Ketogenic_diet
The Ketogenic Diet: A Comprehensive Review of Its Benefits, Potential Adverse Effects, and Nutritional Sources
1. Introduction
The ketogenic diet (KD) is a high‑fat, moderate‑protein, low‑carbohydrate eating pattern that induces a metabolic state known as ketosis. In ketosis, the liver converts fatty acids into ketone bodies—β‑hydroxybutyrate, acetoacetate, and acetone—which serve as alternative energy substrates for tissues such as brain, heart, and skeletal muscle. Historically developed in the 1920s to treat refractory epilepsy, KD has since been explored for a wide range of conditions including metabolic disorders, neurodegenerative diseases, obesity, and certain cancers.
Cholesterol
Cholesterol: Functions, Clinical Manifestations, and Dietary Sources
1. Introduction
Cholesterol is a sterol lipid that plays pivotal roles in human physiology. Although often vilified for its association with cardiovascular disease (CVD), cholesterol is indispensable for cellular integrity, hormone synthesis, bile acid formation, and vitamin D production. A nuanced understanding of its benefits, pathological consequences, and dietary origins is essential for clinicians, researchers, and public‑health practitioners alike.
2. Physiological Roles of Cholesterol
| Function | Mechanism | Clinical Relevance |
|---|---|---|
| Membrane structure | Contributes to membrane fluidity and the formation of lipid rafts that organize signaling proteins. | Altered membrane cholesterol can affect receptor function and ion transport, influencing neuronal excitability and cardiac conduction. |
| Precursor for steroid hormones | 7‑dehydrocholesterol → pregnenolone → progesterone, cortisol, aldosterone, estrogens, andandrogens. | Hormonal deficiencies (e.g., adrenal insufficiency) may stem from impaired cholesterol availability. |
| Bile acid synthesis | Hepatic conversion to cholic and chenodeoxycholic acids for lipid emulsification in the gut. | Cholestasis or bile duct obstruction can lead to cholesteryl ester accumulation and gallstone formation. |
| Vitamin D production | 7‑dehydrocholesterol in skin absorbs UVB → previtamin D3 → vitamin D3. | Vitamin D deficiency is linked to bone disorders, immune dysfunction, and increased CVD risk. |
3. Cholesterol Homeostasis
The body maintains cholesterol levels through a balance of intake, synthesis, absorption, transport, and excretion.
Zinc
The Multifaceted Role of Zinc in Human Health
A comprehensive review for a science‑and‑technology audience
1. Introduction
Zinc (Zn) is an essential trace element that participates in more than 300 enzymatic reactions and plays pivotal roles in cellular proliferation, signal transduction, gene expression, and immune competence. Although required only in minute amounts—approximately 8 mg/day for adult women and 11 mg/day for adult men—the importance of maintaining adequate zinc status cannot be overstated. This review synthesises current evidence on the physiological functions of zinc, its health benefits, clinical manifestations of deficiency, and dietary strategies to optimise intake.