The Low-Fat Fallacy: Part 3 – The Benefits of Saturated Fat

Exploring the many benefits of saturated fat

So are you still afraid of fat and saturated fat? It would not be surprising after 6 decades of misinformed public health policy promoting the low-fat diet.

In the previous post of this series I described the importance of essential fatty acids and of fats in general for the brain, for cell membranes and thus for our evolution as multicellular organisms. In this post I will focus more on the benefits of saturated fat.

Saturated fats for infant development

If saturated fats were universally bad for us they would not form part of the natural human diet unless evolution has somehow got it wrong or has at least made some kind of a compromise. In the first post of this series I described the high animal fat intake of hunter-gatherers and the absence of heart disease in that population. Yet even in the industrialised world saturated fats form 50% of breast milk and seem to be essential for the rapid stages of growth and development such as during infancy, since saturated fats are required for cell membranes and lipoprotein (1) to transport fat, cholesterol and fat soluble micronutrients around the body. The misguided focus on saturated fat as the cause of heart disease has resulted in a dearth of research into the beneficial effects of specific saturated fats despite there being a wide spectrum of saturated fatty acids of different chain lengths in breast milk (2) and yet the evidence we do have suggests that saturated fats have many health benefits.

Babies are born with very permeable guts and breast milk is known to carry many components vital for the infant’s healthy gut and microbiome development, such as oligosaccharides, lactoferrin and defensins. Similarly the short chain fatty acids in breast milk, which are all saturated fats, also function to keep inflammation down and help to seal the leakiness of a baby’s gut (3). Interestingly the saturated fats in milk also increase HDL lipoproteins (4) which protect against the bacterial endotoxins that could more readily penetrate a leaky gut wall to then cause systemic inflammation (5, 6, 7).

Saturated fats in adult health and wellbeing

As an adult your gut microbiota also generate (saturated) short chain fatty acids such as acetate, propionate and butyrate from dietary fibre which has multiple health benefits. So fibre is not good for you just because it acts as a bulking agent, as was previously believed, but because it helps you make saturated fat that benefits gut health (8), protects against inflammation and cancer (9, 10), Inflammatory Bowel Disease (11), obesity (12) and type 2 diabetes (13), benefits immune function (14), and helps to regulate blood pressure (15, 16).

The short chain fatty acid butyrate is so named because it is found in butter. It is the primary fuel for the cells lining the wall of your large intestine (17), helps to fight candida overgrowth (18) and to regulate inflammation (19) and may regulate neurotransmitter production (20) and benefit depression, neurodegenerative conditions and cognitive impairment (21) as well as reduce the risk of colon cancer (22). The conversion of fibre into butyrate occurs in the large intestine but consuming butter can provide butyrate to the small intestine where it can reduce inflammation and even improve small intestinal health in people with Crohn’s disease (23). Oral butyrate consumption improves insulin sensitivity, promotes mitochondrial function and increases energy expenditure in mice (24).

Your gut flora also make long chain saturated fats that may help to prevent intestinal permeability (a.k.a. ‘leaky gut’) and hence to protect from the increase in the absorption of bacterial endotoxins that causes alcoholic liver disease. Supplementing these saturated fats therefore offers protection against alcoholic liver disease, at least in mice (25). If this research translates to humans it seems likely that these saturated fats will also protect against many of the other conditions associated with bacterial endotoxins, such as heart disease, obesity, type 2 diabetes (26), chronic fatigue syndrome (27), depression and anxiety (28).

The benefits of specific saturated fats

Saturated fats such as caprylic acid, capric acid and caproic acid are so named because goat’s milk is a rich source (goat is caper or capra in Latin, depending on gender), and the medicinal value of goat’s milk is attributed to these fatty acids, which preliminary research suggests are protective agains cancer (29). These fatty acids are also found in human milk and have antimicrobial and antiviral properties (30, 31). Caprylic acid is often used in antifungal supplements but both capric and caprylic acids can be effective against candida overgrowth (32).

Lauric acid is a (saturated) medium-chain triglyceride found in coconut and in breast milk that is showing even more potential in protecting from colorectal cancer than butyrate (33). Lauric acid is also antiviral (34) and can work in synergy with other saturated fatty acids to increase its antibacterial properties (35). Lauric acid and the monolaurin it is partly converted to in your body may protect against the stomach bacterium Helicobacter pylori (36). Monolaurin is also anti fungal and can help to break down candida biofilm (37). Moreover these fatty acids are both much less likely to cause bacterial resistance than antibiotics (38, 39) and lauric acid even shows activity against MRSA (40), a common cause of antibiotic resistant infection acquired in hospital.

Palmitic acid and stearic acids are the most common saturated fatty acids in animal fat. Stearic acid and also lauric acid reduce the total cholesterol to HDL cholesterol ratio, thus reducing heart disease risk (41). Palmitic acid, also found in in breast milk, increases the absorption of calcium (42) which is vital for bone health. Both palmitic acid and myristic acid, another saturated fatty acid, play key roles in the regulation of nitric oxide production to dilate blood vessels and maintain healthy blood pressure (43).

