From the previous blog post, you're familiar with saturated and unsaturated fatty acids. Now we’ll look at how we obtain and use fats (synonyms: fatty acids, triglycerides. lipids), how much we need/don’t need, and why.
Triglycerides (TG): You’ve seen this term on every blood panel your doctor has ever ordered, but what does it mean and why should we care? Fasting blood-borne TG levels higher than 150 mg/dL correlate with increased risk for heart disease, fatty liver disorder, early onset type II diabetes, kidney disorders and pancreatitis (Article). Usually the effects are asymptomatic until something alarming happens and we find a doctor. TG blood screens are recommended yearly to identify high levels before they cause problems.
Triglyceride with 1) Palmitic acid, 2) Oleic acid and 3) Linoleic acids hitched on. Notice different saturation.
We get fats from two different sources: 1) our diet, 2) our liver synthesizes them from other molecules in our bodies including glucose. Yes, when you eat excess sugar, your liver uses it to make fat. (Bummer). In plants and animals, fatty acids tend to travel in threes hitched to a glycerol molecule. The glycerol carrier molecule isn’t choosy about who hooks into those three sites, so one glycerol ‘car’ can have three different fatty acid ‘riders’ varying in length or saturation-style (see image). If only one FA is hooked up, it’s a mono-glyceride, if two, a di-glyceride, and three, a tri-glyceride. This latter form is how fats mostly occur in our bodies. TGs are very large energy-dense molecules, and a lean adult has enough TG stored in them (about 15 kg or 33 pounds) to survive for more than 2 months.
For us to access the energy in dietary fats, our digestive process performs a multi-step process to break TGs down into molecules small enough to cross the intestinal lining.
Feasting: When we eat, 1) we break large fat particles into smaller ones by chewing and stomach churn. 2) most TG disassembly happens in the small intestine where enzymes rip two fatty acids off the glycerol triple-carrier to liberate free fatty acids and mono-glycerides. 3) These smaller molecules are emulsified further by the addition of bile, and are finally able to cross the microvilli membrane into the intestinal cells. 4) Once inside the intestinal cells, the TGs are reassembled into their prior triplet form, and packaged with other goodies like cholesterol and fat-soluble vitamins (A,D,E), into shipping containers called chylomicrons. 5) The chylomicron containers are shipped into the intestinal lymph system and thence into the bloodstream to deliver TGs, vitamins and cholesterol to the tissues. If cells don’t need the energy, excess TGs are instead delivered to our storage units - adipose tissue for later use. Chylomicrons decrease in size as they deliver their load to the periphery and then the empty containers return for recycling in the liver.
Fasting: When we are not eating, 1) “Need Fuel!” signals are released by cells when their energy supplies run low. These signals hit two targets. 2) Our storage units (adipose tissue) react by breaking stored TGs into free fatty acids (mono-glycerides). The mono-glycerides diffuse into the blood, and head off to the cells that need energy, for example, your leg muscle cells if you are going for a walk. 3) The liver responds by constructing new TG’s from the free fatty acids floating in the blood stream plus glucose (we use sugar to make fat!! Bummer again.) 4) The liver packages the TG and some cholesterol and protein into VLDL (very low density lipoprotein) shipping containers and sends them out in the blood. The name very low density means they contain more TG than the accompanying heavier protein and cholesterol. As the traveling VLDL shipping containers drop their TG cargo into energy-requiring cells, they become LDLs, (low density lipoproteins - relatively more protein and cholesterol-laden, see previous post on cholesterol), then IDLs (intermediate density lipoproteins), and then finally HDLs (high density lipoproteins) mostly empty protein vehicles which scavenge cholesterol and return to the liver for recycling and disposal.
TLDR-version: After a meal: blood TG levels spike because chylomicrons are clearing fat from the intestine. Fasting blood TG levels respond to energy requirements via free fatty acids from adipose tissue, and VLDLs from liver.
If the system is working well, TGs disappear into their destinations efficiently, and blood TG levels lower to normal. If the system is consistently overloaded with dietary fats, or confused by lots of sugar-induced insulin, TG blood levels respond by remained elevated and cause trouble in heart and blood vessels, liver, pancreas, kidney and more. How to decrease Triglycerides in your body to optimum levels (less than 150 mg/dL)? There are lots of ways, but the simplest and cheapest are lifestyle choices.
1) Exercise: This burns up extra TG’s floating around and decreases excess levels stored in your adipose tissue.
2) Cooking and eating: Many flavor molecules are fat-soluble which are lost in “fat-free” foods. To makeup for the lack of flavor, processed fat-free foods have sugar added to them to make them more palatable. It’s best to avoid these processed hidden-sugar-laden foods, because type 2 diabetes is risky. Instead, get more creative in the kitchen. Select recipes that are more veggie-forward, discover more pungent and umami-rich ingredients like fermented foods, spices, herbs, mushrooms etc. Instead of frying foods, roast, bake or slow-cook. It’s definitely a life-style change, but one that will benefit your health-span.
3) Drinking and smoking; Decrease alcohol intake and eliminate smoking - both are correlated with increased TGs, metabolic syndrome and morbidity from many causes.
4) Medication or supplementation: Fibrates, Niacin (prescriptions needed) and Essential Fatty Acids somewhat decrease levels of blood TGs.
Essential Fatty Acids (EFA’s) Also called Omega-3s and 6s, these are fats that we get from our diet, most notably fish oils from fish that need insulation in cold water, salmon, sardines, mackerel, steel head trout, cod, (yes, there was a reason for cod liver oil...) as well as flax, walnuts, and leafy green vegetables. The omega nomenclature (biblical reference here, science is not without a sense of humor) tells you how far from the end of the molecule the unsaturated kink is (see the final fatty acid ‘rider’ in the image above). We cannot make these EFA’s in our body and we’ll die without them, hence: essential. They are an important part of cardiac health, vision, inflammation regulation and other important functions. This is why nutritionists are always all over you to eat fatty fish like salmon. If you take the skin off your salmon before you eat it, you are losing much of the oil, so eat the skin! (Salmon skin hint: Grilling makes it even more delicious.) Include these foods in your weekly intake; walnuts, flax, chia seeds, salmon, herring, sardines, oysters, dark leafy greens, pine nuts, Brazil nuts, sunflower seeds/oil, pecans.
Overall takeaway: Balance your fat (triglyeride) intake with lots of healthy food choices, move around to burn off excess energy, eat fish and other delicious foods with EFA’s, and you’ll have solved the fat conundrum, plus you’ll enjoy the wonderful benefits of a healthy heart, liver, pancreas, kidneys and long healthspan.
