There is so much confusion over ‘fat and cholesterol’ in the media that it’s no wonder people are bamboozled. Here are some definitions and explanations to help you understand.
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main functions of lipids are storing energy, cellular signaling, and acting as structural components of cell membranes.
Lipoproteins- HDL and LDL: Ever seen oil floating in water? Because our bodies are mostly water we need transporters to move lipids around our bodies so they can move through our bodies easily. These transporters are called lipoproteins. There are five types but LDL and HDL are the ones we hear about most often. They are often referred to as ‘good and bad cholesterol’ although they are not cholesterol.
HDL: (High density lipoproteins) are good because they transport lipid particles from the artery walls back to the liver. There is no magic pill that will increase HDL but there is some evidence for boosting your HDL levels by exercising, increased intake of soluble fiber, smoking cessation, weight loss, and increasing omega 3 consumption.
LDL: (Low density lipoproteins) are ‘bad’ because they transport lipids (like fat and cholesterol) out to the artery walls where they cause plaques (build up) causing atherosclerosis (thickened arteries) and can rupture causing heart attacks.
Cholesterol is a type of lipid containing sterol. Cholesterol forms animal cell walls and plays an integral part in the synthesis of steroid hormones and bile acids, and vitamin D formation. Our bodies make all the cholesterol we need, which means we don’t need any from our diet. The good news is that cholesterol is only found in animal products. Therefore eating a plant based diet means you will be eating cholesterol free all the time!
Fats are a subgroup of lipids called glycerides.
Glycerides comprises of glycerol with fatty acids attached
Fat has a bad name. New nutritional guidelines were influenced by the American 1977 McGovern committee report and the 1982 National Academy report which both recommended to lower our consumption of fat to aid in the reduction in cardiovascular disease and cancer.
Suddenly the food industry was making a new set of products, ‘fat free’ and ‘99% fat free’ and ‘now with less fat’. We look back now with rising obesity rates and wonder why all our careful fat avoidance continued to worsen our health. The problem was that taking fat out of food makes it taste bland so everything was topped up with extra sugar, more animal proteins and sneaky tricks.
99% fat free milk has 2g of fat for every 200ml serving
This is equivalent to 18 calories a serve. (1g fat= 9 calories)
The total calories in a serving of milk is 81 calories.
Therefore 18/81 x100 = 22%.
Therefore when drinking your 99% fat free milk, 22% of the calories you are drinking are from fat. Why is this? Because adding water to milk makes it heavier, if you work out the fat per weight (which the milk company likes to do) if looks a lot less. Very sneaky indeed.
Fat like carbohydrates is used for fuel by the body and can store energy for later use (and insulation). Fat is also an essential component in cell membranes and used to make hormones in the body and absorb fat dependent vitamins. Animal fats are predominantly saturated fats where plant fats are predominantly unsaturated. Fatty acids are the basic components that make up fat.
Fatty acids
These fatty acids differ in structure and are grouped into 3 categories.
Monounsaturated
Structurally these only have one double bond. Examples are :olive oil, canola oil, avocados and nuts.
Polyunsaturated
The chemical structure has more than one double bond. For example: vegetable oils, grains, legumes, some nuts.
There are two essential fats in the human diet - these are Omega 3 (alpha-linolenic acid) and Omega 6 (Linolenic acid)
- Omega 3 rich foods are flax seeds, chia seeds, hemp seeds, walnuts, canola oil and some soy foods
- Omega 6 rich food are sunflower, corn and soy oil
Saturated fat
Chemically has double bonds. Most animal fats and some plant fats such as coconut, palm oil and chocolate.
Trans fats
In food production unsaturated plant fats are ‘hydrogenated’ to make saturated fats which have more desirable qualities e.g harder consistencies and melting points. Hydrogenation is adding hydrogen atoms to change the double bonds of unsaturated fats to single bonds of saturated fats. During this process, some molecules have bonds on the wrong side, causing the structure to twist and create trans fats- a by-product of the hydrogenation process. Trans fats are thought to be detrimental to health and increase cardiovascular risk among other adverse health effects. The FDA in 2013 stated ‘hydrogenated oils (which contain trans fats) are not generally recognized as safe". Trans fats are naturally found in small amounts in animal products but due to hydrogenation of plant oils are now found in processed foods such as snack foods, fried foods and baking.
Omega 3 and 6
There is a lot of publicity around omega 3 and 6. With Omega 3 marketed as the hero, many people take omega 3 supplements in the form of fish oil. A review in 2006 looking at 59 papers on omega 3 supplements concluded that “Long chain and shorter chain Omega 3 Fats do not have a clear effect on total mortality (how long you live), combined cardiovascular events, or cancer.” Another major study in 2009 involving 9,380 cases and 3 million person years of follow up, found a statistically significant rise in type 2 diabetes associated with supplementation of Omega 3.
The evidence would suggest the ratio of omega 3 to omega 6 in our diet that is most important aspect. Omega 3 having anti-inflammatory properties and omega 6 pro-inflammatory. The current recommendations is to have a ratio of 3:1 of omega 6:omega 3. The typical western diet has a ratio of around 20:1 while a plant based diet is more along the lines of 3:1 or 2:1.
Tips around fat in your diet
Keep your fat intake at a moderate-low range
Avoid saturated and trans fats
Choose fats that are mono-saturated and those high in omega 3 like chia seeds, linseeds and walnuts.
Boost your HDL levels by exercising, quitting smoking, increasing omega 3 foods in your diet and eating more fiber.
Avoiding food from animals your diet will be cholesterol free!