Vitamin D Side Effects: What To Know About Taking Vitamin D Supplements

Here's a breakdown of what to know about vitamin D supplements, the effects of vitamin D in the body, and how to make sure your routine is working for you. 

In fact, according to Sina Gallo, Ph.D., RDN, a nutritional sciences professor at the University of Georgia, the reality is that it's actually quite difficult to get all of the vitamin D you need just from diet and sun alone.*

Integrative dietitian Whitney Crouch, RDN, CLT, recommends taking a vitamin D supplement that provides up to 5,000 IU of vitamin D3 (since that's the body's preferred form at a dose known to achieve sufficiency)—and ideally one that also contains healthy fats to support absorption.* (Vitamin D supplements that also provide high-quality healthy fats are harder to find, so mbg formulated vitamin D3 potency+ to fill the gap.) For more specific recommendations, check out our vitamin D supplement roundup.

As mbg's vice president of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, explains further, "Just because vitamin D is fat-soluble by design doesn't mean it's toxic at clinically useful doses, like 5,000 IU. That's a complete misnomer. In reality, true reports of vitamin D toxicity with clinical evidence2 have occurred at 200,000 to 300,000 IU per day—yes, you read that correctly—in vulnerable populations like infants of folks with medical issues." So, rest assured.

Adding a vitamin D supplement to your routine can help you support healthy vitamin D levels, which promotes bone, teeth, muscle, immune, and whole-body health.* Here are just a few of the positive side effects you may experience as you strive for optimal vitamin D intake:*

Because vitamin D facilitates (actually, it's critical for) the body's absorption and balance of calcium and phosphorus, supplementing your vitamin D intake can support these essential minerals in the various roles they play in the body, including bone health (which includes your teeth, too!), according to Gallo.*

Since calcium also plays a role in muscle function, checking that vitamin D box helps there, too. In fact, a comprehensive review of clinical trials5 revealed a link between supplementing with vitamin D3, specifically, and muscle strength.* Good news for anyone looking to support their movement routine!

An exciting area of research, clinical trial research clearly demonstrates that vitamin D sufficiency and supplementation (to achieve sufficiency) have a positive impact on long-term glycemic control6, insulin sensitivity7, and even one's metabolic health trajectory8.*

Science has established a pretty strong connection between vitamin D and mental well-being.* In fact, according to a 2020 review9, multiple clinical studies have identified the link, even highlighting that those with mood health needs have been seen to have lower vitamin D levels. Other evidence suggests that vitamin D supplementation may help reduce negative emotions10.*

According to the National Institutes of Health11, some of the first signs of hypercalcemia include:

If you experience any of these, check in with your health care provider, stat.

Because so many people don't come close to getting enough vitamin D through food and sunshine alone, a high-quality supplement can be incredibly helpful (if not essential) in achieving healthy vitamin D levels and the corresponding immune, bone, muscle, and whole-body benefits.*