This is probably one of the topics that makes dietitians feel all sorts of things. In my experience, it has been a topic where there are many different schools of thought; some are well-researched, others are less researched and some have little to no reputable research to back them up. In truth, a Dietitian’s nightmare.
When I was practicing in SA, I would dread the ‘fat’ question as I knew I was about to face a head-on battle with over-the-top fad diets and the people that promote them like a religion. I would stand at a barbecue (‘braai’ for the South Africans) and await a comment about how we should all add butter to our coffee as it has all these good fats and will stop heart disease. I would cringe watching a housemate deep fry her bacon with butter, while she told me that it was helping her lose weight. I believe that this is not the fault of the ‘messenger’ but rather that of public figures; and untrained voices, websites and publishing houses for sending mixed messages to the population.
In this (hopefully) brief article I hope to simplify fats for you and equip you with knowledge so that you can make the healthy choice for YOU and be able to distinguish between fad and fact.
Fat has been demonised in the past for causing heart disease (HD). In truth, certain fats can increase the risk of HD and stroke but certain fats can also reduce the risk of these incidents if had in moderation.
Physiologically speaking, dietary fat is turned into cholesterol (and many other molecules) by the liver. These cholesterol molecules travel around the blood vessels and are responsible for certain functions. There are 3 main types of cholesterol made be the liver (we will use the acronyms): LDL, HDL and VLDL. We will talk about LDL and HDL. Let’s start with LDL and let’s picture it as a car. The car moves around the blood vessels and crashes into other cars, these ‘crashes’ pile up in the blood vessel until there are so many in one place that it causes the road to narrow until it’s completely blocked. The crash here is a ‘plaque’ which can lead to a heart attack when it blocks the vessel completely. Now, HDL is like an ambulance, tow truck and police van – they circle the blood vessels and collect as much of the car crashes as they can to take them back to the liver. Thereby reducing the risk of heart disease and other vascular events (e.g. stroke when the plaque is dislodged and moves to the brain as a clot). It is for this reason that we want more of the good, HDL in the blood than the bad, LDL. Although cholesterol levels can be influenced by genetics and other factors, diet plays a crucial role in the prevention of heart disease.
Healthy fats are those that reduce the risk of heart disease. Foods that contain these fats should replace foods with unhealthy fats. Healthy fats should also be eaten in moderation like all things in a balanced diet.
There are two categories of good fats; monounsaturated and polyunsaturated.
Monounsaturated fats (MUFA) have been found to reduce LDL levels in the blood when replacing bad dietary fats. They are liquid at room temperature and tend to harden as they cool.
Polyunsaturated fats (PUFA) are fats like omega-3 and omega-6. These are essential fatty acids which means the body can’t make them alone so they need to be taken in through the diet. They have similar benefits to MUFA, with omega-3 having the added anti-inflammatory function. PUFA have been found to reduce LDL while increasing blood HDL. So, more ambulances and less car crashes.
These HEALTHY fats can be found in the following foods
The basic rule is to get your fat from plants with some exceptions.
- Avocado and oil
- Olives and olive oil
- Peanuts, peanut butter
- Nuts and seeds
- Sesame seeds and oil
- Soybeans, soybean oil, tofu
- Sunflower oil
- Rapeseed oils
- Flaxseeds and oil
- Walnuts, sunflower seeds
- Oily fish (mackerel, salmon, tuna) – one exception to the ‘plant fat only’ rule
Unhealthy fats are those that increase the risk of heart disease, stroke and even type 2 diabetes mellitus. They do this by increasing factors such as LDL and decreasing HDL. Every country has different recommendations on daily intake of these fats, so I’ll just stick to general guidelines.
There are two categories of unhealthy fats; saturated fats and trans fats.
Saturated fat (SFA) is the fat that is under a lot of debate at the moment – health professionals without nutritional training have written books about how it’s not responsible for heart disease, others with no health training or research are writing blanket, controversial recommendations for people on websites. So what’s the truth? Copious amounts of research has found a correlation between SFA intake and heart disease risk (AHA, 2015). Research has been reviewed and similar results found over and over again. The more SFA you eat, the more at risk you are for heart disease. This is because SFA intake increases the amount of LDL produced by the liver, and therefore more ‘crashes’ in the blood vessels.
The last fat, there is absolutely no debate, is without a doubt the worst for your health. Trans fats (TFA) not only increase LDL in your blood but reduce HDL. So a lot more car crashes and a lot less rescue operations. These fats are made naturally in some animal guts and can find their way into your food in this way, but the main source is through artificial production as hydrogenated plant oils. Plant oils are hydrogenated to make them more solid and easier to use.
These UNHEALTHY fats can be found in the following foods
The basic rule is to avoid commercially produced fried/baked foods and animal products that are high in fat.
- Meat – beef, pork, lamb, poultry skin
- Dairy – milk, butter, cheese, lard
- Tropical plant oils (the exception!) – palm oil, palm kernel oil and coconut oil
- Fried foods (commercial) – donuts, fries, etc
- Baked goods (commercial) – cookies, crackers, cakes
- Hard margarine (all are made with hydrogenated plant oils)
Here are my top tips for helping your heart and eating healthier fat wise:
- Cook from scratch with the freshest ingredients and with moderate amounts of healthy fats.
- If looking for a snack that you would usually buy commercially, try making it at home yourself (homemade popcorn, whole grain muffins, cookies) with oil that you know has healthy fats.
- Choose nuts and seeds as a snack.
- Replace butter or hard margarine with avocado or peanut butter as a spread on wholewheat bread.
- If putting a spread on bread, have a 1 fat layer rule – e.g. if you want avocado toast, only have the avocado.. do not have margarine/butter and then avocado on top.
- If you include dairy in your diet, opt for reduced fat versions of milk, yoghurt, cheese.
- If you include meat in your diet, try buy lean cuts and trim off any fat you can. Always remove skin from poultry before cooking it.
- Always choose plant oils except for tropical oils like coconut and palm.
- Remember Sal (previous post); don’t listen to her. Refer to registered nutrition professionals and sites to get evidence-based information.
- American Heart Association, https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats
- British Dietitian Association, https://www.bda.uk.com/foodfacts/home
- Australian Dietitian Association, https://daa.asn.au/smart-eating-for-you/smart-eating-fast-facts/healthy-eating/whats-the-best-type-of-fat-for-a-healthy-heart/
- Harvard Health (image)