Oxygen-induced impairment in arterial function is corrected by slow breathing in patients with type 1 diabetes (2017)

Citation

Bernardi L, Gordin D, Bordino M, Rosengård-Bärlund M, Sandelin A, Forsblom C, Groop PH. Oxygen-induced impairment in arterial function is corrected by slow breathing in patients with type 1 diabetes. Sci Rep. 2017 Jul 20;7(1):6001. doi: 10.1038/s41598-017-04947-4. PMID: 28729675; PMCID: PMC5519543.

4 FUNDAMENTALS

 

1. Essential Background Material

 

This study evaluated the difference between slow breathing and oxygen administration on autonomic and arterial function in type-1 diabetics.

 

People with diabetes suffer from higher rates of cardiovascular disease and nervous system issues.  Many of the problems are thought to be permanent damage.  However, the author and colleagues (they have several papers we’ll eventually get to) have found that some of these issues are partially reversible in diabetes.

 

For example, they found that the parasympathetic nervous system could be stimulated using either slow breathing or oxygen administration.  This led to a transient improvement in autonomic function in people with diabetes, and a temporary reversal of complications.

 

Although slow breathing and oxygen administration both help, it’s unclear how they work.  For instance, as mentioned, both lead to improvements in autonomic function.  However, oxygen administration generally increased blood pressure, whereas slow breathing naturally lowered it.  This suggests they’re working through different mechanisms that could either be complementary or offsetting.

 

The goal of this paper was to find out.

 

 

2. What Did this Research Do?

 

They recruited 91 type-1 diabetics and 40 age-matched controls, none of which showed evidence of cardiovascular disease.  They had the participants lay down, and measurements were recorded during 5 minutes of spontaneous breathing followed by 2 minutes of slow breathing at 6 breaths/min (5-sec inhale, 5-sec exhale).  Next, they had them repeat this breathing procedure with additional inhaled oxygen (“hyperoxia”).

 

(Note: Inhaled oxygen is potentially valuable for diabetes because many complications are thought to arise from resting tissue hypoxia.  Thus, the idea is that the hypoxia will be alleviated by supplementing with additional oxygen, and complications will be reduced.)

 

So, they ended up with four conditions:

  1. Baseline

  2. Slow Breathing

  3. Oxygen Administration

  4. Slow Breathing + Oxygen Administration

 

Measurements they took:

  • Blood pressure

  • Oxygen saturation

  • Baroreflex sensitivity (BRS), which generally reflects your body’s ability to quickly adjust your blood pressure to match the current circumstances (higher is better)

  • Heart rate variability (HRV)

  • Arterial stiffness

 

 

3. What Were the Major Findings?

 

At baseline, the type-1 diabetics basically had worse measurements of everything compared to the controls: They had lower BRS and HRV, higher blood pressure, lower oxygen saturation, and more arterial stiffness.

 

During oxygen administration, HRV and BRS increased.  However, blood pressure and arterial stiffness also increased (likely due to more oxidative stress).

 

During slow breathing, on the other hand, HRV and BRS increased while diastolic blood pressure and arterial stiffness decreased.

 

During slow breathing + oxygen, the increases in blood pressure and arterial stiffness were counteracted by the slow breathing.

 

 

4. Why Do These Results Matter?

 

There are several significant takeaways from these findings.  First, slow breathing appears to be more protective for the autonomic nervous system and arterial function than oxygen administration in people with diabetes. 

 

Second, slow breathing might also act as an antioxidant.  Recall from above that oxygen administration increased arterial stiffness and blood pressure, likely due to excess oxidative stress.  When oxygen administration was paired with slow breathing, those effects didn't occur.  This suggests that slow breathing acts as a natural antioxidant.

 

How might this be happening?  The authors hypothesize that it’s through vagal nerve stimulation.  Several experiments have shown that vagal stimulation produces antioxidant effects.  However, this paper is the first to show it occurs using slow breathing alone in people with diabetes.  This is especially significant because oxidative stress is a central driver of diabetic complications.

 

Lastly, another important finding was that the parasympathetic nervous system is not destroyed, just suppressed, in people with diabetes.  A simple slow breathing exercise “wakes it up” and acutely reverses components of diabetic autonomic dysfunction.

 

 

1 BIG TAKEAWAY

 

Slow breathing improves autonomic and arterial function while also acting as an antioxidant in people with diabetes.  The last line of their abstract summarizes it perfectly: “Slow breathing could be a simple beneficial intervention in diabetes.”

 

 

1 PRACTICAL APPLICATION

 

If there is any disappointment at all in this paper, it’s this: I emailed the authors and discovered that they performed the breathing protocol through the mouth.  It’s unclear if it was for measurement purposes or not.

 

However, the fact that it was through the mouth might actually be even more powerful.  This suggests the slow breathing pace is most important for autonomic and arterial health, independent of all the other adverse effects of mouth breathing.

 

Thus, we can improve it further by doing it through the nose.  So, the 1 Application is to simply practice slow breathing at around 6 breaths per minute to improve autonomic function and arterial function and reduce oxidative stress.