What is the best source of fat on a ketogenic diet?
The ketosphere is pretty segregated, almost in a religious manner, on this issue. Some argue that we evolved to eat animal proteins and fats. This includes a higher proportion of saturated fats, which are stable and resistant to oxidation. Others argue Mediterranean-keto is superior, given its high proportion of healthy monounsaturated fats (olive oil), Omega-3 fats (fish), and probiotic plant material, as well as the association between Mediterranean diets, longevity, and low rates of Alzheimer’s disease (1).
We come to the discussion with our own biases, often informed by our personal, and very legitimate, health journeys. But this piece isn’t about sticking to our guns; it’s about thinking critically to add nuance to the discussion and, hopefully in the process, help you optimize your personal “fatome.”
But, wait, what’s a “fatome?” You’ve heard of the genomes and microbiomes. These are the unique sets of genes and microbes that fingerprint each of us and interact within our bodies to influence our health. Why shouldn’t we have a “fatome” -- the unique balance of fats we each consume in our diets that influences our health?
The key word in the above paragraph is “interacts”. Each “ome” interacts in its own network and with others. The genome, microbiome, and fatome all talk with each other. And, as with any team, the qualities of one player should complement those of the others.
In short, there is no one best “fatome”. We can’t tell you what your is, but we can nudge you down the road of self-study by providing the following background information to hopefully help you decide what fatty factors are most important to you.
1. Long-Chain Saturated Fatty Acid Profile
Not all long-chain saturated fatty acids are equal. Long-chain saturated fatty acids differ in the length of their tails, from 12 carbons to 22 carbons.
The four long chain fatty acids to focus on are 14, 16, and 18-carbon, myristic acid, palmitic acid, and stearic acid. In general, myristic acid and palmitic acid can decrease the expression of LDL receptors on your liver (2). This is not bad because it can increase LDL, it’s (potentially) bad because of how it can increase LDL. By decreasing LDL uptake at the liver, LDL in the blood has more time to get oxidized, condense, and become atherogenic. Steric acid does not decrease LDL receptor expression on the liver (2).
Therefore, saturated fat sources that have a higher “stearic acid-to-palmitic acid+myristic acid)” ratio may, in some people, be preferable. If you take a look at the table, this would imply cacao (chocolate) saturated fat may be better than fat from dairy fat. #HighFatFoodforThought
Medium-chain triglycerides (MCTs) go straight to the liver, rather than into systemic circulation. They can also drift into our cells’ mitochondria, without the need for transportation assistance. In short, this means that they get used as more immediate fuel (3) and get turned into ketones.
Coconut oil is rich in MCTs, particularly the 12-carbon, lauric acid. (As an aside, there’s some controversy over whether lauric acid is a long-chain or medium-chain fatty acid. Based on how it’s biologically processed, however, it appears to be medium-chain (4)).
Monounsaturated fatty acids (MUFAs), and their primary sources (olive oil, avocados, and macadamia nuts), many consider to be superfoods. Real extra virgin olive oil (5) is perhaps the best fat source of antioxidant, anti-inflammatory polyphenols. Avocados don’t have quite as many polyphenols, but avocados themselves are packed with healthy fibers and avocado oil has a great smoke point for cooking (more below). However, olive oil and avocado oil have a slight potential drawback: they are each 10-14% Omega-6. These proinflammatory essential fatty acids are fine (and unavoidable) to consume in moderation, but if you are like me and can consume over 1.5 Liters of olive oil per week, those Omega-6 can add up, potentially contributing to higher oxidized LDL levels.
So, if you’re Mediterranean-Keto, what do you do? Here are two suggestions: (i) Add in more macadamia nut and macadamia nut oil, which are rich in MUFAs, but much lower in Omega-6. (ii) I personally found that including some, but not too much, virgin coconut oil and raw organic coconut butter improved my oxidized LDL levels.
Most of the MUFAs in your diet will be oleic acid. Oleic acid is awesome because it gets converted into a metabolite called oleoylethanolamide (OEA) which activates the fat-burning transcription factor PPAR and stimulates TRPV1 receptors on the vagus nerve to make you feel full. There is, however, another (rarer) MUFA worth mentioning: palmitoleic acid, also known as Omega-7. Palmitoleic acid is richest in macadamia nuts, synergizes with Omega-3s (found in fish), and can help to improve serum lipids (6), decrease inflammation (7), and increase insulin sensitivity (8). Omega-7 palmitoleic acid is also the founding member of the class of hormones called “lipokines” (9)!
