Fatty acids
🥩 Fatty acids are long-chain carboxylic acids that act as the body’s major energy source, building blocks of membranes 🧱, and precursors for signaling molecules 📡. Their structure and metabolism influence both health and disease.
🔑 Key Concepts
- Types of Fatty Acids:
- 🧈 Saturated (no double bonds) – solid at room temp. Found in butter, lard, animal fats. ↑ LDL, ↑ CV risk.
- 🥑 Unsaturated (≥1 double bond):
- Monounsaturated (MUFA): e.g., Oleic acid in olive oil → cardioprotective ❤️.
- Polyunsaturated (PUFA): e.g., Linoleic (Ω-6), α-linolenic (Ω-3). Found in nuts, fish oil 🐟.
- 🍟 Trans fats (hydrogenated oils) – unnatural configuration, linked to atherosclerosis & metabolic disease ❌.
- Essential Fatty Acids (must come from diet):
- Omega-3 (ALA, EPA, DHA) → 🧠 brain, retina, anti-inflammatory.
- Omega-6 (linoleic acid) → pro-inflammatory mediators ⚡.
⚙️ Functions of Fatty Acids
- 🔥 Energy: β-oxidation in mitochondria → acetyl-CoA → Krebs + ETC → ATP.
- 🧱 Structural: Incorporated into phospholipids → control membrane fluidity & signaling platforms.
- 📡 Signaling: Precursors for eicosanoids (prostaglandins, leukotrienes, thromboxanes).
- 🛡️ Protection: Stored in adipose → insulation + shock absorption.
🔄 Metabolism
- β-Oxidation (mitochondria) – FA → acetyl-CoA + NADH + FADH₂ → ATP.
- Ketogenesis (liver, fasting/starvation) – acetyl-CoA → ketone bodies (acetoacetate, β-hydroxybutyrate, acetone). Fuel for 🧠 brain & 🫀 heart.
- Fatty Acid Synthesis (cytoplasm) – Acetyl-CoA → Malonyl-CoA → Palmitate (16C). Uses NADPH (from PPP & malic enzyme).
🩺 Clinical Relevance
- ❤️ Cardiovascular: High saturated/trans fats → ↑ LDL, atheroma. Omega-3 ↓ triglycerides, stabilises plaques.
- ⚖️ Obesity: Excess fat storage → metabolic syndrome, insulin resistance.
- 🩸 Diabetes: Altered lipid metabolism → ↑ lipotoxicity, impaired insulin signalling.
- 🔥 Inflammation: Ω-6 eicosanoids = pro-inflammatory; Ω-3 = anti-inflammatory balance.
- 🧠 Neurology: DHA crucial for synapse function, retina development. Deficiency → cognitive decline.
📌 Quick Summary
🧈 Saturated = Solid, ↑ LDL.
🥑 Unsaturated = Healthy, ↑ membrane fluidity.
🐟 Omega-3 = anti-inflammatory, neuroprotective.
🔥 β-oxidation = ATP; 🧠 fasting = ketones.
❤️ Clinical: Trans fats → atheroma, Omega-3 → CV protection.
