Health & Fitness Digest - 15 December

In today's digest:

  • How blood donation affects fitness levels
  • Are babies born via C-section at higher risk of obesity?
  • Does soy impact testosterone in men?

How blood donation affects fitness levels

I like to donate blood from time to time, both for the sake of “donating” as well as for health benefits (which I’ll talk about in another post in the future).

However, one of the things which concerned me when I was racing triathlons on a regular basis was the potential impact of donating blood on training / racing performance, because there is a significant one.

As this meta-study shows, a blood donation of 400-500ml (standard in most cases) does have a significant and prolonged impact on a number of fitness-related parameters, including hemoglobin levels (oxygen-carrying red blood cells), as well as VO2max and maximal exercise capacity. The results persisted up to 48 hours, and in some cases, for a few weeks.

In an ideal world, you do not give blood within 2-3 weeks of a major fitness event, and you plan your training to factor in the reduced performance post-blood donation.

If you are looking to aid in post-donation recovery, there are a few things you can do, such as: B-complex vitamin, magnesium, tomatoes (lycopene), iron-rich meats (red meat), eggs, etc. And don’t forget to hydrate to replenish blood volume levels.

Are babies born via C-section at higher risk of obesity?

This seems to be the case according to the latest research, which is not that surprising given the various research I’ve read over the past 2-3 years.

Open any medical journal today and you’ll likely to find reference to the “microbiome”. This refers to the population of bacteria living in our digestive system and skin, and they FAR outnumber our OWN cells.

In a completely healthy person, we enjoy a symbiotic relationship with this microbiome: we feed them the right foods, they help us build a strong immune system and a more efficient metabolism.

However a disruption in the microbiome can lead to opposite results: weak immune system and increased risk of diabetes and obesity.

While the science behind how our diet and lifestyle affects our microbiome is clear (e.g. sugary foods disrupt the microbiome), recent evidence has emerged regarding 2 important factors impacting the microbiome for babies:

While in the womb, babies do not have much of a microbiome. They obtain their microbiome through 2 mechanisms:

  • From contact with the mother’s body during the birth process.
  • From the mother’s breast-milk.

This is how nature “equips” living mammals with their microbiome for the rest of their life: natural birth process + breast milk.

Babies born via C-section do NOT get exposed to the mother’s microbiome, and the baby ends up absorbing whatever it comes in contact with, potentially creating long-term immune system and obesity issues. Same thing goes for breast-milk.

Of course, in many cases, C-sections are warranted because of birth complications, and scientists are now looking at ways to “inoculate” the baby with the mother’s microbiome artificially.

Does soy impact testosterone in men?

It’s no secret that I’m not a fan of soy. I’m not a fan of the taste, but more importantly: the research I’ve read over the years has convinced me that the health benefits are over-hyped and potential health downsides are significant.

One such potential downside is the impact of soy on testosterone in men. This is a serious issue since we seem to be facing an epidemic of low testosterone in men driven by stress, environmental toxins, deodorants, shampoos, high sugar diets, etc.

This study published in the Journal of American College of Nutrition puts yet another nail in the soy coffin: just 14-days of soy protein powder taken by young trained men led to a significant decrease in testosterone levels. This is even more concerning for older men (such as myself, close to 40) when testosterone levels drop precipitously.

One thing to be also aware of: testosterone deficiency is a serious health hazard linked to a wide variety of diseases, including heart / cardiovascular disease, diabetes, metabolic disorders, and more.


For any questions / comments, please post below.