[Knufen]

I did my Master Degree in Organic Chemistry where we tried to develop a male contraceptive pill. I spend a lot of time studying sperm so here is a short list of thing to avoid regarding sperm quality (not ranked):

1. Eating and drinking from plastics (This includes aluminum cans which are plastic lined) [a]

2. Heating food in ANY type of plastic [a]

3. Caffein intake [b]

4. Sugar intake [c]

5. NOT exercising regularly [d]

6. Alcohol [e]

7. Age [f]

8. Stress [g]

9. Soy products or other natural products containing phytoestrogens [h]

I edited the comment to add point 8 and 9.

Funnily enough these goes for both genders regarding fertility. If you are considering having a child, it takes approximately 7 months for sperm to fully develop so better to change lifestyle sooner rather than later.

a. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222987 b. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5482951/ c. https://pubmed.ncbi.nlm.nih.gov/35606632/ d. https://rep.bioscientifica.com/view/journals/rep/153/2/157.x... e. https://pubmed.ncbi.nlm.nih.gov/28029592/ f. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3253726/ g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6260894/ h. https://pubmed.ncbi.nlm.nih.gov/18650557/

[colordrops]

With all of these it's a matter of quantity. For instance, bullet point 9 about soy makes me question this list. It turns out that phytoestrogens are much less potent than real estrogen, and the only people that were found to have measurable effects from soy was through a study of older men that ate massive amounts of soy every day in Japan. There is real estrogen in cow's milk, which would have a much stronger effect than soy, yet no one speaks about this. Hops in beer also has more phytoestrogens than soy.

[steve_adams_86]

Yes, the data around soy is incredibly underwhelming. A plant like hops does contain more, and more potent, phytoestrogens which many people consume more often than they consume soy. As you mention, milk contains mammalian estrogen which research indicates has notable impact on women’s health in particular (earlier onset of puberty, higher breast and ovarian cancer risk, etc).

Soy seems to fall well within the parameters of “this is fine”, but people readily take any example of it effecting our physiology as evidence of it being harmful. In reality, the evidence of it promoting health overall is extensive and strong.

It could be a component of a plant-based diet for example, which is shown to lead to lower BMI (great for sperm and overall health outcomes). It may reduce sperm concentration to a small degree in large volumes, but the chances are good (statistically speaking) that swapping out something worse in your diet for soy would be a net positive.

[amelius]

Does estrogen in food even enter the blood?

[s1artibartfast]

Anecdotally I know someone that had their ovaries removed as a child and did not know because their high soy diet provided enough estrogen that they had regular menstruation

[ipdashc]

I think I'm missing something. On the Results in study [b], they say

> Semen parameters did not seem affected by caffeine intake, at least caffeine from coffee, tea and cocoa drinks, in most studies. Conversely, other contributions suggested a negative effect of cola-containing beverages and caffeine-containing soft drinks on semen volume, count and concentration.

If tea and coffee don't cause an effect, but cola and soft drinks do, doesn't that imply it's sugar, not caffeine?

[Knufen]

There is an ongoing discussion on the effect of caffein on sperm quality. There are articles which describes a possible route for DNA damage to the sperm from caffein https://www.cureus.com/articles/109365-effect-of-stress-and-.... From personal (lab) experience there is a clear difference to the smell of sperm from a coffee to a non coffee drinker, so it ends up there somehow. Whether it truly has an effect is still being discussed.

[et-al]

Could be correlated to issue 1 with plastic containers. In the US, soda generally comes in aluminum cans or 2L plastic bottles, whereas coffee and tea aren't.

Anyways, I still think sedentary lifestyles and stress play a larger role than plastics, but those are harder to isolate and control for researchers.

[pdpi]

Well, the two sentences following your quote read:

> 2. As regards sperm DNA defects, caffeine intake seemed associated with aneuploidy and DNA breaks, but not with other markers of DNA damage > 3. Finally, male coffee drinking was associated to prolonged time to pregnancy in some, but not all, studies.

And then goes on to conclude:

> The literature suggests that caffeine intake, possibly through sperm DNA damage, may negatively affect male reproductive function.

