[ravenstine]

Elevated cortisol (in response to the stress of running or whatever) increases bone resorption and inhibits bone growth. This isn't necessarily an issue for anyone doing lots of cardio, but it's an increase in risk. It also reduces protein synthesis, which is important for both muscle and bone (it isn't just calcium).

[magicalist]

> Elevated cortisol (in response to the stress of running or whatever) increases bone resorption and inhibits bone growth

Cortisol is also released during strength training, though.

Seems like a real issue is low impact cardio, which isn't negative for bone density (as far as I can tell) but does have a theoretical opportunity cost when you could be doing weight-bearing cardio, which does improve bone density.

Agreed with littlestymaar's comment higher up, though, that exercise rates being what they are, the theoretical opportunity cost may be quite theoretical.

[hprotagonist]

> Cortisol is also released during strength training, though.

more than compensated for by the compressive loading signals from lifting heavy.

[ambicapter]

How do compressive loading signals compensate for cortisol production? Seems like one is a nerve signal and the other is a hormone?

[digdugdirk]

The previous post was referring to the overall bone density change. The skeletal loading from strength training is a stronger signal for bone density increase vs the negative impact on bone density from increased cortisol production.

[ben_w]

> Elevated cortisol … increases bone resorption and inhibits bone growth

Would that also be true for caffeine consumption? IIRC it increases cortisol levels, but I don't really know much about what else it does, I've only read the Wikipedia page and gone "Wow, I'm really glad I've already cut back".

[hilbert42]

""Wow, I'm really glad I've already cut back"."

What you said about caffeine worried me somewhat, so I looked it up on Wiki and what I found about it was mostly innocuous and some properties are even beneficial, it's even on WHO's list of essential medicines.

Many vegetables have much more dangerous compounds and toxins: oxalic acid (a rust remover and bleach that can rot your kidneys) in rhubarb and Popeye's spinach and many other green-leaf vegies, solanine in potatoes, and very dangerous cancer-causing aflatoxins in peanut butter, and that's just the beginning, there are many dozens more! Now you know, are you going to starve?

And to boot, caffeine is a nice looking heterocyclic purine-like molecule with a six and a five-member ring both heavily laden with nitrogen, so what's the worry about? What's not to like about it?

[creata]

Being on WHO's list of essential medicines is no indicator of how innocuous a substance is.

[callalex]

It’s really not indicative of much at all. They also spout off about artificial sweeteners despite a complete lack of scientific evidence. It’s a political organization, not a scientific one.

[hilbert42]

I'm sorry you missed the point.

[ben_w]

Re-reading your comment, I think you're the one who missed mine.

I said "cut back" not "cut out".

[ben_w]

https://en.wikipedia.org/wiki/Caffeine#Overdose

"""Consumption of 1–1.5 grams […] per day is associated with a condition known as caffeinism.[141] Caffeinism usually combines caffeine dependency with a wide range of unpleasant symptoms including nervousness, irritability, restlessness, insomnia, headaches, and palpitations after caffeine use."""

"""cases of very high caffeine intake (e.g. > 5 g) may result in caffeine intoxication with symptoms including mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations or psychosis, and rhabdomyolysis."""

[hilbert42]

1-1.5g. Who do you know consumes 10 to 15 cups of coffee per day consistently? I'd suggest very few.

>5g. Now, who do you know consumes more than 50 cups of coffee per day consistently? I'd suggest none.

If you scaled up oxalic acid daily doses in the same ratio as for the caffeine example then in the first instance the person would almost undoubtedly have kidney stones. In the second example the person would be dead. Right, at that dose Popeye's spinach meal would almost certainly have killed him.

At least the 'caffeinated' person, whilst off his head, would likely be still alive.

Even water has a LD50 rating. As millions attest, caffeine is one of the safer less harmful chemicals that plants use to defend themselves with. Almost every other organic molecule that plants use to ward off insects is more toxic.

Here's a few we actually eat: www.mashed.com/1299947/most-dangerous-vegetables/ There are tens of thousands of others that you'd want to keep well away from, Nux vomica, Manchineel, Death caps, Atropa belladonna, etc. By comparison, in the danger stakes, caffeine doesn't even get off the starting block.

