Guest blog by Vicky Ware
Can We Eat as Much Saturated Fat as We Like?
There have been headlines about saturated fats in the news lately – many suggesting that saturated fats are not actually bad for us. This is because a new study was published claiming that the dietary advice in the 1980s to lower intake of saturated fat was not based on good evidence 1.
Although the new study has some good points, it wasn’t without flaws and its results don’t mean we can all eat as much saturated fat as we like without an impact on health. Saturated fat comes from many different sources and these have different effects on health. It all comes back to getting the right balance between different types of fat in our diet.
How Much Saturated Fat Should We Eat?
One complication is that ‘saturated fats’ encompass a range of different fats and each of these is packaged in a different type of food – dairy products have a different effect on your body than red meat, for example, but they both contain saturated fat.
The nutrition guidelines in the UK recommend men eat no more than 30 grams of saturated fat a day and women eat no more than 20 grams 2.
The foods that we’re advised to keep to a minimum are fatty cuts of meat (not including fish) and dairy products – butter, cheese, cream, some savoury snacks, chocolate confectionary and cake. The saturated fat in all of these foods is mainly from dairy 2.
The UK nutrition advice is quite conflicting as the ‘eatwell plate’ has a significant section devoted to milk and dairy foods, and a large section for ‘meat, fish, eggs and beans’ as sources of protein 3.
The dietary advice is to cut down on red meat and dairy, but they word this as cutting down on ‘saturated fats’.
Studying how the foods we eat impact our health is really complicated because there are so many factors involved. Looking at populations can give us a pretty good idea of whether eating a certain way is good for us.
In 1960, 45% of the American diet was from fats and oils, around 13% of the population were obese and less than 1% had type 2 diabetes. Now, Americans eat less fat at 33% of their daily intake – however 34% are now obese and 11% have diabetes 4. It seems that dietary fat is not the cause of obesity and type 2 diabetes because when people ate more of it, the population as a whole were slimmer and less likely to get diabetes.
Some populations in the world eat diets very high in fats – even saturated fats from plant and marine sources but have little or no sign of heart disease 5;22. The Mediterranean diet is well known for being healthy and contains lots of fat 6.
It’s All About Balance
It’s not the amount of fat you eat but the balance of different fats in your diet.
When the 1980s advice to lower saturated fat intake came out, as a population we replaced the fats in our diet with sugar.
Unfortunately, it has since been shown that over time a diet high in easily digestible carbohydrates such as sugar is worse for heart health than eating a poor balance of fats 7.
So it’s important to replace bad fats with good fats, not with easily digestible carbohydrates.
One of the reasons eating lots of saturated fat without a balance of other fats is bad for health is because they increase cholesterol in the blood if not eaten in a diet that contains good fats. Cholesterol is crucial to virtually every process in the human body because our cells are made from it. Our bodies can make cholesterol out of other foods we eat.
It is cholesterol in the blood stream (rather than being stored in the liver, or used to make cells) that negatively affects health – and how much is in the blood is affected by the balance of fats we eat much more than how much cholesterol we eat 8.
Good Fat, Bad Fat and Cholesterol
Fat such as cholesterol can’t dissolve in water, just like oil won’t dissolve in water but rather clumps together in droplets. This means fats can’t dissolve in blood either and need a ‘chaperone’ to transport them. Cholesterol is transported out of the liver and into the blood by low density lipoprotein (LDL) – think of LDL as a one way tram service out of the liver.
Excess cholesterol is transported back to the liver for storage by high density lipoprotein (HDL) – HDL being the tram back home. The tram lines can’t be moved – LDL takes cholesterol out, HDL brings it back.
The foods you eat affect how much LDL and HDL you have in your body. The typical Western diet tends to mean we have enough LDL (getting cholesterol in to our bloodstream) but not enough HDL to bring the cholesterol back.
If there is too much cholesterol in the blood stream, attached to LDL, it can end up burrowing into artery walls where it sets up an inflammatory response and ultimately causes heart disease.
The more HDL in your body, the lower your chance of having arteries clogged with cholesterol 9.
So, it’s not about reducing the amount of fat we eat but eating the right kind of fat.
Foods that increase our HDL are also associated with good heart health, as well as with reducing onset of some kinds of cancer. These are often polyunsaturated and monounsaturated fats but some saturated fats improve the ratio of HDL to LDL in the blood too – although these are usually from plant not animals sources 10;11.
It is because this ratio between HDL and LDL is so important that eating a low fat diet isn’t going to improve your health – you’ll be cutting back on LDL along with the HDL 10. It is also why people who exercise a lot can still have high cholesterol. Exercise does have some impact on blood cholesterol levels, but the biggest impact is the balance of fats in your diet.