The whole abstract points at weak/inconclusive results, but we're definitely talking about caffeine here, not sugar.

[ljf]

Or drinks stored in plastic bottles or plastic lined cans? Vs tea/coffee brewed and served in metal/ceramic vessels?

[UglyToad]

Ah yes, that study of 99 (predominantly overweight) men from an infertility clinic that definitely shows soy affects sperm count.

As far as I'm aware the evidence just isn't there with respect to soy and cherry picking the single study that shows some potential link is just helping fuel a dietary myth, would be my view.

[dang]

Can you please make your substantive points without being snarky? This is in the site guidelines: https://news.ycombinator.com/newsguidelines.html.

This is particularly important when correcting misimpressions. If your comment is neutral, the neutral reader can absorb the new information fairly easily. But if you're hostile (as with "ah yes, that, definitely that"), then you're also signaling a pre-existing battle. The neutral reader gets confused by these mixed signals and feels caught in crossfire, which is not a state that's good for learning.

The upside of battle language is that it rallies any readers who are already on your side, but this is not a good move in the HN game. We want curious conversation here, not escalating intensity or repetition of already hardened positions. The value of curious conversation can perhaps be measured by how much the participants, including the silent readers, move in the process.

[Klonoar]

Yeah, I feel like the soy myth has been disproven time and time again but won’t die already.

This and seed oils get hit with the exact same playbook, then disregard significant chunks of the world that have zero issues with them.

[35amxn35]

Perhaps the correlation is the other way around. Men with less testosterone (and therefore a lower sperm count) consume more products with soy, which is common in a vegan diet. Not saying this is the case, just pointing out where this could be coming from.

[lr4444lr]

Comments like this from commenters like this are why I love HN.

Does BPA-free plastic improve anything? What about containers of non-prepared food? I can see not eating directly from any, but I think it's pretty hard in the developed world to rid ourselves of plastics entirely in the storage of foodstuffs.

Also, do we know whether the changes in sperm quality you mention affect congenital childhood maladies? (I realize this is probably beyond your field somewhat.)

[Scaevolus]

BPA is merely one of many endocrine disrupting chemicals found in plastics. Oftentimes BPA is replaced by BPS or BPF to get that coveted "BPA-free!" label, ignoring the fact that the replacements are JUST AS BAD^1. It's a minefield.

Silicone tends to not have endocrine disruptors because it doesn't need plasticizers.

[1]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4492270/

[Knufen]

All plastics are endocrine disruptors [a], though the an easy filter is softer = worse. If anything food related is in contact with plastic there will be plastic in the food. The pH and temperature of the food have a big impact on plastic leaching.

And sperm quality mostly affect fertility. The egg and the body if the woman is incredibly effective at selecting quality sperm and rejecting bad sperm. There are multiple guidance systems for sperm which selects for good quality [b].

a. https://www.niehs.nih.gov/health/topics/agents/endocrine/ind... b. https://en.wikipedia.org/wiki/Sperm_guidance

[lm28469]

> What about containers of non-prepared food?

Wait until you learn about ink contamination from food nets and cardboard boxes.

[throw0101a]

> 1. Eating and drinking from plastics (This includes aluminum cans which are plastic lined) [a]

So drinking containers should generally be ceramic, glass, or stainless steel?

[yamtaddle]

I'd want to know that drinks aren't full of that stuff regardless of the end-user container material, before worrying about it. They're surely exposed to tons of plastics in the manufacturing process, including at times when various components are heated.

Even water supplies in a house will typically have been in contact with plastics—at the treatment plant, in the house for any modern house (they're pretty much all PEX now, since it's stupid-easy and fast to install, which means it's very cheap), in the hot water heater if they're any hot water mixed in (ever start with a hot tap for water you're gonna boil?), if you've got a filter system that's almost certainly full of plastic, and so on.

You'd also have to avoid canned goods of all kinds, not just bottled/canned drinks. Store-bought canned foods have plastic liners, which all but completely solved problems with canned-good spoilage that we used to have, but does mean ~all canned goods are sitting in plastic, not metal, effectively. Glass-canned might be better but are usually more expensive and there's still plastic on the inside of the lids (how much that matters, I do not know—I'd expect very little, but sometimes these things are surprising, for all I know those inside-the-lids bits use exceptionally awful plastic or something).