Fatty Fish (SMASH: Salmon, Mackerel, Anchovies, Sardines, Herring) are your sources of the Omega-3 fatty acids, EPA and DHA. You need adequate EPA and DHA for optimal health as both decrease inflammation and DHA is a major building block of the brain.
Land sources of Omega-3s, such as flax seeds and walnuts, only contain ALA. ALA can be converted into EPA and DHA, but only at extremely low levels. Therefore, you either need to have some fish in your diet or supplement with EPA and DHA in some form. This doesn’t need to be fish oils, if you are vegetarian. Fish get their EPA and DHA from eating marine algae, so there are also algae-based EPA and DHA supplements available as well. If you do supplement, krill oil is ideal because it contains a high amount of a special form of DHA (lyso-DHA) that’s best able to cross into the brain using a special transport system (10).
5. Smoke Points
You ruin an oil if you overheat it. The most heat-resistant fat sources are avocado oil and ghee. Select your favorite (or alternate between both) depending on your personal preference. Most other oils, including olive oil, can be used for low-temperature cooking (see compare and contrast table). Never overheat fish or flax seed oils as they are among the most heat sensitive.
6. Other Considerations: Probiotic Effects, Dairy Sources, & Whole Foods vs. Oils
I hope we can agree that it’s not just about IIFYM (“if it fits your macros”), nor it is simply about IIFYFAP (“if it fits your fatty acid profile”). Here are some additional factors to consider:
(i) Certain fat sources come with probiotic effects. Lauric acid (4) may help to kill off bad bacteria in your gut, while promoting good bacteria. Similarly, the fibers found in avocados and bacteria found in blue cheeses may each help to improve microbiome health.
(ii) Since I mentioned blue cheese, let’s talk dairy. In general, non-cow dairy sources are best. This is because cow dairy contains what’s known as “A1 casein,” which gets turned into an opioid in your gut that is proinflammatory and can cause constipation. Goat, sheep, and buffalo dairy are generally considered safer.
(iii) Consider this: nature often packages fats in whole foods in a protective manner. For example, the Omega-3s in salmon are healthy but fragile. That’s why wild salmon is pink! Yes. That’s why wild salmon is pink. When wild salmon are on their upstream marathon journey to breed, and exercising their little tails off, they generate a lot of oxidative stress. As a result, their bodies make “astaxanthin,” a potent antioxidant that protects the valuable Omega-3 fats. When you eat wild salmon, you get the Omega-3 and astaxanthin (its bodyguard). When you eat only fish oil, you often don’t. That’s just one of hundreds of examples how cleaver nature can be, which is why you always want to prioritize whole foods.
So, let’s return to the starting question: What is the best source of fat on a ketogenic diet? I hope, by now you understand that the answer is not so simple. Your best “fatome” depends on you genome, microbiome, lifestyle, and nutritional perspective. To help you start to ponder, we will leave you with some questions to help you reflect on what you just read:
Like saturated fat? Is it worth considering that not all saturated fats are created equal? Is it worth considering the stearic acid/(myristic+palmitic) ratio?
Are you Mediterranean-Keto? If so, could you be overconsuming olive oil and avocado oil? Is it worth checking out macadamia nut oil and/or incorporating just a bit more saturated fat (virgin coconut oil or raw organic coconut butter)?
Are you eating fatty fish, at least twice per week? Are you getting enough EPA and DHA?
What oils do you use for cooking?
Are your fat sources mostly from extracted oils, or do they include whole foods?
Are your fats “extra virgin” (olive oil), virgin (coconut oil), and/or “raw” (nuts, coconuts, and dairy)?
And, finally, what self-experiments can you do to begin your quest to find your best fatome?
Take Home Message
The “fatome” is the unique balance of fats we each consume in our diets that influences our health. Our optimal fatomes are unique to us and depend on our genomes, microbiomes, lifestyles, and nutritional perspectives.
No medical advice
The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.