Tuesday, November 26, 2019

Retrospective #283: TC/HDL, TG/HDL and Triglycerides

Retrospective #281 dealt with HDL cholesterol (HDL-C) and triglycerides (TG). Retrospective #282 took a look at Total Cholesterol (TC), LDL cholesterol (LDL-C) and statin therapy. Now, I will tie them all together and discuss ratios and some recent thinking about using the triglyceride to HDL ratio, and triglycerides alone, to predict CVD risk.
The “lipid” (cholesterol + triglycerides) panel on a typical lab report includes a Total Cholesterol to HDL (TC/HDL) ratio. The standard reference range is <5.0. So, if your TC is 200mg/dL, the limit under which your doctor wants your TC to be, and your HDL is 40mg/dL, the level above which your doctor wants it to be, then your ratio would be 200/40 = 5.0.
Now, since most people’s TC is about 200 or a little higher, and most people who eat a Standard American or “Western” diet will have an HDL hovering around 40, according to this standard most of the population is at risk of Cardio Vascular Disease (CVD). So, what’s a doctor to do? Prescribe a statin, of course! Because a statin, by lowering LDL cholesterol will thus lower Total Cholesterol. Remember the Friedewald formula: TC = HDL + LDL + TG/5.
However, since LDL is not assayed in the typical inexpensive lipid panel lab test, in reality the formula is “transposed” to calculate LDL from the other values which are assayed. So, LDL is calculated as LDL = TC – HDL – TG/5. However, as the math wizards among you will grasp, in the original form, TC = HDL + LDL +TG/5, your TC could be over 200 if any of the components (LDL, HDL or TG/5) was high since TC is the sum of these factors. So, Total Cholesterol is a worthless number. Nevertheless, when you take a statin, Total Cholesterol will get lower, as statins will lower calculated LDL.
As a consequence, if your TC goes lower and your HDL stays the same, your ratio will go lower. For example, a TC of 120 (vs. 200) with an HDL of 40 produces a ratio of 3.0. (120/40 = 3.0). VoilĂ ! Your doctor will tell you that your risk of CVD is now much lower than if your ratio is 5.0, like most people who continue to eat a Western diet but who do not take a statin. If you believe this, I have a bridge to sell you. (Brooklyn Bridge, for those unfamiliar with the old joke.)
But what’s a person to do if taking a statin is not the panacea it’s all trumped up to be? Evidence suggests that “…the strongest predictor of a heart attack” is a different ratio: triglycerides to HDL, or TG/HDL. I wrote about this ratio in Retrospective #27. In #27 I said, “Using this new gold standard, a TG/HDL ≤ 1.0 is considered ideal, a ratio of ≤2.0 is good, a ratio of 4.0 is considered high.” Figure #6 tracks my personal TC/HDL and TG/HDL ratios from 1980 to 2014.
The CONCLUSION in the reference cited in #27 above was: “Elevation in the ratio of TG to HDL-C was the single most powerful predictor of extensive coronary heart disease among all the lipid variables examined.” The full text of the Clinics paper can be seen at Pub Med Central, the U. S. National Library of Medicine, National Institutes of Health. Note that both my TC/HDL and TG/HDL ratios were “borderline bad” until I started eating Very Low Carb in 2002. After, my TG/HDL dropped sharply to “low risk” (≤1.0) in 11/07, and has remained “ideal” ever since.
Now, the latest thinking – this is cutting edge (2014) science folks – is that triglycerides (TGs) alone may be the most reliable risk factor for CVD. So, I plotted another graph charting just my triglycerides.
A cursory glance tells the reader that my TGs averaged about 150 (once again: “borderline”) until I started Atkins Induction (20g of carbs a day) in September 2002. Then, when I started on Bernstein (30g of carbs a day) in September 2006, they fell again. But when I started to supplement with fish oil, and then to eat a can of sardines for lunch almost every day, they plummeted to 21 and have averaged about 50 ever since.
I used to think it was Very Low Carb (Atkins Induction and Bernstein) that caused my triglycerides to be so low. Now that I’ve charted them and researched the milestone dates, I am inclined to think it is the fish oil supplementation and sardines that are the reason. And the reason for my very high HDLs as well. Or maybe just tight compliance with VLC.

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