[mauvehaus]

Or titanium[0]. Neat fact about anodizing titanium: the colors are the result of the thickness of the resulting oxide layer and how it refracts different wavelengths of light[1].

[0] https://www.snowpeak.com/collections/drinkware/products/tita... There are many. This is my favorite.

[1] https://chemistrytalk.org/titanium-anodizing/

[Knufen]

Generally yes. Beware of drinking bottles made from stainless steel. A lot of them are lined with plastic to avoid the metallic taste.

[mc32]

Or leather water bottles as well.

[dj_mc_merlin]

I might as well stop using condoms.

[themagician]

Switch to PS5 + Mountain Dew. 30 minutes before sex, microwave a cookie in tupperware and drink a beer. For added protection, download the critically acclaimed MMORPG Final Fantasy XIV. With an expanded free trial which you can play through the entirety of A Realm Reborn and the award winning Heavensward expansion up to level 60 for free with no restrictions on playtime.

[danuker]

I suppose it's a good idea, if you're trying to conceive :)

[grammers]

This more or less reads like any health instruction (except for the soy products). Would you have a quantity as to how one can change plastic intake by following these recommendations? How strict does one need to be? - I mean basically everything you buy is wrapped in plastic...

[mikodin]

This isn't based on anything except for intuition, take it or leave it :).

Like most things - eliminating the highest points of contact likely would suffice.

Daily habits are the ones that matter.

Are you drinking from a plastic water bottle everyday? Is your water filter plastic? Are you drinking coffee from a keurig or similar? Are you storing food in plastic containers? Are you heating food in plastic containers? Are you using plastic utencils? Are you using plastic lined pans? Are you buying food wrapped in plastic?

Etc etc.

It's a good starting place...then get your sperm tested, it's not prohibitively expensive.

[siglesias]

I cannot recommend highly enough having a set of glass bottles[1] at home. Fill them at the tap (or wherever), refrigerate them, take them to the gym, in the car, serve to guests. Point is to have many, keep a rotation going. Has greatly reduced reliance on plastic.

1) https://amzn.to/3H2YadV

[SoftTalker]

Gyms often ban glass bottles because of the hazard they create when dropped/shattered.

I personally use a hard (i.e. not squeezable) plastic bottle, that I fill with cold/cool water just before use. As long as the water has not been sitting in the bottle for days or in the sun or in a hot car, etc. I don't think there is enough potential chemical leeching to worry about.

[Bud]

Wouldn't metal be far preferable? Especially double-walled metal bottles that can hold liquid at a temperature.

They don't break.

I do have some glass bottles as well for occasional use by guests, but when on the go, the popular metal water bottles seem best.

[zhynn]

You can often buy milk at a coop in a glass bottle which can then be reused. Most of our beverage consumption is out of re-used milk bottles. :)

[irusensei]

> here is a short list of thing to avoid

> 7. Age [f]

wait wat

[nzealand]

Age is also best avoided as it is the number one cause of bodily deterioration, disease and death.

[simonsarris]

"Avoid waiting (delaying) key life things you know you want" is actually great advice that even very smart people seem to fail to consider.

[majkinetor]

Technically, you can easily avoid age :)

[agilob]

Find a younger partner?

[danuker]

Amazing! Thanks for the well-researched info. I did not know aluminum cans were lined. I thought the oxide layer is stable enough.

[bluGill]

The acid in carbonation will eat the oxide layer, so soft drink cans get a thin plastic lining. Alcohol cans often are not lined.

[moffkalast]

I think they just spray them with a thin layer of epoxy, otherwise certain drinks get a metallic taste?

[citizenpaul]

>it takes approximately 7 months for sperm to fully develop

Can you explain this more? I was under the impression it took something like 60days for sperm to generate in the body.

