Taurine & Metabolic Health 🐂
This Week’s Research Highlight
Background
Imagine a condition that quietly ramps up your risk of most of the top killers of our time, including heart disease, stroke, and type 2 diabetes.
That condition is metabolic syndrome.
Now, metabolic syndrome is actually not a disease per se. Rather, it is a constellation of risk factors that often occur together.
The components of metabolic syndrome include:
- High waist circumference (abdominal obesity)
- High blood pressure
- High fasting blood glucose
- High blood triglycerides
- Low HDL-C
If a patient has at least three of these, they meet the criteria of metabolic syndrome.
You're probably thinking, as you glance at this list, that an awful lot of people nowadays would qualify as having this condition, and unfortunately you would be right. Based on nationally representative data, the current estimated prevalence of metabolic syndrome among American adults has risen to more than 40%. Yikes.
Furthermore, most of us are struggling with at least one of the metabolic syndrome hallmarks. An analysis from the University of North Carolina found that only 12.2% of American adults could be said to have optimal metabolic health, based on the risk factors that make up the criteria of metabolic syndrome.
So how can we turn this around?
First, we must understand the cause.
Metabolic syndrome was first identified back in the 1950s, when physicians noticed that people who accumulated substantial body fat in their upper body were more prone to diabetes, atherosclerosis, gout, and other cardiometabolic abnormalities. But it wasn't until decades later that we recognized that insulin resistance is the underlying factor that connects all of these symptoms together. For example, high blood pressure is very often accompanied by insulin resistance, perhaps due to the impact of elevated insulin on sodium absorption by the kidneys.
To that end, researchers have eagerly sought dietary components that could ameliorate insulin resistance, and in the process improve these risk factors.
One that has emerged is taurine.
Taurine is a sulfur-containing amino acid, which we’ve talked about in this newsletter before. It first got on the radar, with respect to health, after a global epidemiological study coordinated by the WHO found that individuals who had more taurine in their diet (measured via urinary biomarkers) were much less likely to die due to ischemic heart disease.
Since then, taurine has also shown promise in combating insulin resistance and improving glycemic control through a large assortment of animal models, as well as in human trials. For example, in a study of patients with type 2 diabetes, supplementation with taurine for eight weeks elicited substantial reductions in fasting blood sugar (−10.97 mg/dL), hbA1c (−0.21%), insulin (−0.55 mIU/mL), and insulin resistance.
Recently, a team of researchers in Taiwan decided to examine the literature and figure out whether – and to what extent – taurine could be beneficial for metabolic syndrome.
Study
Taiwanese researchers conducted a systematic review of randomized controlled trials examining the impact of taurine supplementation on at least one of the established diagnostic criteria for metabolic syndrome. This encompassed blood pressure, fasting blood glucose, triglycerides, and HDL (apparently there wasn't enough research that looked at waist circumference). In the process, they also looked at some other secondary outcomes related to glycemic control and blood lipids.
The final analysis included 25 randomized controlled trials, pooling data from a total of 1024 participants.
These studies were pretty diverse. Studies were conducted all around the world (in 13 different countries), enrolling participants who ranged in age from 8 to 113 years (!).
Taurine dosages ranged from 0.5 g per day up to 6 g per day, and follow-up periods ranged from one week to one year. Most studies were short term though.
Findings
Let's start with the metabolic syndrome criteria.
Their analysis revealed that, compared to control groups, taurine supplementation elicited statistically significant reductions in:
- Systolic blood pressure: mean difference of −3.999 mmHg
- Diastolic blood pressure: −1.509 mmHg
- Fasting blood glucose: −5.882 mg/dL
- Triglycerides: −18.315 mg/dL
Taurine supplementation did not influence levels of HDL.
(This, by the way, is not a big deal, since HDL is not as important of a risk factor as previously thought, at least compared to LDL.)
Which brings me to the other blood lipid findings.
The researchers found that taurine decreased total cholesterol (−8.305 mg/dL) as well as LDL cholesterol (−6.495 mg/dL).
