• Important minerals with an electric charge present in tissues and body fluids. The four major electrolytes are magnesium, calcium, sodium, and potassium.

Iron Deficiency

• Anemia, fatigue, neurological problems, immune dysfunction, and hair loss are symptoms of this prevalent nutrient deficiency. The slideshow emphasizes the prevalence of this issue globally.

Iodine

• Iodine is essential for thyroid hormone production, metabolism and development. Deficiency can cause goiters and hypothyroidism. The slideshow includes pictures of foods that are rich in iodine, and a visual showing the prevalence and distribution in the world.

Lactose Tolerance

• Lactase activity decreases with age. Lactose intolerance/malabsorption results when lactase is not produced. The presentation introduces the concept that a population's tolerance to milk is tied to their history and culture. The slideshow shows regions where the prevalence of lactose tolerance is higher, and lower.

Convergent Evolution of Lactase Persistence

• Lactase persistence evolved independently in different regions. This suggests a common selective pressure—most likely associated with cultural practices tied to milk consumption—over the past 5,000-10,000 years.

Co-evolution of Genes and Culture

• Cultural practices like animal domestication influence human genetic adaptations. The presentation focuses on the interconnectedness of culture and genetics, linked specifically to adult milk consumption. Adaptation to milk consumption appears to have strong cultural implications.

Tinbergen's Four Questions

• How can we use the four questions to understand the variation in lactose persistence?

Critical Analysis of Biological Claims

• Why would biologists critique claims about race and genetics?

This quiz covers the essential aspects of malnutrition, including its types and the global health crisis of overnutrition. Explore the definitions, prevalence, and significant statistics related to both undernourishment and obesity. Understand how different forms of malnutrition impact global health.