Lipids and Fatty Acids
The biochemistry of fat, and better dietary options.
Fatty acids are made of hydrocarbon chains ending in a carboxylic acid. In biological environments, they are predominantly present in their conjugate base (carboxylate) form.
Fats are of two kinds, saturated and unsaturated. Saturated fats contain only single bonded carbons (alkane bonds), while unsaturated fats contain some double bonds.
Saturated Fatty Acids and Common Sources
| Carbon Chain | Common Name | Primary Sources | Additional Sources |
|---|---|---|---|
| 2C | Acetic acid | Vinegar | Fermented foods |
| 3C | Propionic acid | Butter | Swiss cheese, sourdough |
| 4C | Butyric acid | Butter | Goat milk, parmesan cheese |
| 5C | Valeric acid | Butter | Valerian root |
| 6C | Caproic acid | Butter | Goat fats, ginkgo seeds |
| 12C | Lauric acid | Coconut oil | Palm kernel oil, breast milk |
| 14C | Myristic acid | Coconut oil | Nutmeg, palm oil, butterfat |
| 16C | Palmitic acid | Animal fat | Palm oil, meat, cocoa butter |
| 18C | Stearic acid | Animal fat | Cocoa butter, shea butter, lard |
Unsaturated fats are of two kinds, monounsaturated, which contain a single double bond, and polyunsaturated, which contain more than one double bond.
Unsaturated Fatty Acids and Common Sources
| Type | Common Name | Carbons | Double Bonds | Primary Sources |
|---|---|---|---|---|
| MUFA | Palmitoleic Acid | 16 | 1 | Mustard oil, macadamia nuts |
| MUFA | Oleic Acid | 18 | 1 | Rapeseed oil, olive oil, avocado |
| MUFA | Elaidic Acid | 18 | 1 | Rapeseed oil |
| PUFA | Linoleic Acid | 18 | 2 | Safflower oil, sunflower oil, corn oil |
| PUFA | Linolenic Acid | 18 | 3 | $\alpha$-flaxseed, $\gamma$-evening primrose |
| PUFA | Arachidonic Acid | 20 | 4 | Body fat, poultry, eggs |
| PUFA | Timnodonic Acid (EPA) | 20 | 5 | Fungal, algal, salmon/sardines |
| PUFA | Cervonic Acid (DHA) | 22 | 6 | Fungal, algal, breast milk, fish oil |
Another way to classify unsaturated fatty acids is by the position of the double bond. Along this vein, we have Omega-3, Omega-6, and Omega-9 fatty acids. The numbers represent the position of the final double bond from the end or the tail of the chain.
The human body cannot produce Omega-3 fatty acids, and these have to be supplemented in our diets. The three most common are:
- Timnodonic Acid (Eicosapentaenoic Acid or EPA)
- Cervonic Acid (Docosahexaenoic Acid or DHA)
- $\alpha$-Linoleic Acid (ALA)
Omega-6 fatty acids are also essential, but western diets have an excess of these:
- $\gamma$-Linoleic Acid (GLA)
- Linoleic Acid (LA)
- Arachidonic Acid (AA)
Omega-9 fatty acids are monounsaturated, and are not essential, because our body can produce them.
Health Benefits
| Feature | Omega-3 (Polyunsaturated) | Omega-6 (Polyunsaturated) | Omega-9 (Monounsaturated) |
|---|---|---|---|
| Status | Essential (Must eat it) | Essential (Must eat it) | Non-essential (Body can make it) |
| Primary Benefits | Heart health, brain function, reducing inflammation, eye health. | Provides energy, supports skin health, bone health, and metabolism. | Supports heart health, improves insulin sensitivity, reduces inflammation. |
| Common Sources | Fatty fish (salmon, sardines), walnuts, chia seeds, flaxseeds. | Soybean oil, corn oil, sunflower seeds, walnuts, poultry, eggs. | Olive oil, avocado oil, almonds, cashews, peanuts. |
| Role in Body | Integral part of cell membranes; precursor to anti-inflammatory hormones. | Necessary for growth and repair, but can be pro-inflammatory if excessive. | Not a “requirement” but a healthy replacement for saturated fats. |