Wednesday, January 28, 2015

The Nutrition Debate #283: TC/HDL, TG/HDL and Triglycerides

The Nutrition Debate #281 dealt with HDL cholesterol (HDL-C) and triglycerides (TG), and The Nutrition Debate #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 dysfunctional HDL and using triglycerides alone to “predict” CVD risk.
You may have seen the Total Cholesterol to HDL-C ratio (expressed as TC/HDL) on the lipid panel in a typical lab report. The standard reference range (goal or target) is <5.0. There are no units because both components of the ratio have the same units (in U.S. measure, of mg/dL). So, If your TC is 200mg/dL, the limit under which the clinician wants your TC to be, and your HDL is 40mg/dL, the level above which your doctor wants to see your HDL, then your ratio would be 200/40 = 5.0. You’re living on the edge, the doctor will tell you.
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, much of the population is at risk of Cardio Vascular Disease (CVD), according to this standard. So, what’s a doctor to do? Prescribe a statin, of course! Because a statin, by lowering your LDL cholesterol will lower your Total Cholesterol. Remember the Friedewald formula: TC = HDL + LDL + TG/5. (Also, see The Nutrition Debate #25, “Understanding Your Lipid Panel” for an example of a “good” and a “bad” cholesterol panel.
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 inexpensively assayed. So, LDL is now calculated as LDL = TC – HDL – TG/5. However, as the math wizards among you will readily 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, TC is really a pretty worthless number. Nevertheless, when you take a statin, TC will get lower – much lower – as statins will lower your LDL.
And 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 with an HDL of 40 produces a ratio of 3.0. (120/40 = 3.0). VoilĂ ! Your risk of CVD is now much lower than if your ratio is 5.0, like most people eating a Western diet. If you believe this, I have a bridge to sell you. (The Brooklyn Bridge, for those unfamiliar with the old joke.) But what’s a person to do if taking a pill is not the panacea it’s all trumped up to be?

Epidemiological evidence suggests that “…the strongest predictor of a heart attack” is another ratio: the ratio of your serum triglycerides to your HDL cholesterol, expressed as TG/HDL. I wrote about this several years ago in The Nutrition Debate #27 here. 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 the present.
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 here 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. They trended down (except when I went “off diet” in the summers of 2003 and 2006), and dropped sharply to “low risk” when I started Bernstein. Note also that my TG/HDL ratios have been “ideal” (≤1.0) since 11/07, over 7 years and 23 lab reports ago.
Now, the latest thinking – this is cutting edge “science” folks – is that triglycerides alone may be the most reliable risk factor for CVD. The thinking here is that TG, although much more variable than HDL (and TC and LDL), rules out the possibility that high HDL, viewed as generally a very good thing, can also be elevated but “dysfunctional” due to infection, inflammation, diabetes, etc. My editor cited this recent piece in the Public Library of Science (PLOS) to support the new notion. And this piece from PubMed delves into the subject of dysfunctional HDL-C. So, I plotted another graph charting just triglycerides.
 A cursory glance tells the reader that my TGs averaged about 150 (once again: “borderline”) until I started Atkins Induction in September 2002. Then in the summer of 2003 I went “off diet” and my TGs skyrocketed. I returned to “the program” until the summer of 2006 when I started raiding the freezer at bedtime and gained back 12 pounds from the sugar/fat (ice cream). And when I started on Bernstein 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 6-12-12) that caused my triglycerides to be so very low. Now that I’ve charted them and researched the milestone dates, I am convinced it is the fish oil supplementation and the sardines that are the reason. And quite possibly the reason for my high HDLs as well. As I show in Figure #3 in The Nutrition Debate #281 here, there is a very strong inverse correlation between low triglycerides and high HDL cholesterol.
Have you checked your ratios?   Do you know your trig level? 

No comments:

Post a Comment