5: Metabolism and Nutrition

Dental disease:

• Tooth wear

• Dental caries (cavities) – tooth decay

• Periodontal disease (gum and bone)

• Tooth loss

• Malocclusion (misalignment of teeth)

Tooth anatomy

• Nerve cells

• Mandible and maxilla – spongy bone

• Enamel – outermost surface

• Dentin – most of crown

• Pulp – vascularized (entrance to blood stream)

• Periodontal membrane – gums

Enamel erosion – citrus, alcohol, soft drinks, smoking

• Fluoride counteracts erosion

Cavities

• Demineralization of hard dental tissue

• Caused by Streptococcus mutans bacteria

• Waste products of bacteria are acidic

Buildup of calculus (plaque)

• Gingivitis – just affects gum

• Periodontitis – affects bone and gum

• Causes – bleeding gums, pockets in gums

• Increased prevalence with agriculture (high carbohydrate foods)

Malocclusion

• Increasing trends over time

• Food softening – jaws don’t remodel enough

• Genetics

• Jaw size decreased over time

Infectious disease evidence

Syphilis (non-sexually transmitted and sexually transmitted types)

Dental disease

• Tooth loss, periodontal disease

• Enamel hypoplasia – childhood stress, malnutrition

• Tooth wear (teeth as a tool, intentional modification)

• Dental caries more common in agricultural societies than hunter-gatherers and mixed economies

Decreasing rates in dental caries due to fluoride, dental hygiene

Dental caries risks:

• Soft drinks, alcohol, smoking

• Dental hygiene issues and lack of dental treatment

• Lead exposure

• Bottled water without fluoride

• Medications that affect pH of saliva

Fibrous diet – leads to flattened wear on teeth

Diet high in shellfish – leads to slanted/angled wear on teeth

3rd molar – last to erupt and least worn

Teeth on mandible wear faster than teeth on maxilla

Pancreas creates insulin which takes glucose out of blood

Type I – pancreas does not produce insulin (genetic)

Type 2 – pancreas cannot keep up with demand

• Too much glucose in blood

• Fatty tissue makes it harder for cells to respond to insulin

Glucose buildup

• Blindness

• Poor circulation

• Nerve damage

• Amputation

• Glucose crystals cause tears in blood vessels

Proposed that some populations had characteristics that predispose people to diabetes provided a survival advantage in times of famine

• Slower metabolism

• Increased fat storage

Mismatch between environment in which the human brain evolved and the environments humans live in today

Some have higher genetic risk than others

However, debated heavily

Genotype – genetic material (alleles that an organism has)

Phenotype – outward appearance of a trait (eye color, hair color, height, etc.)

• Individuals can have physical traits that look the same, but the underlying genes differ

Perhaps disease risk is more heavily determined by epigenetic factors

Epigenetics – study of reversible changes in DNA that do not involve genetic alterations in DNA sequence

• Environmental influences on phenotype

However, there is some evidence of genes in isolated islands that do support thrifty genotype hypothesis

• For example, genetic predisposition for slower metabolism and increased fat storage in Samoan islanders, BUT there is not a link with type 2 diabetes

• Very common in the isolated population and rare in other populations

Research is still ongoing

Thyroid disorders – some are autoimmune; can affect metabolism (converting food into energy to run cellular processes)

Diverticulitis – holes in colon; lack of fiber in diet

Crohn’s disease/IBD – Inflammatory bowel disease

• Immune system is not necessarily triggered by the body itself, but it results in chronic inflammatory responses

Celiac disease – autoimmune disorder where villi in small intestine are damaged from immune response

• Gluten sensitivity (sensitive GI tract) does not necessarily cause damage to small intestine, so it is distinguished from Celiac

Gallstones

• Hardened deposits of digestive fluids

• Low fiber, high fat diets

• Overactive gallbladder

Ulcers

• Used to be seen as stress-related

• Infection caused by bacterium Heliobacter pylori

Lactose intolerance

• Not necessarily a disorder, but results from genetic differences in populations

• Globally, more people are lactose intolerant than tolerant

• Lactase enzyme isn’t produced

Appendicitis – bacterial growth causes inflammation

• Rupture would release bacteria into abdomen, resulting in sepsis (shock)

Cirrhosis

• Chronic inflammation of the liver

• Damaged liver tissue is replaced by fibrous tissue and adipose

• Causes:

  • Alcohol

  • Hepatitis

Non-communicable diseases influenced by junk food and sedentary lifestyle

• Obesity, heart disease, diabetes, hypertension

• Especially affects vulnerable populations (genetic risks, comorbidities, environmental stressors related to socioeconomic status and discrimination, and intergenerational trauma?)

Past populations

• Lack of cardiovascular disease?

• Difficult to find skeletal evidence

• Shorter lifespans – there possibly wasn’t time for chronic effects to develop

Past populations

• Egyptian mummies with hardened arteries

• 4000 year old Chilean mummy with heart disease from parasite

• 300 year old Alaskan mummies with heart disease linked to bacterial infections

• In past populations, links to heart disease from infections

Humans compared to other animals

• Shortened, less complex digestive system means less energy spent on digestion and more on other organs (like the brain)

• Cooking food helps remove some of the steps needed in digestive process

• Gut microbes aid in digestion

Humans and increased dental issues

• Other animals consume higher amounts of fiber (and digestive system can handle it)

• Other animals tend to have less acidic, carb-rich, sugary diet

• Other animals have shorter lifespans

• Domesticated animals have more dental issues (carbs, sugar)