The science behind fats

Now for some basic chemistry which can help illuminate some key differences between saturated, monounsaturated and polyunsaturated fatty acids and why saturated fat can be part of a healthy diet. Each atom has the potential for forming a certain number of bonds with other atoms and a collection of bonded atoms forms a molecule.

A hydrogen atom can form one bond to just one other atom, an oxygen molecule can form two bonds to two other atoms and a carbon atom can form four bonds and has a tendency to bond with four other atoms. Each straight line in the diagram below represents a single bond.

When a carbon atom in a hydrocarbon chain bonds with three other atoms and forms what is called a ‘double’ bond with another carbon atom there is a tendency to react with some other atom so that the carbon atoms can become ‘saturated’ by each having four distinct ‘single’ bonds satisfied with four distinct atoms. The double bond is shown by a double line in the diagram below.

A fatty acid is a chain of carbon atoms attached to hydrogen atoms with a ‘carboxyl’ group at one end of the chain. A fatty acid is ‘saturated’ when each of the carbon atoms in the chain is bonded with four other atoms, except for the carbon at the end in the ‘carboxyl group’ which shares a double bond with an oxygen atom. No more reaction can easily take place from the single bonds so the molecule is stable.

A polyunsaturated fatty acid (PUFA), on the other hand, has more than one unsaturated bond between carbon atoms in the chain. These carbons are therefore very reactive and the fatty acid is unstable and easily oxidises to form inflammatory lipid peroxides (44, 45).

Monounsaturated fatty acids have just one unsaturated bond between carbon atoms in the hydrocarbon chain and are more stable than polyunsaturated fatty acids but not as stable as a saturated fatty acid.

Saturated fats tend to be solid at room temperature because they are straight molecules and stack together. A double bond bends the fatty acid so that rather than stacking in neat rows polyunsaturated fats tend to be liquid at room temperature, as do monounsaturated fats.

The increased stability of saturated fats leads to a longer shelf life (46) and is the reason why coconut oil is one of the safest oils to cook with, though in fact extra virgin olive oil may be even safer due to the polyphenols protecting the primarily monounsaturated fatty acids (47). Saturated fat is also more stable in the body whereas if oxidised even omega-3 fatty acids from fish oil can have an adverse impact on your health (48) and may even contribute to cancer (49). Perhaps this reactivity explains the mixed results in studies of fish oil on health outcomes where the negative outcomes might result from too much fish oil (50), and why more success is seen when polyphenol-rich extra virgin olive oil is also included in the diet (51), since polyphenols have an antioxidant effect in the body and protect fatty acids from oxidation (52, 53). Some research does suggest that although omega-3 fatty acids are easily oxidised as oils kept in storage they may also have an anti-oxidant effect in the body, unlike omega-6 fatty acids (54).

Polyunsaturated fatty acid instability and the harmful effects of lipid peroxides

As we have already seen, PUFAs, with the possible exception of omega-3 fatty acids in the body, are more readily oxidised to form lipid peroxides and these can damage lipids, proteins and carbohydrates in the body and can oxidise cholesterol (55). Lipid peroxides damage cell membranes and block enzyme function in the cell membranes thus causing cell and tissue damage (56) and have been linked with many conditions including heart disease, diabetes, cancer and accelerated ageing (57).

PUFA instability contributes to the vulnerability of your central nervous system to degeneration due to the high levels of PUFAs accumulating in cell membranes, especially with low levels of antioxidant protection, and can therefore play a role in Alzheimer’s disease, Parkinson’s disease and stroke (58). Could the stability of saturated fat displacing less stable PUFAs and protecting the nervous system be the reason for the association of increased saturated fat intake with reduced risk of stroke in the 2017 PURE study (59) I introduced in part 1 of this series?

Now as you know cholesterol has been blamed for heart disease. Cholesterol, fats and fat-soluble micronutrients are carried around the body in lipoproteins because in themselves they are not water-soluble. It is the oxidation of the LDL particles that increases the risk of atherosclerosis (60) and the components of the LDL particle most susceptible to oxidation are the PUFAs, so it may well be that increasing the more stable saturated fat whilst decreasing PUFAs may be protective. Indeed omega-6 PUFAs increase LDL oxidation when compared to monounsaturated fatty acids, and much of the research even implicates omega-3 fatty acids in LDL oxidation (61) so too much fish oil might in fact be counterproductive. Plaque in the aorta has been found to contain PUFAs in proportion to dietary PUFA intake as reflected by adipose tissue stores, but the same association was not found for saturated fatty acids, and this finding may reflect a role of dietary PUFAs rather than saturated fatty acids in atherosclerosis (62). Omega-6 PUFA linoleic acid in fat tissue and platelets is linked with heart disease, and is the most commonly oxidised fat in LDL particles, and may therefore be a key driver of heart disease (63).  The high stability of saturated fat may explain why a high saturated fat diet improved the survival rate in guinea pigs with heart failure relative to both a low-fat diet and a high PUFA diet (64).

