Guide to Fats

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​We are back - after a few weeks in South America: Galapagos and Machu Picchu!

​Our last post was about saturated fats and the back and forth controversy about the negative health effects (or not) from consuming saturated fat.

Many of you found this to be a bit deep in the weeds of science, so I thought this week's post would back up a little bit and provide an overview of fats with some take-home practical advice (and of course some science).

Let's start with  definitions:

• Fats - also known as triglycerides are esters of 3 fatty acid chains with glycerol serving as the backbone.  Fat is one of the three main macronutrients, along with carbohydrates and proteins.   Fats are broken down in the body to release glycerol (which is converted to glucose in the liver) and fatty acids. Each gram of fat releases 9 calories of energy.  Fats are categorized according to the number and bonding of the carbon atoms:
  • Saturated fats have no double bonds between the carbons  
  • Unsaturated fats have one or more double bonded carbons in the chain.
    • Polyunsaturated fats (PUFA) have multiple double bonds.  
    • Monounsaturated fats (MUFA) have a single double bond.  These are considered heart healthy.
• Fatty acid chains may also differ by length, often categorized as short to very long:
  • Short-chain fatty acids (SCFA) are those with fewer than 6 carbons - they are produced by the good bacteria in your gut and provide the main source of nutrition for the cells in your colon.  Their absorption into the blood also plays an important role in health - where they may reduce the risk for inflammatory diseases - including Type II Diabetes, heart disease, and obesity.  More on this in the future.... How Short-Chain Fatty Acids Affect Health and Weight  
  • Medium-chain fatty acids (MCFA) are those with 6–12 carbons, which can form medium-chain triglycerides (MCT's).  MCT oil has some unique properties that can be leveraged to enhance fat metabolism and as part of a ketogenic strategy - again more on this in the future...
  • Long-chain fatty acids (LCFA) are those with 13 - 21 carbons
  • Very long chain fatty acids (VLCFA) areare those with 22 or more carbons.
• Most fats (triglycerides) found in food, whether vegetable or animal, are made up of medium to long-chain fatty acids, usually of equal or nearly equal length.

For humans there are two essential fatty acids (fatty acids that we need for our health and cannot synthesize ourselves therefore we must consume in our diet), both are PUFA:

• alpha linolenic acid (ALA) - an omega 3 fatty acid.  (the 3 signifies that the double bond is three carbons in from the omega (or non-glycerol end).  From ALA, we are able to synthesize the other important omega 3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic (DHA).  The efficiency of this conversion is low (especially in the presence of high Omega 6’s) and is lower in men as compared to woman.  There is also significant genetic variation with the FADS enzyme that converts ALA to DHA and EPA.  As a result, it is generally recommended that EPA and DHA are obtained from diet (fish) and/or supplementation.
• linoleic acid (LA) - an omega 6 fatty acid.  (again the 6 means the double bond is six carbons in from the omega end).

(warning: we are diving back into the science)

Both Omega 3 and Omega 6 FA’s are important  structural components of cell membranes, incorporated into phospholipids where they are affect membrane function.  Increased dietary levels of Omega 3’s result increased membrane content of Omega 3’s with resulting improvement in membrane fluidity, flexibility, permeability and the activity of membrane-bound enzymes.  DHA is selectively incorporated into retinal and neuronal membranes highlighting the important role it plays in vision and nervous system function.

It is worth noting that these membrane-bound HUFA are damaged by free radicals released by mitochondria under oxidative stress - this mechanism may be a contributing factor in the development of insulin resistance, the process whereby the membrane bound insulin receptor loses its ability to respond to insulin efficiently.

Under the influence of hormones and cytokines, membrane bound Omega 3 and Omega 6 FA’s are metabolized into multiple classes of PUFA-dervied bioactive lipids involved in inflammation and immune function. 

Only ALA and LA are essential - all other Omega 6 and Omega 3 HUFA's can be derived from these precursors.

LA is common to many vegetable oils (corn, soybean, sunflower)
ALA can be derived from plants sources - flax, chia seeds, green leafy vegetables, soybean oil, canola, and importantly from fish.

In general compounds derived from the Omega 6 pathway are inflammatory and  those from the Omega 3 pathway are neutral, anti-inflammatory or even promote resolution of inflammation.

Evidence supports that increasing intakes of long chain Omega-3’s (EPA and DHA) decrease the risk of cardiac disease by:

1. preventing arrhythmias
2. decreasing the risk of thrombosis
3. decreasing serum triglycerides
4. slowing the growth of atherosclerotic plaques
5. improving vascular endothelial function
6. lowering blood pressure
7. decreasing inflammation

Studies show that long chain omega-3 FA’s (DHA in particular) have a protective effect in the development of Alzheimer’s Disease through

1. mitigation of inflammation 
2. improved cerebral blood flow
3. reduced amyloid aggregation

Omega-3 and Omega-6 FA’s also modulate the expression of genes associated with fatty acid metabolism and inflammation by interacting with transcription factors.  

Omega 3’s suppress NFkB a transcription factor associated with inflammation; as well as suppressing SREBP-1 which decreases fatty acid synthesis.  In this way Omega-3 PUFA functions as feedback inhibitors of fatty acid synthesis.

