Vitamin D

Explore the critical role of vitamin D in testosterone production, bone health, immune function, and overall male performance. Learn about optimal levels, supplementation strategies, and how deficiency may be silently undermining your health goals.

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

Best immunity boosting foods for men: What to eat to support your immune system year-round

Best immunity boosting foods for men: What to eat to support your immune system year-round

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Feb 13, 2026 · 13 min read

The best immunity boosting foods are the ones that reliably provide the micronutrients and bioactive compounds your immune cells use to build barriers, signal threats, and resolve inflammation. This guide breaks down the highest-impact foods and shows how men can turn them into a simple, repeatable “immunity plate” for work, travel, and training. Written by: ...

What is the best supplement for inflammation? The 8 options with the strongest evidence

What is the best supplement for inflammation? The 8 options with the strongest evidence

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Jan 21, 2026 · 13 min read

There is no single best supplement for inflammation for every man, but a small group has the strongest human evidence for lowering inflammatory signals or improving inflammation driven symptoms. This guide breaks down the best supplements for inflammation, what they do in the body, and how to choose based on your goals and lab results. ...

Which essential biomarkers runners should track? The lab numbers that predict fatigue and low testosterone

Which essential biomarkers runners should track? The lab numbers that predict fatigue and low testosterone

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Dec 04, 2025 · 15 min read

The essential biomarkers runners should track include vitamin D, iron and ferritin, magnesium and potassium, C reactive protein, testosterone, cortisol, blood glucose, and performance markers like VO2 max, lactate threshold, and resting heart rate. When those numbers drift, your training can feel harder, recovery slows, and injury risk rises even if your mileage looks “perfect.” ...

Can Vitamin D impact testosterone?

Can Vitamin D impact testosterone?

Dr. Susan Carter, MD avatar
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 ...

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