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This month's highlights

Dr Jim McMorran BM BCh PhD DCH DRCOG MRCGP FRCGP

In this month’s update, I ask whether the paradigm of LDL-cholesterol being “bad” cholesterol is refuted by the advent of the “lean mass hyper-responder” (LMHR) dyslipidaemic phenotype?

What is an LMHR individual? Well, the term has been coined by Feldman et al to describe a group of lean and athletic individuals who, when on a low-carbohydrate diet (a “ketogenic” diet), produce a metabolic response where they have very high LDL-cholesterol (greater than 5 mmol/L or 193 mg/dL) and high HDL-cholesterol (or “good” cholesterol).

An interesting experiment showed that increasing carbs with an “Oreo diet” in an LMHR individual who was previously on a low-carbohydrate diet – literally eating additional carbs in the form of 12 Oreos per day – led to a greater reduction in LDL-cholesterol than using a statin (rosuvastatin 20 mg/day). This experiment suggested that the increase in LDL-cholesterol to greater than 5 mmol/L in an LMHR individual was purely the metabolic response to a low- carbohydrate diet.

The LMHR advocates argue that, in the context of an LMHR individual, there is no increased risk of cardiovascular disease associated with LDL-cholesterol as these individuals are “metabolically fit". There are data to be published imminently on the use of coronary calcification scans – a way of looking at heart blood vessels for early asymptomatic heart disease – that may provide more evidence that raised LDL-cholesterol in an LMHR individual is not associated with increased cardiovascular risk.

If the LMHR data hold true, then the paradigm may become: “LDL-cholesterol is bad cholesterol some of the time... High LDL-cholesterol can precipitate atheroma but only if other factors align.”

Anyway, this an interesting bit of developing knowledge. For more details concerning the “lean mass hyper-responder”, see here.

Other highlights in this month’s email include an evidence update regarding the role of exercise in the management of depression, an explanation of “breakthrough measles” and a key facts summary of nitazenes.

  • Nitazenes: This is a group of compounds developed in the 1950s as opioid analgesics but that was never approved. A characteristic of nitazenes is their high potency; etonitazene, for instance, is 500 times as potent as heroin (by way of comparison, fentanyl is 50 times as potent as heroin). In the UK, nitazenes have been detected in substances sold as other opioids, benzodiazepines and cannabis products.
  • Lean mass hyper-responder: This dyslipidaemic phenotype is summarised.
  • Glycaemic index and glycaemic load: The glycaemic index of a food is the capacity of a portion of that food containing 50 g of available carbohydrates to raise blood glucose compared with 50 g of glucose in normal glucose-tolerant individuals. The glycaemic load of a food is essentially a product of the glycaemic index and the available carbohydrate. This update provides evidence as to how low-glycaemic-index diets can help with the management of type 2 diabetes and how the consumption of high-glycaemic-index foods increases type 2 diabetes risk.
  • Smoking cessation and e-cigarettes: Updated evidence is presented on the use of e-cigarettes in smoking cessation.
  • Breakthrough measles: This condition is given the “key facts” treatment. Is “breakthrough measles” more infectious than “primary measles”?
  • Exercise in the management of depression: This section has been updated.

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