[ben_w]

> Who do you know consumes 10 to 15 cups of coffee per day consistently? I'd suggest very few.

Me in 2009, by dose, as a result of constantly increasing my consumption and ending up at multiple tablespoons (not teaspoons) of instant per cup and nothing else but coffee as daily fluid intake.

Hence being glad I'd already cut back by the time I'd read about the impact of too much.

They warned us in school about the dangers of tobacco and alcohol (and all the illegal drugs*), but nobody ever said "there is such a thing as too much caffeine".

There is, and the unlimited free coffee in most workplaces turns out to be a problem for me.

* regarding your point about LD50 water, school also lied about the dangers of Ecstasy. Leah Betts' actual cause of death was water overdose, but she was the literal poster-child for the anti-drugs campaign in my time.

[hilbert42]

"…school also lied about the dangers of Ecstasy. Leah Betts' actual cause of death was water overdose, but she was the literal poster-child for the anti-drugs campaign in my time."

In the wash-up I reckon our views are likely closer to each other than it first seems. I agree completely with you being indignant about being lied to at school.

The whole matter of drug education I reckon is in an unholy mess. However, it's difficult to blame anyone in particular because there are so many factors involved and almost every one of them is complicated by multiple factors. I don't envy anyone involved in setting policy in this area.

There are social and moral issues involved not to mention that both schools and parents often have little factual knowledge about drugs, drug taking, addiction, and likely most have no personal experience of drugs having never taken them, etc. This itself is a major problem.

Thus, often the information they impart to kids comes more from emotion than from actual fact. This often misleading information is also the source of why there are so many views and why it's so difficult to reach a common agreement or consensus.

No doubt both teachers and parents want to keep their kids safe, so they'll tell kids what they think is necessary whether it's correct or not, and they'll do so without due consideration or whether it's prudent to even raise certain matters.

Therefore, it's sort of understandable that teachers, schools and parents lie to kids about such matters. Nevertheless, I strongly believe that lying to kids doesn't pay off as in the long-term it has negative consequences (and I'd reckon that's especially so when it comes to information about drugs).

In my opinion, misinforming kids is a serious matter for whatever reason.

My views and opinions about this go back a long way and owe their origins to an incident that happened when I was very young. (Fortunately it wasn't about drugs because there weren't† any around when I was growing up decades ago, we kids were very lucky in that regard.)

The incident occurred before I'd started school when my mother took me to see a matinee and during the newsreel there was a news clip about cancer and cancer research. Later when I asked her about it, so as not to worry me she told me that cancer was a very rare disease and that I'd never have to worry about it. She also failed to tell me that one of her sisters died of cancer before I was born. So a woman who would have been my aunt died of the disease. Now that's damn close to home I reckon.

It all unraveled a couple of years later when I was about 7 or 8 when I was on holidays at my grandmother's place. Her next-door neighbor was dying of lung cancer and it was my grandmother who told me so—not my mother. That's when I found out my mother had lied to me. I never mentioned to my mother what my grandmother had told me—and I've never forgotten that I was lied to.

We adults almost always underestimate how intelligent kids really are and the moment they get a whiff that they've been hoodwinked is the moment when mistrust first sets in. In my opinion that's really bad, especially so early on because the earlier things are imprinted into kid's minds the harder they are to shift later.

Back to the matter of your sensitivity to caffeine, these issues arose again in another current story that you may be interested in under HN title A chemist explains the chemistry behind decaf coffee (it's not the actual story title): https://news.ycombinator.com/item?id=41067616.

I've made several posts here but the one that's probably the most relevant to you is this: https://news.ycombinator.com/item?id=41076191

__

† Thus, we had no instruction about drugs at school except to be told that if we were caught smoking we'd be in trouble (especially so if anyone was caught doing so at school). And several were caught, they'd sneak off and smoke behind the toilet block down the end of the school yard. BTW, I wasn't one of them (and I don't smoke).

[lupusreal]

1 gram of caffeine is 10 to 20 caffeine pills. Nobody does this without knowing they've got a problem.

[hilbert42]

No doubt! 10 to 20 caffeine pills could be taken at once, my example was cups of coffee per day (rough estimate ≈100mg/cup). Taken over a day it would be better tolerated (but I'd still not consume that amount).