The Truth about Fats – not all fats are created equal…
Fats are often touted as “bad” but we need fat in our diet… Fat provides linoleic acid, an essential fatty acid for growth, healthy skin and metabolism. It also helps absorb the fat-soluble vitamins A, D, E and K, maintains cellular health, hormones and brain health.
Fat’s are not all the same, there are trans fats which are man made, saturated fats from animal products, unsaturated fats which consist of polyunsaturated and monounsaturated which also include the essential fatty acids (EFA). Monounsaturated fats are found in olive oil, avocados, nuts and seeds. Polyunsaturated fats can be found in foods such as oily fish, soybean and walnuts.
The best types of fat to include in your diet are the polyunsaturated and monounsaturated fats. Monounsaturated fats are high in Vitamin E and help to maintain or develop cells in the body. Omega-3 and Omega-6 fatty acids are also vital for brain development and the body’s growth.
Both monounsaturated and polyunsaturated fats have health benefits. There is evidence that both types of fats reduce LDL cholesterol levels in the blood when included in a diet low in saturated and trans fats. LDL cholesterol is the ‘bad’ type of cholesterol that increases the risk of coronary artery disease and stroke[i].
Generally ‘bad’ Saturated fats are found in butter, milk, cheese, meat and poultry, however ‘good’ saturated fats are found in coconut oil (lauric acid)[ii].
High intakes of saturated fats can result in elevated LDL cholesterol levels. This can cause fatty deposits to build up in your arteries, causing them to narrow, increasing the risk of blockages. If this occurs around the heart, it can cause a heart attack, and if it happens in the brain it can cause a stroke.
Trans fat is a man made fat that is produced by hydrogenation of vegetable oil (heated at 400 degrees for several hours) with a metal catalyst (aluminium/nickel). When fats are partially hydrogenated this causes a cis double bond conformation and this produces a plethora of unhealthy trans bonds. Unfortunately partial-hydrogenation techniques are the standard technique used.
Trans fats are used because they have a ‘pleasant mouth feel’, give a more solid consistency, and to prolong shelf life. Hydrogenated oil is slow to spoil because, after hydrogenation, there’s nothing biologically active left to spoil… It would be not far from the truth to describe hydrogenated oil as “liquid plastic”.
Found in processed foods such as cakes and biscuits, vegetable shortenings, some margarines, crackers, and snack foods, oils to fry chips and nuggets. Trans fat has no acceptable dietary intake and it is not recommended in any amount.
How to avoid trans fats
The amount of trans fat in food must be declared on the label if a nutrition claim is made about cholesterol, polyunsaturated, monounsaturated fats (omega-3, omega-6 or omega-9 fatty acids).
When reading labels you should seek foods that contain 0 grams trans fat however when a label shows 0 grams trans fat per serving it may contain up to 0.49 grams of trans fat per serving…confused. Trans fats are not always labelled, so, read the labels and watch out for “partially hydrogenated oil” in the ingredients; even if the food claims to be trans fat free.
Therefore, it would be ideal avoid all bakery and packaged foods as there are no guarantees that it contains no trans fat.
Examples of good fats
- Flaxseeds and flaxseed oil
- Seeds such as flax and Chia seeds
- Extra virgin olive oil
- Nuts such as walnuts and almonds
All fats contribute to weight gain via calorie content, so don’t overdo it but don’t avoid it either. Choosing a healthy fat will be lower in calories, just as satisfying and provide the body with some benefit. For example 100g of avocado is 190kcal while 100g potato chips (plain) is 536kcal.
Fat-free means healthy?
A “fat-free” label doesn’t mean you can eat all you want consequence free. Many fat-free foods are high in sugar, refined carbohydrates and calories. Fat should constitute 20-30% of your total calorie intake with the vast majority being from ‘good’ fat sources.
Damaged and rancid fats
A good fat can become bad if light, heat or oxygen damages it. Polyunsaturated fats are the most fragile. Oils that are high in polyunsaturated fats must be refrigerated and kept in an opaque container. Cooking with these oils also damages the fats. Never use oils, seeds, or nuts after they begin to smell, taste rank or bitter.
Points to remember
- Eat mostly unsaturated fats
- Limit saturated fats
- Avoid trans fat as much as possible
- Don’t avoid good fats unless they are rancid
The information contained in this article is based on published nutritional research. It is in no way designed to diagnose or treat specific medical conditions. If you suffer from any chronic health problem; take prescription medication or are pregnant or lactating, please speak to your health professional.
[i] Lada A.T, Rudel L.L (2003) Dietary monounsaturated versus polyunsaturated fatty acids: which is really better for protection from coronary heart disease? Current Opinion in Lipidology: Nutr and met;14 (1):41-46.
[ii] Mensink R.P, Zock P.L, Kester A.D.M and Katan M.B (2003) Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials. Am J Clin Nutr; 77 (5): 1146-1155.