[10g1k]

Agree 100%. I don't eat foods with added processed sugars. I treat sugar like a spice, just throw a pinch in with a few recipes. Sugar is in just about everything in the supermarkets, and is screwing up the entire population.

[torginus]

It is surprising to me that consuming dairy products is not on that list. After all milk is produced by lactating animals (whose lactation is sometimes induced by feeding the animal artificial estrogen). It seems like a fairly direct vector to me.

Why is this so rarely discussed?

[steve_adams_86]

Worth noting is that sperm concentration was the only notable impact of soy consumption, leaving other measured aspects of sperm health unaffected (notably sperm motility, a critical factor in assessing sperm health).

[irrational]

Growing up we never microwaved food in tupperware, but we do it daily now. None of me or my siblings (8 of us) had any sort of mental issues (and it wasn't a matter of not being diagnosed), but all of our children have so many mental issues (depression, anxiety, pulling hair out, ADHD, etc.) that we have asked each other if it could possibly be something in the environment - even though all of us live in different states/cities. Maybe we all reheat food in tuperware and eat/drink from plastics.

[faximile]

This might help me cut down my Coke Zero consumption. Thanks!

Can you suggest any reputable sources for keeping up to date with these best practices, from a consumer PoV?

[grammers]

Thanks for sharing, these studies are extremely interesting!

> Because we can identify existing, relatively inexpensive monomers and additives that do not exhibit EA, even when stressed, we believe that plastics having comparable physical properties but that do not release chemicals having detectable EA could be produced at minimal additional cost.

The only question that I have left: Why aren't we doing this already???

[Aachen]

Just a small note: I noticed that I read your disclaimer that it's not in ranked order, and then went on curious to see what is the #1 cause, and had to remind myself that no it's not ranked. It might help stupid readers like me to use dashes or similar for lists when the order isn't particular, rather than numbering the items!

[concinds]

"Sugar" doesn' seem to include fruits, thankfully. https://pubmed.ncbi.nlm.nih.gov/29266782/

[mikenew]

From what I understand, there is somewhat of a threshold in terms of how much fructose can be digested in your gut vs requiring your liver to get involved. It depends on a lot of factors (body size obviously, your overall calorie intake, some genetic factors, etc), but in general of you're only consuming a few grams of fructose and it's buffered by fiber, you're probably not exceeding that threshold. Fruit fits that bill, unless you're being weird and consuming a whole lot of sugary fruit.

There's a very good interview on the topic here: https://youtu.be/V02z9mqTWzg

[adrian_b]

There is no real difference between eating food to which refined sugar has been added and eating sweet fruits. The sugar is not bound to anything and it is released in the fruit juice when the fruit is chewed, so it is not digested more slowly than when eating a sweetened cake with the same proportion of sugar (but the cakes are frequently made much sweeter than the fresh fruits).

The great danger that has been created by the availability of cheap refined sugar and similar sweeteners, like HFCS, is that it has become extremely easy to create food that has an unnaturally high concentration of sugar or fructose and that it has become extremely easy to eat an excessive amount of sugar per day.

Most cultivated fruits contain around 10% sugar, while a few are sweeter than that, with up to around 16% sugar, like grapes, fresh figs or fresh dates.

When eating only fresh fruits or defrozen fruits, it is unlikely to eat too much sugar, but it is still possible.

It is recommended that the daily intake of sugar should not exceed around 50 g (i.e. around 25 g fructose).

That corresponds to around 300 g of grapes, or around 500 g of apples or pears or blueberries (or most other fruits), so eating amounts less or equal with these every day should be safe.

On the other hand, a single chocolate might contain over 60 g of sugar. Most industrially-made food, including juices or yogurts or breakfast cereals, contains excessive amounts of sugar, so many people eat daily 100 to 200 g of sugar, or even more, without being aware of this.

When eating dried fruits or honey, it is also possible to eat too much sugar without a lot of effort, e.g. around 80 g of most dried fruits is enough to provide the maximum recommended daily intake of sugar.

[majkinetor]

Yeah, right... Totally believable.

[agilob]

Let's not forget how many people were born thanks to alcohol

[moffkalast]

Alcohol now working overtime to somewhat re-address the balance.

