Here’s Why Every Nutrition Scientist Has Their Eyes on This Test-Boosting Nutrient

It wouldn’t be the world of health and nutrition without a new testosterone-boosting nutrient appearing out of nowhere, claiming to be the next big thing for your hormones.

And while some of them are built on false promises and clever marketing, some occasionally live up to the hype and make a real difference. Indole-3-Carbinol is the new kid on the block

In the battle against low T, this is the one ingredient that deserves its time in the spotlight. And in this article, we’ll tell you why.

Here’s everything you need to know about indole-3-carbinol, its health benefits and its anti-estrogenic effects…

What is Indole-3-carbinol?

Indole-3-carbinol (I3C) might sound like Disney’s new Star Wars franchise character. But unless this years’ intergalactic escapade features a robot made of broccoli, it’s unfortunately not.

Most people are aware that dark green vegetables are healthy. You know already that getting your 5-a-day is important, because vegetables provide maximum vitamins, minerals and other nutrients in very few calories.

I3C is formed during the digestion of a chemical called glucobrassicin, and as the name suggests, I3C is found in brassica and cruciferous vegetables – broccoli, cabbage, collard greens and everyone’s favourite health food, kale.

Anti-estrogenic effects of brassica vegetables

Brassica foods contain a chemical called diindolylmethane (DIM). It’s a compound famed for its health-giving benefits. DIM is a metabolite of I3C, formed through a ‘condensation reaction’ when different I3C molecules combine during digestion.

Both I3C and DIM act on estrogen receptors, inhibiting the process of aromatization.

Not too familiar with aromatization?

This is what you need to know.

At any one time, some of the testosterone in your blood is dragged from its target tissue and converted to estrogen. You might think it, but this is actually a good thing. An enzyme called aromatase scours your body like a flashlight-wielding security guard looking for pesky kids.

When it senses that testosterone levels are higher than normal, it converts some of the excess to estrogen. And that helps to keep your testosterone levels from going too high and causing all kinds of side effects.

Wait, isn’t estrogen a ‘female’ hormone?

Yep. Well, kind of anyway.

It’s true that estrogen is the primary female hormone. But in men it’s also important for regulating health.

In optimal amounts, estrogen maintains bone health and helps to keep your heart healthy. Strangely, a specific type of estrogen called estradiol is important for maintaining your sexual function.

Think of estrogen and testosterone being on different sides of a seesaw. When both perfectly balanced your body works at its best.

The problems start when it gets too high… or too low.

Low testosterone leads to high estrogen

From the age of around 30, men experience a 1-2% decrease in testosterone level each year – by the time you reach 45, there’s a 40% chance your testosterone levels will be clinically low.

Signs of high estrogen and low testosterone include:

  • Gynecomastia – growth of man boobs.
  • Infertility – testosterone is the primary driver of male fertility, libido and sex drive.
  • Constant tiredness, loss of energy and motivation.
  • Mood changes – anxiety, depression, generalized stress.

This is where I3C comes in.

Because it’s been found in numerous clinical trials to reduce estrogen so that healthy hormonal balance can be achieved.

The Health Benefits of Indole-3-Carbinol Supplementation

As a subject of hundreds of biomedical research projects, I3C is fast becoming the most valid anticarcinogenic, atherogenic antioxidant-rich nutrient around.

I3C is causing a excited stir in the health and medical community. It’s fast becoming the nutrient of choice for scientific research, based on its reliability and versatility.

Maybe mom was right – eating your greens is the key to health. Only now you don’t have to force down your vegetables, you can opt for a health-boosting supplement instead.

In supplement form, indole-3-carbinol been shown to benefit a number of health markers:

  1. Potential anti-cancer properties – studies have shown I3C to be reliable for treating cancer, being able to slow down tumor progression and regulate the genes responsible for promoting cell proliferation and growth. In fact, it’s so effective, the National Institute of Health (NIH) are currently on advanced trials to assess its reliability as a possible cancer preventative medicine.
  2. Improves symptoms of fibromyalgia – a disorder characterized by muscle pain, fatigue, stiffness and extreme sensitivity – has been shown to improve with I3C supplementation. In some research projects, 500 mg of the glucobrassicin extract showed a 20% improvement in physical impairment symptoms and quality of life over a 30-day period.
  3. It slows down the aging process. If kale and sprouts aren’t your thing, bear this in mind – I3C has been shown to regulate your autoimmune function, reduce inflammation and ¬†help your body produce antibodies to fight off infection and illness. It’s even been shown to prolong life span in animal studies too.

