On a typical sunny day, your body may produce up to 25,000 international units (IU) of vitamin D, although many people aren’t in the sun enough to optimize their vitamin D levels. However, we strongly recommend getting your vitamin D from proper sun exposure, if possible, as it provides benefits beyond vitamin D optimization.

Higher levels of vitamin D may even serve as a marker for healthy sun exposure, which in turn may be responsible for many of the health benefits, which include reduced risk of cancer and increased longevity, attributed to vitamin D. Regular sun exposure, for instance, enhances production of melatonin — a potent anticancer agent.

Near-infrared rays from the sun penetrate deep into your body and activate cytochrome c oxidase, which in turn stimulates the production of melatonin inside your mitochondria. Your mitochondria produce ATP, the energy currency of your body. A byproduct of this ATP production is reactive oxidative species (ROS), which are responsible for oxidative stress.

Excessive amounts of ROS will damage the mitochondria, contributing to suboptimal health, inflammation and chronic health conditions such as diabetes, obesity and thrombosis (blood clots). But melatonin essentially mops up ROS that damage your mitochondria. So, by getting plenty of sun exposure during the day, your mitochondria will be bathed in melatonin, thereby reducing oxidative stress.

If you’re unable to get adequate sun exposure each day, vitamin D supplementation may be necessary. Keep in mind that 20 ng/mL, which is often used as the cutoff for vitamin D deficiency, has repeatedly been shown to be grossly insufficient for good health and disease prevention, which means the true prevalence of people without optimal levels of vitamin D is even greater.

The only way to determine how much sun exposure is enough and/or how much vitamin D3 you need to take is to measure your vitamin D level, ideally twice a year. Once you’ve confirmed your vitamin D levels via testing, adjust your sun exposure and/or vitamin D3 supplementation accordingly. Then, remember to retest in three to four months to make sure you’ve reached your target level.

The Optimal Vitamin D Level for Cancer Prevention

The optimal level for health and disease prevention, including cancer prevention, is between 60 ng/mL and 80 ng/mL (150-200 nmol/L), while the cutoff for sufficiency appears to be around 40 ng/mL. In Europe, the measurements you’re looking for are 150 to 200 nmol/L and 100 nmol/L respectively.

It’s important to remember that calcium, vitamin D3, magnesium and vitamin K2 must be properly balanced for optimal overall health. Your best and safest bet is to simply eat more calcium-, magnesium- and vitamin K2-rich foods, along with sensible sun exposure.

We recommend: Hippocrates Vitamin D3: 500 Capsules The Australian Register of Therapeutic Goods allows us to inform you that Vitamin D: Assists in maintenance of general wellbeing. Helps calcium absorption. Calcium deficiency can lead to osteoporosis. May assist with mineralization of bones and teeth. Promotes healthy functioning of the immune system.