The ketogenic diet involves eating a lot of fat, so it’s very important that we consume a good variety of fats. It’s also true that we can produce our own fat by converting the carbohydrates we eat. Millions of us (usually due to carbohydrate intolerance) produce it in abundance if we are not careful and end up carrying it around. However, some certain types of fats must be obtained from our diet, and are essential to our survival.
The word essential is used in a dietary context to indicate things that the body absolutely needs, but cannot produce itself in order to survive. The essential fatty acids we need are:
- Omega-3 – These provide anti-inflammatory benefits, helping manage cholesterol, joint care, and blood pressure.
- Omega-6 – Again, blood cholesterol and supporting healthy skin – but too much can have inflammatory effects however.
There are in fact only two essential fatty acids that our body simply can’t produce, and are commonly found in plant and seed oils.
- linoleic acid – (LA) – omega-6 fatty acid
- alpha-linolenic acid – (ALA) – omega-3 fatty acid (you can see the structure of this here)
Remember these well, as they will crop up a lot when discussing essential fatty acids, are are the primary compounds we are talking about when you see omega-3 and omega-6 on nutrition labels and advertising.
Most foods (cooking oils especially) containing polyunsaturates will contain one or both of these in various proportions.
Numerous processes in the body rely on EFAs (Essential Fatty Acids), including:
- Allowing the transport of oxygen in our bloodstream
- Promoting cardiovascular health
- Promoting brain development
- Reducing bad cholesterol
- Anti-inflammatory (except higher doses of omega-6)
- Reducing blood pressure
- Maintaining cell membranes
- Maintaining kidney functions
- Preventing unwanted clotting
Very important fatty acids
While LA and ALA are essential, there are other very important fatty acids we need, such as omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
In fact EPA and DHA (in particular DHA) are primarily responsible for the benefits that omega-3 faty acids provide.
How much Omega-3 and Omega-6 fats should I eat?
We generally consume way too much omega-6 (it’s in just about every cooking oil), and barely enough omega-3.
The only way to create EPA and DHA is through conversion from ALA, although the conversion process is very inefficient. Also, there are studies that show that omega-3 and omega-6 fatty acids compete for the same conversion enzymes – essentially the more omega-6 you consume, the less you are able to convert ALA to EPA and DHA.
For this reason it makes sense to carefully monitor our omega-6 intake, and get EPA and DHA directly from our diet because both are readily available in oily fish (salmon, mackerel, herring), meat and egg yolk.
This direct dietary route to EPA and DHA is not available to vegetarians, and so omega-6 restriction/management is particularly important.
Too much of a good thing?
An realistic optimal ratio of omega-6 : omega-3 in terms of calories is no higher than 3 : 1.
The typical westerner currently consumes in a ratio of 15:1 or more – which is probably why we have such a high incidence of heart disease.
For millions of years our diets have been high in omega-3 sources (seafood, meats), but relatively low in omega-6 fats (derived primarily from seeds and plants). Research suggests that the ratio of omega-3 to omega-6 consumed was around 1:1. However, since the agricultural revolution our intake of omega-6 has increased unabated due to the increasing prevalence of seed and plant oils in our diet. Even the change in animal feeding patterns (think corn fed beef – yuk) has altered the fatty acid composition of farmed meat.
The link between over consumption of omega-6 and a whole range of inflammatory diseases (obesity, diabetes, cancer, IBS etc) has long been argued.
I’ll ask again, how much Omega-3 and Omega-6 fats should I eat?
Okay, okay! It’s very difficult to give exact numbers because one mackerel doesn’t contain the exact same amount of fat as the next haddock! The only way to be sure you are getting the balance between omega-3 and omega-6 intake right is to go for expensive blood tests.
It is widely accepted that the ratio of omega-3 to omega-6 is important, but it is also important to look at the absolute amounts of each we consume. You can find out more about which fats contain more or less omega-3 and omega-6 here.
There are various suggestions from various authors, but a reasonable suggestion would seem to be to consume only around 3% of your daily calories from omega-6 fats and in turn ensure you are consuming around three 120g portions of oily fish a week.
You can get an idea of the amount of EFAs in common foods in the table opposite.