[commandlinefan]

> list of thing to avoid > ... > 7. Age

Well, I'm trying my best...

[Conscat]

I'm not sure you have any credibility considering point 9.

[faximile]

They cited a study. If you disagree, please raise the bar, and either challenge the study, or cite something compelling.

[TurkishPoptart]

>1. Eating and drinking from plastics (This includes aluminum cans which are plastic lined) [a]

How do we avoid this? So no Costco plastic water bottles, ever.

[thedorkknight]

>short list of thing to avoid

>7. Age

I find this to be the hardest one to avoid!

[Teknoman117]

9. You just can't win can you?

Eat meat, increase risk of heart disease. Eat soy, decrease fertility.

Life is weird to me. Humans have one of the longest lifespans among mammals, yet we seem to start breaking down not all that far into it. We don't tend to consider 35 "old", as we regularly live 80+ years, and even if you consider the "generally well functioning" span of your life to be your years up to 60 or so, 35 is barely past half way.

Oh well.

[jahewson]

The heart disease thing is probably bogus https://bigthink.com/health/red-meat-cancer-not-health-risk/

[brushfoot]

The soy study is far from conclusive - it showed an inverse association between soy intake and sperm concentration, but mainly in "overweight and obese men," and "total sperm count, ejaculate volume, sperm motility, [and] sperm morphology" remained the same. NEJM Journal Watch stated the findings were inconclusive and recommended against suggesting dietary changes [0].

Either way, soy vs. meat is not the dichotomy it's sometimes presented as in political narratives. You can eliminate both and still have a huge number of healthy world foods to choose from. The Mediterranean I had recently was delicious and soy and meat free.

[0]: https://www.jwatch.org/jw200808070000002/2008/08/07/do-soy-f...

[lm28469]

Half of the west eat and live as if they were attempting a slow suicide. Take care of your body and you'll be healthy well into your 60s, unless you're afflicted by outlier events but you can't do anything about these, maximise what you can, fate will do the rest

[moffkalast]

Life is a known cause of death.

[tdaltonc]

Those all have measurable effects.

But at a population level, which of those are actually driving meaningful fertility decline?

[FollowingTheDao]

EMFs????

https://www.sciencedirect.com/science/article/pii/S230505001...

https://www.sciencedirect.com/science/article/pii/S016041202...

[ceedan]

ibuprofen and acetaminophen also affect quality, which are daily medicines for some people with chronic pain.

[DoingIsLearning]

> acetaminophen

That's paracetamol for the rest of the world in case you were confused like I was.

[SoftTalker]

Neither of these are safe for long-term daily use.

[aidenn0]

> Funnily enough these goes for both genders

So eating and drinking from plastics lowers sperm quality in women too?

[Knufen]

No, but it does affect fertility, as well as various cancers. Breast cancer: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7286136/, cervical cancer: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4801991/ and fertility: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5479690/

[sc90]

In an episode of Succession, Logan was drinking a smoothie that contained Maca Root, Almonds, and Walnuts apparently to boost his Sperm count/chances of having a kid according to Willa. Your list is more of "Dont's". Are there "Dos", based on diet or certain foods that increase the count significantly?

[sizzle]

7 months?? I thought I read it was 120 days, anyone have a reputable source?

[spacedcowboy]

Avoiding age doesn't seem like a great plan for sperm viability ... :)

[addingadimensio]

Careful — saying that plastic is turning the frogs gay is a dangerous right wing conspiracy theory

[Knufen]

Though it is a funny Alex Jones quote there might actually be some meat to it.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC122794/

[kccoder]

Is lower sperm count correlated with a change in sexual orientation?

[asguy]

The Alex Jones motto: Even a stopped clock is right twice a day.

[creaturemachine]

I thought that was the goblins' doing.

[tdehnel]

Cool so my whole life

[rafaelero]

What a list like this misses is some sense of proportionality. We don't need to stress over everything that causes fluctuations on sperm count. The science is not there yet, but personally I am going to bet >50% of the reason for decreased sperms count is because of high protein diets (which correlate to lower testosterone) and high BMI.