Recording 21-14

Calcium

• Dietary Sources:

  • Dairy Products: Milk, cheese, and yogurt are excellent primary sources of calcium, providing high bioavailability. Ice cream can also contain calcium but typically has added sugars and fats, which reduce its overall health benefits.

  • Fish: Sardines with edible bones and other seafood are rich in calcium and also provide beneficial omega-3 fatty acids.

  • Vegetables: Green leafy vegetables such as broccoli and bok choy are not only rich in calcium but also high in vitamins and minerals, which aid in overall health.

  • Legumes and Dried Fruits: Beans, lentils, almonds, and dried fruits like figs and apricots contain varying amounts of calcium, making them important for vegetarians and those seeking non-dairy sources.

  • Fortified Foods: Calcium-fortified foods, including certain juices and cereals, are increasingly important in the diet for those who may not consume enough calcium through traditional sources.

  Dietary Sources:

  • Seafood: Fish and shellfish are rich sources of iodine due to their marine environment.

  • Eggs and Dairy Products: Foods like eggs, milk, and cheese are good sources, particularly cheddar cheese and skim milk, often containing significant amounts of added iodine.

  • Iodized Salt: Table salt with added iodine is a common source in many diets, crucial for individuals not consuming sufficient natural sources.

• Function:

  • Iodine is a vital component of thyroid hormones (T3 and T4), which play key roles in regulating energy metabolism, growth, and protein synthesis. These hormones are particularly crucial for fetal brain and skeletal development, emphasizing iodine's importance during pregnancy.

  • T3 is the more active form, with a more significant metabolic impact compared to T4.

  States of Iron:

  • Ferrous Iron (Fe2+): This form is more readily absorbed by the intestine, making it crucial for efficient iron supplementation.

  • Ferric Iron (Fe3+): Less efficiently absorbed; presence in the diet necessitates specific conditions for optimal absorption.

• Dietary Sources:

  • Heme Iron: Found in animal-based foods like red meat, liver, clams, and oysters, which are absorbed more effectively by the body.

  • Non-Heme Iron: Present in plant-based foods such as beans, nuts, seeds, and fortified cereals, but is significantly less absorbed compared to heme iron.

  • Absorption Efficiency: Heme iron absorption ranges from 25-35%, while non-heme iron is only 2-20%, making dietary choices critical for those at risk of deficiency.

• Function:

  • Critical for hemoglobin production, iron enables red blood cells to carry oxygen throughout the body efficiently. It also acts as an enzyme co-factor, necessary for various metabolic processes including energy production.

• Factors Affecting Absorption:

  • Enhancers: Vitamin C and gastric acidity promote iron absorption, especially when consumed with plant sources of iron.

  • Inhibitors: Compounds like phytates in grains, oxalates in leafy greens, tannins in tea, and excess calcium can bind to iron in the gut, significantly hindering absorption.

• Storage and Transport:

  • Iron is predominantly stored in the protein ferritin, and it's transported by transferrin in the bloodstream to various tissues, ensuring availability for critical physiological functions.

• Special Considerations:

  • Pregnant women and children often require increased iron intake to support growth and development. Vegetarians may also need to be mindful of their iron sources due to lower absorption rates of non-heme iron.

Alcohol

• Type: Ethyl alcohol or ethanol, commonly found in fermented drinks such as beer and wine, as well as distilled beverages like rum and vodka, which can vary widely in their alcohol content.

• Energy Content: Alcohol contains 7 calories per gram, which can contribute significantly to the total energy intake of those who consume alcohol regularly. This underscores the importance of moderation, particularly in individuals with weight management goals.

• Metabolism:

  • Primarily occurs in the liver and involves two systems:

  • Alcohol Dehydrogenase: Enzymes that convert ethanol to acetaldehyde, a toxic byproduct that can impair cellular function.

  • Microsomal Ethanol Oxidizing System (MEOS): A secondary pathway activated during high alcohol intake, leading to increased tolerance but also to a higher risk of alcohol-related damage.

• Absorption: Ethanol absorbs rapidly, effectively crossing the gastrointestinal tract and blood-brain barrier, resulting in quick effects on the central nervous system in moderate to high consumption levels.

• Toxicological Effects:

  • Acetaldehyde, produced during ethanol metabolism, is toxic and can bind to proteins and nucleotides, forming adducts that impair cellular function, potentially leading to tissue damage and organ failures. Chronic alcohol consumption can result in severe conditions such as liver cirrhosis, neurological damage, and increased risk for certain cancers, highlighting the importance of responsible use.