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:
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:
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:
Studies show that long chain omega-3 FA’s (DHA in particular) have a protective effect in the development of Alzheimer’s Disease through
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:
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:
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:
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:
Our view is not conventional wisdom – but we believe that it does represent the emerging consensus view
At Wellness Garage our approach is personalized:
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.
Dr. Brendan Byrne