Vitamin D and Oestrogen Balance in Men: What the Canguven 2017 Study Revealed

When most people think of vitamin D, they picture bone health, immunity, or time in the sun. But emerging research suggests vitamin D may play an important role in male hormone balance—specifically in reducing elevated oestradiol levels, a pattern often described as oestrogen dominance in men.

A key study in this area is the work of Canguven et al. (2017), which examined how vitamin D supplementation affects sex hormones in middle-aged, vitamin-D-deficient men. The findings are highly relevant for men seeking natural ways to optimise testosterone-to-oestradiol ratios and support metabolic and reproductive health.

What the Study Found

In the 2017 clinical study, men with low vitamin D were given ergocalciferol (vitamin D₂) supplementation for 12 weeks. After the intervention, researchers observed:

✔ A significant decrease in oestradiol (E2) levels

Vitamin D supplementation lowered circulating oestradiol, helping shift hormone balance in a favourable direction for male physiology.

✔ Improvements in sexual health markers

The men experienced improvement in erectile function and other androgen-related symptoms, suggesting downstream benefits of reducing excess aromatase activity.

✔ A normalising effect on hormonal ratios

Although total testosterone did not dramatically change, the T/E2 ratio improved because oestradiol decreased. This ratio is a meaningful marker in addressing symptoms of estrogen dominance in males.

Why Might Vitamin D Lower Oestradiol?

Several mechanisms may explain the findings:

1. Vitamin D may down-regulate aromatase

Aromatase is the enzyme that converts testosterone into oestradiol. When aromatase is overactive—due to inflammation, higher body fat, poor diet, or environmental exposures—men can experience elevated oestrogen levels. Vitamin D appears to help regulate this enzyme.

2. Vitamin D improves metabolic health

Better insulin sensitivity and reduced inflammation both decrease aromatase activity and support healthier testosterone levels.

3. Vitamin D supports the hypothalamic-pituitary-gonadal (HPG) axis

Adequate vitamin D is associated with optimal hormone signalling and improved androgen responsiveness.

What This Means for Men Experiencing Oestrogen Dominance

Oestrogen dominance in men is increasingly recognised as a contributing factor in:

• Weight gain

• Fatigue

• Mood changes

• Decreased libido

• Erectile dysfunction

• Gynecomastia

• Loss of muscle mass

While no single nutrient is a cure-all, the Canguven 2017 research highlights that optimising vitamin D—particularly in those who are deficient—may help reduce oestradiol and restore healthier hormonal balance.

This supports the broader functional-medicine view that nutrients matter, and that hormone patterns often improve when underlying nutritional and metabolic factors are addressed.

Want to Learn More About Foods and Nutrients That Influence Oestrogen in Men?

If you’re interested in a deeper look at how dietary foods and nutrients affect oestrogen dominance in males, I encourage you to read Dr D. Michael Elliott’s newly published systematic review in Human Nutrition & Metabolism:

“Influence of Dietary Foods and Nutrients on Oestrogen Dominance in Males.”

This peer-reviewed paper brings together the current evidence on how foods such as coffee, cruciferous vegetables, fibre, vitamin D, soy, nuts, and more influence oestradiol, SHBG, testosterone, and aromatase activity in men.

It’s an excellent next step if you want to understand how diet, lifestyle, and targeted nutrients can meaningfully support hormone health.