Saturated fat stability may also be why the mitochondria in the hearts of rats showed the least oxidative stress when fed with primarily saturated fatty acids in the form of coconut oil in comparison to primarily polyunsaturated fish oil and monounsaturated olive oil. In this study it was the fish oil that caused the most oxidative stress of the three foods and the damage could be reduced by the use of antioxidants (65) and so saturated fat may in fact be the preferred fuel for the heart (66). 

This could be an important preference because generating ATP, the body’s currency of energy, generates oxidative stress which can overwhelm compromised antioxidant defences to damage mitochondria. This process may be crucial in the brain as it is the most energy intensive organ of all and the resulting oxidative stress increases its vulnerability to neurodegenerative disease (67). The heart is also very rich in mitochondria to support its lifelong mission of pumping blood around your body to keep you alive and is thus particularly vulnerable to oxidative stress (68). Since specific saturated fats may benefit heart health, reducing saturated fats in general may actually increase the risk of heart disease, especially when replaced with refined carbohydrates (69). 

The link between energy demand and oxidative stress may be why Alzheimer’s disease and cardiovascular disease are amongst the great epidemics of our time, along with obesity and Type 2 diabetes (caused largely by low-fat high carbohydrate diets). The blood sugar spikes that result from a high carbohydrate diet have been proposed to cause the damage by overloading the mitochondria to cause high levels of oxidative stress (70) whereas the benefits of the very low carbohydrate or ketogenic diet on not just obesity and diabetes but also for Alzheimer’s and Parkinson’s disease may be in part due to reducing oxidative stress by providing an efficient and clean fuel for the mitochondria in the form of ketones that are made from dietary fat (71).

These effects on oxidative stress both in LDL lipoproteins and in heart mitochondria may partly explain why replacing saturated fat with linoleic acid in the Sydney Diet Heart Study increased both heart disease and all-cause mortality (72), though being an omega-6 fat would also make linoleic acid proinflammatory when consumed in large quantities (73). The increased stability of saturated fat may also explain why higher saturated fat to PUFA ratios are more protective against cancer in mice (74). Lower saturated fat intake and higher PUFA intake is also associated with reduced fertility in women (75).

Could the association of reduced wrinkles with saturated fat intake in Japanese women also be due to the stabilising effect of saturated fat, especially since yellow and green vegetable intake was also associated with reduced wrinkles, presumably due to antioxidant effects (76)? It is also interesting to note that cholesterol in topical creams protects against damage to skin from ultraviolet radiation whereas linoleic acid, being a polyunsaturated fatty acid and thus reactive, aggravates the damage (77).

Redressing the balance – PUFAs and saturated fats

I am not intending to demonise PUFAs in this article but simply to shift the balance from seeing saturated fats as more harmful than PUFAs. In the previous post I described some of the essential functions of PUFAs. Saturated fats may stabilise PUFAs in the body but the readiness of PUFAs to oxidise could cause them to be burned for energy more easily than saturated fat (78) and some evidence indicates that dietary PUFAs increase the oxidation of saturated fat for energy (79) though other research does not show a metabolic advantage (80) and we know that (saturated) medium chain triglycerides from coconut oil increase metabolic rate (81) as well as being satiating (82) and thus may have some beneficial effect on weight loss. Dietary saturated fat also works with dietary PUFAs by promoting the uptake of long-chain omega-3 fatty acids from fish oil into the tissues (83).

The war against saturated fat was not founded in scientific evidence and in part 1 of this series I gave some of the history of the drive by commercial interests to demonise saturated fat, which led to a lack of research on the health benefits of saturated fat. Nevertheless, the evidence I have outlined in this post may make you wonder what other benefits of saturated fat remain to be discovered.

In the next and final part of this series I will give you some more reasons to choose full-fat options and I will outline some simple guidelines on how much fat to eat.

I hope this post will have helped to alleviate some of your fear of saturated fat.

Does this information about the benefits of saturated fat surprise you? Let me know your response by leaving a comment below.

SIGN UP TO THE NEWSLETTER TO BE NOTIFIED WHEN EACH NEW POST IS RELEASED

Read The Low-Fat Fallacy: Part 4- Dangers of a Low-Fat Diet, learn more about my work in London and Totnes, or find out about online consultations.

SIGN UP TO THE NEWSLETTER TO BE NOTIFIED WHEN EACH NEW POST IS RELEASED

 

Related posts:

The Low-Fat Fallacy – Saturated Fat Is Good for You – Part 1

The Low-Fat Fallacy – Saturated Fat Is Good for You – Part 2

The Low-Fat Fallacy – Saturated Fat Is Good for You – Part 4

10 Reasons You Need Cholesterol – Part 1

10 Reasons You Need Cholesterol – Part 2

Which Fats and Oils for Optimal Health?

Endotoxin, SIBO and Thyroid – A Vicious Circle