Along with increasing HDL, we also want to decrease inflammation in our body. A large factor in many diseases of Western culture – including heart disease as we describe earlier – is chronic inflammation.
Eating fat is essential for a diet that does not promote inflammation – nuts and seeds along with oily fish and fats from olive oil and avocado are all key to a low inflammation, heart healthy diet 12;13;14.
Trans Fats are Bad Fats
It’s true that butter is better for you than the margarines of the past, which contained high levels of trans fats – also known as hydrogenated fat. These artificially produced fats were worse for health than the saturated fats in butter. Trans fats are not just artificially produced but are naturally present in meat and dairy in small amounts.
A study found that women who ate 4 teaspoons of margarine a day had 50% more risk of heart disease than women who only ate margarine every now and again 15.
Trans fats not only raise LDL (transporting cholesterol into the blood stream) but also increase inflammation 16.
Every time trans fats contribute 2% to your diet, your risk of coronary heart disease goes up by 23% 16. Happily, far fewer foods now contain trans fats and most supermarkets have taken them out of their own brand foods. If a food does contain hydrogenated fat, it must say so in the ingredients.
Long Term Studies
An eight year trial looking at just under 50,000 women found that those who followed a low fat diet had virtually identical rates of heat attack, stroke and other types of heart disease as those who didn’t. They didn’t lose any weight either 17;18. It was the type of fat, not the amount of fat which affected health 19.
Yet again it comes back to balance – this time getting a balance between the right kinds of fat.
- Eating too much refined carbohydrate and sugar is as bad for health as getting the wrong balance of fats in your diet.
- It is the balance of fats not the amount of fat which affects health.
- Your body needs saturated fats and cholesterol for health.
- Too much cholesterol in the blood stream is bad for health.
- Your body can make cholesterol, it’s the balance of fats which affects whether this cholesterol is in your bloodstream rather than whether you eat cholesterol.
- Cutting back on saturated fats found in meat and dairy products is good for health IF you replace those fats with good fats not carbohydrates 20;21
- When eating red meat and dairy try to get grass fed meat which has a better balance of fats.
So we can’t just eat as much saturated fat as we like without expecting an impact on our health. However, so long as we’re getting a good balance of fats in our diet eating saturated fats doesn’t seem to be as bad for health as experts once thought.
Vicky has a degree in Biological Sciences with a focus on biochemistry and immunology and is currently studying for a MSc in Drug Discovery and Protein Biotechnology. She is also an endurance athlete.
Want some more detail on saturated fat? Try these previous posts: The Truth Behind Saturated Fat, The Truth About Saturated Fat – An Update and here’s another post by Vicky on inflammation, Inflammation and its Effects.
- Harcombe, 2015. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis.
- NHS Saturated Fat, 2015. http://www.nhs.uk/Livewell/Goodfood/Pages/Fat.aspx
- NHS Eatwell Plate, 2015. http://www.nhs.uk/Livewell/Goodfood/Pages/eatwell-plate.aspx
- The Nutrition Source, Harvard, 2013. Fats and Cholesterol: out with the bad, in with the good. Harvard School of Public Health.
- Gadsby, 2004. The Inuit Paradox.
- Casas, 2014. The immune protective effect of the Mediterranean diet against chronic low-grade inflammatory diseases
- Hu, 2010. Are refined fats worse for health than saturated fat?
- Fernandez, 2006. Dietary cholesterol provided by eggs and plasma lipoproteins in healthy populations.
- Barter, 2004. Anti-inflammatory properties of HDL.
- Mensink, 2003. Effects of dietary fatty acids and cabohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials.
- Akkinuga, 2014. Dietary consumption of virgin coconut oil ameliorates lipid profiles in diabetic rats.
- Ellulu, 2015. Role of fish oil in human health and possible mechanism to reduce the inflammation.
- Ownby, 2014. Expression of pro-inflammatory mediators is inhibited by an avocado/soybean unsaponifiables and epigallocatechin gallate combination.
- Salvado, 2014. Nuts in the prevention and treatment of metabolic syndrome.
- Willett, 1993. Intake of trans fatty acids and risk of coronary heart disease among women.
- Mozaffarian, 2006. Trans fatty acids and cardiovascular disease.
- Howard, 2006. Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial.
- Howard, 2006b. Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomised Controlled Dietary Modification Trial.
- Hu, 2001. Types of dietary fat and risk of coronary heart disease: a critical review.
- Siri-Tarino, 2010. Saturated fatty acids and risk of coronary heart disease: modulation by replacement nutrients.
- Astrup, 2011. The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010?
- Prior, 1981. Cholesterol, coconuts, and diet on Polynesian atolls: a natural experiment: the Pukapuka and Tokelau Island Studies.
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