Solid vs. liquid fat—a biophysical perspective

As reviewed previously, dietary fats have differential effects on the body in relation to various mechanisms. This post explores why from a more fundamental perspective.

The body is largely an aqueous environment, compartmentalised by amphipathic lipid barriers/membranes containing specific hydrophobic fatty acids; and similarly, lipids are transported in amphipathic lipoproteins and metabolised by water-soluble enzymes (e.g. lipases). However, dietary fats have diverse structures and physiochemical properties. Foremost, unsaturated fatty acids (UFAs) are liquid at body temperature (37°C), while saturated fatty acids (SFAs) have higher melting points, which increase with chain length, resulting in short–medium chain fatty acids (e.g. C3–11:0) being liquid and longer chains solid; with a parallel relationship to water insolubility (Wiki). Could these basic characteristics underlie some of their differential effects?

Differential effects of fats on gut–host health

Dietary fats are ubiquitous and essential, while their quantity and quality modulate health. Recently, effects on the gut microbiome are being revealed. This post explores their differential effects on the gut–host dialog and underlying mechanisms relevant to many diseases.

Dietary fats appear to differentially affect human physiology; and perhaps most notoriously in the case of cardiovascular disease (CVD), the leading cause of death globally. For instance, in large observational studies, substitution analyses suggest opposing effects of saturated vs. monounsaturated and polyunsaturated fatty acids (i.e. SFAs vs. MUFAs and PUFAs, respectively) on CVD ^1–3; a relationship tested and supported by meta-analyses of randomised controlled trials (RCTs) ⁴, and referenced in many dietary guidelines. Further, in 3–4 week RCTs on healthy adults, adjusting the habitual palmitate/oleate ratio (i.e. the most abundant SFA/MUFA) affects blood/tissue lipids, alongside energy metabolism, immune activity and brain function ^5–11. And even single meals with different fats can have markedly different effects on postprandial cardiometabolic biomarkers ¹².

Chocolate vs. CFS: flavanols and beyond

There have now been several preliminary studies testing the effects of phytochemical-rich plants in ME/CFS, some of which show benefit (discussed later). Of these, I find the 2010 trial with chocolate particularly intriguing ¹.

This was a very small pilot trial (UK, n=10 CFS, Fukuda criteria + severe fatigue; no mood disorders, no drugs) to test the effect of polyphenol-rich chocolate for 8 weeks on symptoms. It had a double-blind, placebo-controlled, crossover design (8–2–8), with several subjective outcomes; and high methodological quality in a recent systematic review ². The active treatment arm had an improvement in fatigue, anxiety, depression and disability (pre–post effect: –35%, –37%, –45% and +31%, respectively); anecdotally, 2 people with short illness duration even returned to work ¹. For reference, this is a greater reduction in fatigue, depression and anxiety than over a year of CBT or GET in the large PACE trial (UK, n=641 CFS, multiple criteria), which used some of the same outcome measures ³.

Is NAD low in CFS?

Nicotinamide adenine dinucleotide (NAD) performs central roles in metabolism as a redox cofactor and enzyme substrate. NAD is synthesised via several pathways; in essence from tryptophan (i.e. de novo pathway) or vitamin B₃ precursors (i.e. Preiss-Handler and salvage pathways), with addition of ribose-phosphate (from PRPP) and AMP (from ATP), and amidation to form NAD ¹. Several enzymes (e.g. sirtuins, PARPs and CD38) catabolise NAD by removing the whole ADP-ribose portion releasing nicotinamide (NAM), which can be recycled to NAD in the salvage pathway, or methylated (via NNMT) and excreted.

NAD metabolism is regulated by circadian rhythms ² and daily activities ³, while levels may decline with ageing ^4,5 and disease ⁶. Several authors have also suggested NAD may be low in ME/CFS, based on suspected pathophysiology ^7–10. Currently, there are scarce studies in this area, but below are some preliminary findings I’ve scraped together.

Redox in CFS: to what do we owe this electron flow?

Oxidative stress has long been implicated in CFS. Here are some data summary tables from a draft paper on redox in CFS written around this time. They generally show how an oxidative redox status may affect many molecules and tissues, and associate with many symptoms.

Are carbs really that bad?

Low carbohydrate (carb) diets are advocated for all kinds of health conditions (incl. ME/CFS), by Atkins/weight-loss/Paleo movements and some alternative MDs. These movements demonise carbs and oversimplify their role in health and disease. So here is a reappraisal of the humble carb.