Finally, taurine supplementation had a beneficial impact on other markers of glycemic control, including:
- HbA1c: −0.341%
- HOMA index (measure of insulin resistance): −0.693
- Fasting insulin levels: −1.521 mU/L
Potential Mechanisms
So why precisely does taurine seem to have this wide array of cardiometabolic effects?
Well, the impressive impact on blood pressure seems to be attributable to changes in factors that regulate vascular tone. In one trial, researchers administered taurine to people with prehypertension. Sure enough, their blood pressure dropped, and blood work provided a clue to why this was happening: plasma levels of hydrogen sulfide (H2S) had nearly doubled in the taurine group. Hydrogen sulfide is a chemical compound produced in the lining of blood vessels that helps arteries widen in response to increased blood flow, and in turn leads to lower blood pressure.
Aside from that, fighting insulin resistance can also improve blood pressure, and that brings us back to the unifying factor of metabolic syndrome. How exactly taurine might enhance insulin sensitivity remains uncertain. But preliminary investigation, using animal models, has yielded some plausible explanations, which we can use to speculate a bit.
For instance, taurine has been shown to elevate levels of uncoupling protein 1 (UCP1), which is found in so-called brown fat cells. Higher UCP1 activity increases glucose utilization and thus lowers blood sugar. Interestingly, one of the trials included in this meta-analysis found that taurine supplementation increased levels of irisin after high-intensity training. Irisin is a myokine that is released in response to hard exercise, and is thought to play a role in the cognitive benefits linked to physical activity. But it's also involved with body fat regulation. Specifically, it increases the expression of uncoupling protein 1 (UCP1), thus promoting thermogenesis and the "browning" of white adipose tissue.
Random Trivia & Weird News
🐂 Taurine is so named because it was originally isolated from ox bile.
Nearly 200 years ago, German scientists Friedrich Tiedemann and Leopold Gmelin first discovered the amino acid in ox bile when they were performing research into the digestive system. Bile acids are linked with taurine in the liver to make them more soluble and more efficient at emulsifying fats in the digestive tract. Accordingly, the new amino acid was eventually dubbed taurine, which is derived from the Latin taurus, meaning ox or bull.
Incidentally, this may also be one reason why taurine improves blood lipids, as we saw in the meta-analysis. Taurine-conjugated bile acids can bind to cholesterol in the digestive system and prevent it from being absorbed, plus the process of bile formation itself consumes cholesterol.
Image credit: Cazcarra Image Group
Random Trivia & Weird News
- Venki Ramakrishnan: Can aging be stopped? A biologist explains. Via Nature Podcast.
- Susan Dominus: How bad Is drinking for you, really? Via The New York Times Daily.
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Taurine
It is worth noting that normal healthy folks don’t really need to worry about suffering frank deficiency of taurine. A typical American diet provides around 120-180 mg of taurine daily, and humans can synthesize small amounts, so you can get by even if your diet contains zero taurine. It is not an essential nutrient, in other words.
However, the benefits of taurine for fighting off the components of metabolic syndrome are usually realized with much higher doses than what you would naturally find in the diet, which is why supplementation is needed. The studies analyzed above used a wide array of doses, ranging from 1.5 g up to 6 grams. Three grams has been shown to be safe for long term use, so a smart dosing regimen for metabolic health might be one gram three times per day — or one capsule in the morning, one in the afternoon, then one at night.
humanOS Catalog Feature of the Week
Heart Health — from The Mediterranean Diet
Taurine may be a secret key to the robust health of people following traditional Mediterranean diets. When researchers examined urinary taurine levels and cardiovascular mortality in people around the world, they found that the populations with the highest taurine levels were in Japan and around the Mediterranean region.
However, it is certainly not the only factor at play.
In this lesson, we dig into some of the diet trials that began to reveal how and why the traditional Mediterranean diet is associated with better heart health. And if you go a little further into the course, you can also get some insight into specific dietary components.
Wishing you the best,