Indole-3-carbinol and testosterone – an effective estrogen blocker

Testosterone is tightly regulated in 3 different ways:

  • Direct testosterone production by the Leydig cells of the testes.
  • Indirect stimulation of the Leydig cells by the brain via luteinizing hormone.
  • Regulation of aromatization and estrogen levels.

Some nutrients can ramp up testosterone directly. These include vitamin D3 and zinc. Others such as D-aspartic acid stimulate the release of luteinizing hormone, which in turn stimulates testosterone production in the testes.

That just leaves estrogen levels to take care of, and before you know it you’re an alpha male with a lean strong physique, with confidence and assertiveness to match.

Indole-3-carbinol decreases estrogen proliferation

According to one clinical trial published in the prestigious Journal of Nutrition;

“I3C causes growth arrest and increased apoptosis and ameliorates the effects of estrogen”.

In plain English that means it not only slows down the rate of growth of estrogen, but kills it altogether. This leaves plenty of room for testosterone to flourish and bathe your cells with androgen goodness.

Estrogen metabolism increases with indole-3-carbinol supplementation

In a similarly beneficial study, 7 men were given 6-7 mg of i3C per kilogram of body weight, supplementing it for only 1 week. During that short, 7-day period though, metabolism of estrogen increased, with more being excreted from the body during urination.

They were literally peeing the estrogen from their bodies!

Interestingly, the same dose of I3C was associated with a chemoprotective effect in women when taken for 2 months, so could help to reduce the risk of cancer cell growth too.

Ic3 supplementation reduces estrogen ‘potency’

Indole-3-carbinol supplementation is able to convert potent estrogen molecules into less testosterone-destroying ‘weak agonists’.

In one very interesting study from the Journal of Steroid Biochemistry and Molecular Biology, a protein that regulates aromatization called CYPB1B was down-regulated after I3C supplementation, while a related enzyme known as CYP1A2 was also improved.

Why supplement indole-3-carbinol and not just DIM?

This is a question that’s asked more often than you’d think. If DIM is a metabolite of its parent molecule I3C, formed during digestion, why not just supplement DIM?

The problem with this idea is that a lot goes off during digestion. It’s not just a simple matter of input and output.

Not only does I3C form DIM during digestive process, it also forms other important compounds such as IAN, Ni3C and ICZ which all play their part in regulating health. Having a team of nutrients to fight a battle against health risks will always be a better game plan than sending out a single soldier.

DIM bioavailability can be poor on its own

The problem with taking DIM on its own is that it doesn’t transport to your cells that effectively.

When it’s broken down from I3C, it uses the other nutrients made during its condensation reaction as a shuttle, helping it reach your cells at breakneck speed and with a screeching hand brake stop.

Bottom line is that the sum is greater than the parts. As is the case with most nutritional interventions and supplements.

Can Women take I3C?

Let’s take a look at some of the research into this;

I3C has been shown to be a negative regulator of estrogen and therefore could prevent the development of estrogen-enhanced cancers (breast, endometrial and cervical). (source).

In fact, most studies using female participants have focused on reducing cancer risk, rather than for athleticism or general health. Tolerable daily amounts have been observed with both 400 mg and 800 mg, with 400 mg offering a maximal protective effect (source).

No adverse reactions in females using 400 mg daily for 6 weeks (source).

No adverse reactions in females at high risk of breast cancer;

“The results in this study suggest that I3C at a minimum effective dose schedule of 300 mg per day is a promising chemopreventive agent for breast cancer prevention.”(source)

Long-term, chronic use of I3C may increase the risk of osteoporosis in post-menopausal women, however this is an under-researched area.

Pregnant women should avoid taking I3C as a supplement due to its estrogen inactivation effect, but to be fair pretty much any decent supplement on the market will advise pregnant women not to consume it anyway.

If you are taking birth control there may be some interference, so consult with your physician before use.


Indole-3-carbinol is a phyto-compound found in cruciferous, brassica vegetables such as broccoli and kale.

As a health-promoting nutrient, I3C has been shown to have anti-cancer properties, slow down cellular aging and improve symptoms of some inflammatory disorders too.

The main benefit linking indole-3-carbinol to testosterone levels is that it acts as a potent anti-estrogenic, shown in numerous studies to not only slow down the process of aromatization, but to help eliminate estrogen from the body too.

Alongside direct testosterone-boosting nutrients, I3C is an important male hormone support supplement that offers many additional health benefits.

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