I just came across this interesting study and I'm not sure what to make of it.
In a randomized controlled trial, participants were fed either white bread or whole grain sourdough style wheat bread for 6-weeks (the whole wheat contained some other ingredients, inclduing flax and soy).
They also measured ApoE genotype (there's been some discussion of ApoE on PH before, but I don't know much about it myself).
At first no major differences were noted but "When genetic variation was considered, albeit limited by retrospective assessment, it was found that in those with the APOE E3/E3 genotype, whole grain wheat sourdough bread unfavourably increased LDL-cholesterol in NGI participants".
So people with a copy of either ApoE2 or ApoE4 didn't experience this. I guess that leaves me with 2 questions:
Whole grain contain more irritants, LDL is our body's equivalent of tiny bandaids. More damage would equal the need for more healing. I'm not sure why it wouldn't have an effect on ApoE 4 the same as ApoE 3, because neither of those populations were put through the selective pressure to consume as much grain as ApoE 2 which is the "natural grain eater".
In case anyone is as curious I am, I have a incredibly speculative hypothesis about this study and decided it would be better to make it an answer.
Maybe you've seen Denise Minger's blog post "The China Study, Wheat, and Heart Disease; Oh My!" where she discusses the strong correlation she found between wheat and heart disease. Yes, ultimately just correlation. She also brings up a few studies, namely this one in which wheat germ raised LDL a little bit and flax seed lowered LDL. This study was almost the same (but longer and only in women) and found the same; wheat germ raised LDL.
So perhaps something in wheat germ raises LDL cholesterol. And perhaps (based on the original study in this question) this something interacts with ApoE (which is a part of LDL particles, so this unsurprising).
I recently learned about a physiological difference between the various ApoE phenotypes; varying numbers of sialic acid. Why is sialic acid important? Wheat Germ Agglutinin, the infamous lectin in wheat, binds to sialic acid.
I have no idea what effect the binding of WGA to the sialic acid in ApoE would have on anything as this area has very little study. But this is my point: I believe the study in question is very weakly suggestive of an LDL raising property of Wheat Germ Agglutenin. How or if this is related (indirectly or otherwise) to heart disease risk I could even less guess.
If anyone has any thoughts on this I'd love to hear it.
Hack my hypothesis on wheat and LDL 3 Answers