When I first heard about Rhonda’s paper on ApoE4, Alzheimer’s & Omega-3 Phospholipids – it sounded important, but I had no idea what it was about. For a start, I didn’t know my ApoE4 allele’s from my MSFD2A transporters – so it was an uphill challenge to understand.
In this post I’d like to cover what I’ve learnt from it, and hopefully, make it seem more digestible for others who are also new to the subject.
Table of Contents
Who does this apply to?
This research only applies to ApoE4 carriers, which may make up 20% of the general population.*
The only way to know if you carry ApoE4, is to perform a genetic test (saliva sample based), to sequence your SNPs. The most commonly used for this purpose are 23andMe & Ancestry. At the time of writing it’s noted on the SNPedia ApoE4 page that Ancestry misreports rs429358 (which is relevant to ApoE4), so it may be worth using 23andMe until that is resolved.
*It’s not clear exactly how many people carry the ApoE4 allele. Rhonda’s paper quotes ~25% of the population, citing this paper as the source1Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer’s disease in late onset families – EH Corder et al.. But looking at the paper (and I could be wrong), it doesn’t appear their sample size is enough to draw any conclusions on prevalence of ApoE4.
Why is Rhonda’s paper important?
Having 1 ApoE4 allele confers a 2-3x increase in Alzheimer’s disease risk, and having 2 ApoE4 allele’s confers up to a 15x risk (the most one can have is 2 allele’s).
I don’t need to tell you that this is very undesirable. Alzheimer’s sucks for all involved. It currently makes up ~70% of all dementia cases2Plasma Phosphatidylcholine Docosahexaenoic Acid Content and Risk of Dementia and Alzheimer Disease, The Framingham Heart Study – Ernst J. Schaefer et al (2006).
Rhonda’s paper proposes a way to reduce this risk through the consumption of fish, fish roe (fish eggs) and/or phospholipid DHA supplements (rather than regular DHA supplements).
Which would be fantastic.
For Rhonda, her ApoE4 research is close to home. She reportedly carries at least one ApoE4 allele herself.
How does the solution work?
It would be wrong to pretend we fully understand how Alzheimer’s develops. But we do know that there are 3 hallmarks:
- Extracellular amyloid-beta plaques (extracellular in this context means that the plaques build up outside of the cells, vs intracellular, which would be inside)
- Intracellular neurofibrillary tangles (commonly referred to as tau tangles)
- Reduced glucose uptake in the brain
Something that affects all 3 of these hallmarks is DHA levels in the brain. DHA being the essential omega-3 fatty acid that comprises ~30% of the fat (lipids) in the brain. Higher levels ameliorate the above 3 hallmarks, lower levels increase them.
So the next question becomes… how do we get more DHA into the ApoE4 carrier brain?
Typically, we would eat fish or, consume fish oil supplements, in order to achieve adequate amounts of DHA. There are plant sources of DHA, but the absorption pathway is unfortunately inefficient in humans.
In ApoE4 carriers, it appears that fish oil supplements are not effective, but fish itself is. Why might that be? What does the fish have that the fish oil does not?
Rhonda proposes that this is due to the following:
- Fish contains DHA in phospholipid form, whereas fish oil supplements do not.
- When consuming fish oil supplements, the DHA gets metabolized to nonesterified DHA (free DHA). ApoE4 carriers have impaired brain transport for free DHA.
- When consuming fish, the phospholipid DHA is metabolized to a specific form called lysophosphatidylcholine DHA (that is not a word you want coming up in a spelling test! DHA-lysoPC for short)
- This DHA-lysoPC may bypass the defective transport of free DHA in ApoE4 carriers – allowing them to uptake DHA into the brain.
So, what’s the upshot?
The upshot of all this is that ApoE4 carriers can potentially reduce their Alzheimers risk by consuming more omega-3 phospholipids. In practice, this means eating things like:
In particular cold water fish like salmon, sardines, anchovy, herring and mackerel. Fish contain between 1%–1.5% phospholipids3Marine Omega-3 Phospholipids: Metabolism and Biological Activities – Lena Burri et al. – International Journal of Molecular Sciences (2012).Tinned sardines are a nice go-to option. For things like salmon and mackerel, you’ll ideally want to source wild varieties, as farmed fish often have their fatty acid ratios affected by the unnatural fish feed used.
- Fish Roe
Fish roe (fish eggs) from herring, salmon, pollock, and flying fish contain between 38%–75% of their lipids in the form of phospholipids4Marine Omega-3 Phospholipids: Metabolism and Biological Activities – Lena Burri et al. – International Journal of Molecular Sciences (2012).Wild Salmon Roe is Rhonda’s go-to choice these days for omega-3 phospholipids. For example see this and this Instagram post on the subject. She bulk buys direct from Vital Choice , who offer 2.2lbs in quarters, that can be frozen and taken out when needed.
- Krill Oil
Krill Oil is extracted from the Antarctic crustacean krill, a shrimp-like zooplankton. It is known for a high amount of phospholipid fatty acids, in particular EPA and DHA.People don’t seem to eat whole krill, instead its turned into an oil, for which there are many supplement options. Rhonda previously used NOW Neptune Krill Oil 1000, before switching to a herring roe extract that’s high in phospholipids called Nordic Naturals Omega-3 Phospholipids. I believe she switched to the latter in part due to Nordic Naturals reputation for low oxidation. Oxidation damages the health benefits of the oil.
A great resource for those with ApoE4 are the ApoE4 forums, where there’s lots of informed discussion and ideas around the topic.
- 2Plasma Phosphatidylcholine Docosahexaenoic Acid Content and Risk of Dementia and Alzheimer Disease, The Framingham Heart Study – Ernst J. Schaefer et al (2006)
- 3Marine Omega-3 Phospholipids: Metabolism and Biological Activities – Lena Burri et al. – International Journal of Molecular Sciences (2012)
- 4Marine Omega-3 Phospholipids: Metabolism and Biological Activities – Lena Burri et al. – International Journal of Molecular Sciences (2012)