In 1991, the U.S. National Institutes of Health (NIH) launched one of the biggest nutrition studies in history. It was part of the Women’s Health Initiative, a clinical trial and observational study involving 161,808 postmenopausal women. The women were generally healthy and aged 50 – 79 years. The Initiative tested the effects of calcium and vitamin D supplementation, diet modification, and postmenopausal hormone therapy on breast and colorectal cancer, osteoporosis, and cardiovascular disease rates. These are the most common causes of poor health, mortality and disability in postmenopausal women. The Initiative ran for 15 years.
Major Study About Low-Fat Diets
The diet modification study in the Women’s Health Initiative involved 46,835 women. Each one had to maintain a low-fat diet. Half way through the study, it was noted that there was only around a 1-pound difference in weight since the start of the study for most of the women. Further, the rate of cancer, mortality and heart disease remained unchanged! These somewhat surprising facts have been confirmed by other major studies. The consensus? A low-fat diet alone does not reduce the risk of heart disease, cancer or death.
What’s With The Bad Reputation Of Saturated Fat?
So why have saturated fats and oils earned such a bad rap? They’ve been linked for decades with high cholesterol, some types of cancers, heart disease and a myriad of other health problems. A reputation that seems to have stemmed from the knowledge that saturated fat increases total blood cholesterol levels and that high blood cholesterol levels are associated with increased risk of heart disease.
Therefore it was hypothesized, by association, that a diet high in saturated fats must increase the risk of heart disease. This hypothesis entered the annals of public health despite there being no published experimental evidence specifically linking saturated fat with heart disease in humans, and has been accepted as gospel ever since.
Total Blood Cholesterol Level – What Does It Mean?
The fundamental problem with measuring total blood cholesterol levels is that it doesn’t distinguish between good and bad cholesterol. Incidentally, even the terms ‘good’ and ‘bad’ are misleading when applied to cholesterol because cholesterol is just cholesterol. It is transported around the body by proteins called lipoproteins and it is these proteins that are classed as either ‘good’ or ‘bad’.
There are two types of lipoproteins – high-density lipoprotein (good HDL) and low-density lipoprotein (bad LDL). A high level of HDL (high-density lipoprotein) is a good thing to have, as it is associated with reduced risk of heart disease. A high level of LDL (low-density lipoprotein) is not quite so healthy. However, modern science has discovered that even the much-maligned LDL has both bad and neutral forms.
Not All LDLs Are Created Evil
It’s now known that there are 2 types of LDLs. One is a small dense LDL that can get through arterial walls easily and is not good for heart disease. These small LDLs are also susceptible to oxidization and that too has major implications for heart disease. The other type of LDL is larger and doesn’t find it so easy to get through arterial walls. These LDLs are relatively harmless.
Studies have also shown that it’s people with a high concentration of small LDLs who are more at risk of getting heart disease. Three times more at risk in fact than those who have a high concentration of large LDLs and a low concentration of small LDLs. So the take home message is simple – to reduce your risk of heart disease you need to have large neutral LDLs rather than small dense LDLs! Or few LDLs period.
Saturated Fat And Small LDLs
Whilst saturated fat does raise LDL blood levels, an interesting thing is that it appears to change harmful small LDLs to large neutral LDLs. By implication therefore it would appear that if you reduce your intake of saturated fat too much, you could actually be doing yourself more harm than good! Especially if you do happen to have a high concentration of small dense LDLs in your blood stream.
But Wait…. There’s More!
Some fatty acids do not raise LDL levels whilst others do. This propensity to raise blood level concentrations of LDL, or not, is now thought to be linked to the number of carbons a fatty acid has (ie its ‘chain length’).
Another factor that comes into play when determining the whole healthy cholesterol level issue is the number of LDL particles (LDL-p) in the blood. High LDL-p is believed to be more harmful than low LDL-p. Interestingly, low-carb diets seem to lower LDL-p, even though they may be relatively high in saturated fats. Conversely, low-fat diets can have the opposite effect and increase LDL-p.
Saturated Fats – Debunking A Few Misconceptions
Saturated fats not only help ‘neutralize’ LDLs by changing them from harmful small dense particles to mostly harmless large LDL. They also raise HDL blood levels, something that is reasonably well known but often ignored! So overall, saturated fats are nowhere near as harmful to the blood lipid profile as was previously assumed.
Saturated Fats And Heart Disease Death Rates
Studies are also increasingly finding that reducing consumption of saturated fats has very little or no impact on the rate of deaths caused by heart disease. However, what they are finding is that replacing saturated fats with unsaturated fats reduces cardiac events AKA heart muscle damaging incidents, by 14%. Even so, this doesn’t mean, or prove, saturated fats are bad. It’s just that unsaturated fats like Omega-3s tend to have protective benefits where saturated fats are neither harmful nor protective.
Saturated Fats – They Are An Important Component In A Healthy Diet
Including some saturated fat in your diet has plenty of other benefits too! Good quality, unprocessed foods like coconut, dark chocolate, grass fed dairy products and meat are all high in natural saturated fats and are very nutritious and healthy. Not to mention very tasty!
Due to their structure, saturated fatty acids are also very stable when it comes to heat. Where polyunsaturated fats have 2 or more double bonds and monounsaturated fats have 1 double bond, saturated fats have no double bonds. This makes saturated fats very resistant to heat damage. Saturated fats like coconut oil, butter and lard are therefore great for cooking and frying. Unlike polyunsaturated fats that oxidize readily when heated.
Not All Fats Are Created Equal
The world is full of numerous varieties of fat! And not all fats are created equal. Some fats are very bad for your health whilst others are beneficial. Some, like saturated fats, are neutral. The fats that are OK to include in a healthy diet are monounsaturated and saturated fats. These types of fats have proven health benefits and as part of a balanced diet, do not cause any harm.
Polyunsaturated fats are also generally beneficial albeit a bit more complex because Omegas 3 and 6 are both polyunsaturated fats. We need both these in balanced proportions as part of a healthy diet. Fish in particular is noted for being an excellent source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) Omega 3s. Alpha linoleic acid is an alternative form of Omega 3 fat found in oils made from canola, flax seeds, hemp seeds and chia seeds. Walnuts and soybeans are also high in ALA. For vegetarians and vegans, these foods should play a very important part in their diet.
Omega 6 – Not So Beneficial After All
The popularity of seed and vegetable oils, particularly corn and soy, which are high in Omega 6 fatty acids, means that for many people the fine balance of Omegas 3 and 6 gets way out of whack. When this happens, it pushes Omega 6 fats from beneficial into the not so beneficial category as they’re known to be pro-inflammatory. Cutting back on the use of high Omega 6 fatty oils for cooking and in food products will help redress this imbalance. As will increasing the amount of Omega 3 rich foods consumed.
The Fat You Really Should Be Avoiding!
Most people are aware of artificial trans fats, or they should be! This is a man-made fat produced by adding hydrogen to polyunsaturated vegetable oils so it becomes solid. And as with many man-made vs natural products, it is rapidly proving to be almost toxic. Excessive consumption of trans fat has been linked to many of the same things that saturated fat has traditionally been blamed for! The difference though is that there is hard cold evidence to back up the harmful effects of trans fat. Effects like dangerous belly fat buildup, heart disease, insulin resistance, inflammation and more.
So to sum up – feel safe to include monounsaturated and quality saturated fats as part of a healthy balanced diet. Be careful with polyunsaturated oils, especially Omega 6 as excessive consumption of this fat can be detrimental. And avoid artificial trans fats whenever possible as this fat is bad news.