Bodybuilding and fitness forums have gone crazy for a study which looked at the effects of onion juice in rats. We already knew eating vegetables is healthy, but apparently they can also boost testosterone levels – dramatically. The study in question reports that giving rats onion juice increased testosterone levels by more than 300%. But can these results be replicated in humans? Do onions increase testosterone?
- A 2009 study found onion juice to increase serum testosterone levels in rats by more than 300%
- This study caught the attention of online forums – particularly those dedicated to bodybuilding and fitness
- It’s unclear whether the effects also occur in humans
- Onions are rich in healthy phytochemicals which may explain their testosterone-boosting effects
Onions and testosterone: the rat study
“Administration of 0.5 g/rat and 1 g/rat of fresh onion juice daily for 20 consecutive days significantly increased serum total testosterone.“
Rats share all the same organs as humans as well as many other physiological similarities. This makes them a reasonably accurate way to test the effects of drugs and supplements in humans without risking their health.
The authors of a study, Evaluation of androgenic activity of allium cepa on spermatogenesis in the rat, used rats to see whether allium cepa (onion) improved male sperm parameters and fertility.
As discussed in a recent article, men’s sperm counts have fallen by more than 50% in the last 40 years. But antioxidants, such as those found in onions, can protect sperm DNA from free radicals and improve fertility.
To test the effects of onion juice, 30 rats were randomly divided into three groups: control, 0.5g/kg onion juice per day and 1g/kg onion juice per day. After 20 days of treatment, results were observed.
As part of the experiment, researchers measured serum testosterone levels:
Compared to control (1.60 ng/mL), the rats given 1g/kg onion juice per day had serum testosterone levels of 5.017 ng/mL – a difference of 314%.
And these results appear to be confirmed in at least two other studies.
In this study, for example, onion juice was found to improve copulatory behavior in male rats and counteract the effects of low testosterone induced by paroxetine.
The authors of another study also report similar effects:
“There was maximum Serum total testosterone level in the onion group”
What about human testosterone levels?
As yet, the effects of onions and onion juice on human testosterone levels haven’t been extensively studied.
But for a 75kg human to get the same effects as the rats in the 1g/kg group you’d need 75g of onion juice. A typical onion is around 90% water1 and weighs roughly 250g. So, an onion a day for 20 days is likely to be more than enough to achieve the same concentration as the rats with 314% increased testosterone.
Of course, this is all highly speculative. Rat metabolism is very different to human metabolism. And who’s to say if these effects even transfer over to humans anyway?
Nevertheless, some anecdotal reports online report positive results. Some self-experimenters are even taking it upon themselves to get blood work done. And while none have seen the kinds of 300%+ results seen in the rat study, there are examples of increased testosterone increases and estrogen reduction.
It’s speculated that antioxidants in onions counteract the damaging effects of free radicals in the testes. This may explain the improved sperm quality and increased testosterone seen in the rat study.
Reasons to eat more onions
Even if onions don’t quite boost testosterone by 300%, there’s good reason to make them a regular part of your diet.
Onions are rich in vitamins, minerals, phytochemicals and antioxidants – many of which are hard to find in other vegetables. In particular, they’re a good source of quercetin, vitamin C and sulfides. As such, onions have a long history of use in traditional medicine.
And this interest continues to this day. Onions are being studied for their potential to treat serious health disorders including:
For most people, the only side effects from onions will be running eyes and possibly bad breath.
However, the phytochemicals in onions can suffer severe allergic reaction in some individuals. Besides eye irritation, symptoms can include anaphylaxis, bronchial asthma and contact dermatitis.
The health benefits of onions are strongest when consumed raw.
Do onions increase testosterone?
Probably. But by how much is hard to say.
The effects in rats are hard to dispute. And while this doesn’t automatically mean onions will have the same testosterone-boosting effects in humans, it seems highly likely there will be similar effects across the species.
As for a 300%+ increase, that seems unlikely.
Regardless, it’s well worth picking up some onions next time you go shopping. They’re rich in antioxidants, phytonutrients and polyphenols. They’re linked with a whole host of health benefits and they can taste pretty good too.