Vitamin D deficiency

Explore the causes, symptoms, and health consequences of vitamin D deficiency in men, including its impact on testosterone levels, bone density, and immune function. Learn how to identify and correct low vitamin D status for optimal health and performance.

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The essentials for vitamin d deficiency — then explore the latest posts below.

Brain fog in men: Best vitamins for brain fog and memory, plus supplements that actually help

Dr. Jonathan Pierce, PhD: Clinical Psychologist & Neuroscience Specialist

Jan 20, 2026 · 13 min read

The best vitamins for brain fog and memory are usually the nutrients you are deficient in, most often B vitamins, vitamin D, omega 3 fats, magnesium, and antioxidant nutrients. The smart play is to treat brain fog like a clue, get the right labs, then use targeted brain fog supplements instead of guessing. “In men, ...

Can Vitamin D impact testosterone?

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Oct 28, 2025 · 15 min read

Vitamin D can modestly raise testosterone in men who are truly vitamin D deficient (25-hydroxyvitamin D below 20 ng/mL), likely because the testes contain vitamin D receptors and activation enzymes that may influence Leydig cell testosterone production. Here is how to tell when correcting vitamin D is a meaningful lever. It also explains when low ...