High Triglycerides (Hypertriglyceridemia)

High Triglycerides (Hypertriglyceridemia)

Triglycerides are the transport and storage form of dietary and endogenously synthesised fat, carried in chylomicrons after a meal and in very-low-density lipoproteins between meals. Between 25 and 30 percent of US adults have a fasting concentration at or above 150 mg/dL. The measurement is unusually sensitive to what preceded it: recent carbohydrate intake, alcohol and fasting duration all move it, which is why a single elevated reading carries less weight here than for most lipid markers. Clinical reviews of hypertriglyceridaemia have set out the diagnostic thresholds and the graduated concerns attached to them ^[1].

Consequences differ sharply by severity. Moderate elevation is associated with cardiovascular risk largely through the company it keeps, since it clusters with insulin resistance, central adiposity and low HDL cholesterol. Severe elevation above roughly 500 mg/dL introduces a separate and more immediate concern, acute pancreatitis, and may produce eruptive xanthomas or lipaemia retinalis. Below that threshold the condition is asymptomatic.

Four ingredients are graded against this endpoint, on 63 studies and 24,300 participants, and the grade distribution is the cleanest ladder in the collection: one entry at each of A, B, C and D.

Omega-3 fatty acids hold the Grade A rating on 50 studies and 20,000 participants, and the mechanism is well characterised. EPA and DHA reduce hepatic production of very-low-density lipoprotein and increase the clearance of triglyceride-rich particles, an effect that is dose-dependent and that grows more pronounced the higher the starting concentration. Triglyceride lowering is the one lipid endpoint on which the marine omega-3 literature is largely concordant, in contrast to the mixed record these same fatty acids hold against rhythm and event endpoints elsewhere in this collection.

Niacin holds Grade B on 8 studies and 4,000 participants. It reduces adipose lipolysis and hepatic triglyceride synthesis, and its lipid effects were established long before its outcome trials were completed. Its practical difficulty is tolerability, since the prostaglandin-mediated flushing that accompanies immediate-release forms is dose-limiting for many people; the postprandial metabolic effects of the immediate-release form have been studied directly in men with metabolic syndrome ^[2].

Omega-7, or palmitoleic acid, holds Grade C on 2 studies and 100 participants, and chitosan Grade D on 3 studies and 200 participants. Both rest on evidence bases too small to distinguish a real effect from chance.

All four entries are recorded with a positive direction. Even so, triglycerides respond more readily than most lipid markers to non-supplement measures: refined carbohydrate intake, alcohol, body weight and insulin resistance all appear among the listed risk factors, and alcohol in particular can dominate the reading in an individual whose other risk factors look unremarkable.