There are two challenges to Omega 3 metabolism from ALA to EPA and DHA:

1. the enzymes to convert LA and ALA into their respective metabolites compete.  In the presence of high levels of LA,  ALA conversion to anti-inflammatory EPA and DHA will be very limited to non-existent.  Historically humans consumed roughly equal amounts of Omega 3's to Omega 6.  Now the ratio in Western diets is 25:1.  At these levels, we cannot metabolized ALA to protective EPA or DHA.  
2. the second problem is that overall efficiency of the conversion is low (lower in men than women) and there are significant common genetic variants in the FADS enzyme that further worsens the conversion.

So for all effects and purposes, we must consume EPA and DHA from our diet - if we want to ensure we want to get the Omega 3 health benefits.

EPA and DHA are most commonly consumed from cold water fish or fish oil.  The actual compounds are synthesized by algae and are preserved in the food chain in fish oil, so it is possible to get algae derived EPA and DHA (important for vegans, and probably the most ecologically sustainable).

The key to getting the health benefits of the essential fatty acids is to get a proper balance of Omega 6 to Omega 3.

From an evolutionary perspective, the ratio of Omega 6 to Omega 3 in the diet was 1:1.  Since the introduction of cheap, industrial vegetable oils - corn, soybean, safflower etc.  into the Western diet - this ratio has sky-rocketed to 25:1.  At these levels, Omega 6's act as pro-inflammatory agents and likely are a significant contributor to obesity, insulin resistance and heart disease.

These industrial oils are pervasive in packaged foods and restaurant prepared meals and should be avoided.  

The easiest substitution is to use extra virgin olive oil or avocado oil instead.  These oils are predominantly monounsaturated.

At the same time, increasing Omega 3's, either through the consumption of fish or through Omega 3 supplements.

Research suggest that an Omega 6 to Omega 3 ratio of 2:1 may guard against certain cancers, reduce inflammation in rheumatoid arthritis, and potentially decrease the risk of heart disease and Alzheimer's 

The relative amount of EFA requirement is relatively small - about 1% of daily energy requirements from each of these two classes.  1% of 2000 calories = 20 calories - 9 calories per gm of fat = 2.2 g each of Omega 3 and Omega 6.

For more precision you can measure how much Omega 3's you need to consume by measuring one of two metrics:

1. Omega-3 index: is defined as the amount of EPA plus DHA in red blood cell membranes as expressed as the percent of total RBC membrane.  High risk <4%; intermediate risk 4-8% and low risk >8%.  Recommended dose of EPA to increase levels to >5% is 1 g/day, which is equivalent to 3 oz of salmon; however there is significant variation as some people need more to achieve these levels.  Further individuals at higher risk benefit from higher levels of EPA+DHA.  At Wellness Garage we can measure these levels for clients.
2. Blood EPA/AA ratio is also clinically relevant - high ratios have been associated with lower incidence of major coronary artery events - this ratio appears to account for most of the difference between Japenese and Americans in terms of heart disease.

(if you are interested in measuring these - please contact us).

What fats to eat?

Since the requirements for essential fats is small in both a relative and absolute sense, we come back to the question - what fats to eat?

One line of thinking when it comes to dietary fat, it to consume fat in the form that the body likes to store:

Composition of fat stored in adipose tissue:

• 55% = MUFA
• 18% = PUFA
• 27% = SFA

Interestingly a 50:50 mixture of butter and olive oil approximates the composition of triglycerides stored in our bodies.

But isn't Saturated Fat bad for you ?  Probably not - see this blog post.

Current evidence does not support that dietary intake of saturated fat increases risk of CVD.

While increased levels of circulating SFA does correlate with increased risk of CVD and Diabetes - dietary intake of fat does not determine circulating SFA.  In a fat adapted individual (someone who is burning fat for energy), dietary SFA will be quickly consumed as fuel.  The real danger is the combination of high fat and high carbohydrate intake, where both dietary intake and insulin action will increase circulating SFA.  What does get confusing is evidence that replacing saturated fat with PUFA improves CVD risk.


Summary and Recommendations:

• most fat calories should come from MUFA and SFA
  • healthy fats for cooking:
    • High heat
      • Clarified butter or ghee
      • Grapeseed oil
      • Avocado oil
    • Medium heat
      
      • Coconut oil
        
      • Extra-virgin olive oil
    • ​​Cold
      • ​​​Hemp seed oil
      • Pumpkin seed oil
      • Walnut oil
      • Hazelnut oil
      • Flax seed oil
• limit Omega 6 PUFA
• balance Omega 6 and Omega 3
  • generally this means increasing Omega 3's to 2 g/day and decreasing Omega 6 intake
• understand your baseline risk for CHD before making dietary changes and reassess your risk afterwards
  • there is significant individual variation in response to changes in different macronutrient proportions and fat breakdown

For Optimizers:

• measure your Omega 3 Index - target >8%
• measure your EPA/AA ratio - target >0.75

Our view is not conventional wisdom – but we believe that it does represent the emerging consensus view
At Wellness Garage our approach is personalized:

• have a clear-eyed look at all the evidence
• assess our clients fully
• understand their goals
• make a change
• measure the results
• understand what works for that individual

This is the basis of our Precision Health Tune-Up's.

If you think that you benefit from a personalized approach to cardiovascular risk - please reach out to us and book a free consultation, we can help you come up with a plan to address your health needs.