Vitamin D: Are You Getting Enough?

If you want to improve both your bone and mental health, vitamin D (the sunshine vitamin) is your new best friend! 

Learn everything you need to know about vitamin D in this article, including how we get it, how our bodies use it, and how much your body needs for optimal health.

Before we get into how, here are some little-known facts about vitamin D.

• Vitamin D is fat-soluble and requires the presence of fat for absorption.
• Vitamin D is constantly being modified into active and inactive forms.
• Vitamin D is not technically a vitamin, it’s a hormone.
• Chemically speaking, it’s more of a ‘steroid’ hormone.
• Vitamin D₂ and Vitamin D₃ are not equal.

How We Get It

Sunlight

It really is no secret.

Sunlight is your friend (to some degree)! The sun makes us feel good, partially because we get vitamin D from it. But how!?

When UVB rays hit our skin, a series of chemical reactions occur to convert the provitamin called 7-dehydrocholesterol, which is naturally found in human skin, to vitamin D.

Foods and Supplements

Vitamin D is also found in our foods and supplements. Chemically speaking, when we consume vitamin D, it’s usually in the form of Vitamin D₂ and Vitamin D₃.

Inactive vs. Active Vitamin D

Whether from sunlight, foods, or supplements, the vitamin D we take in is always inactive. That means our body cannot use it in those forms and must convert it to a usable form.

The first step in this conversion is done in the liver, which slightly modifies the vitamin D to something called 25-hydroxyvitamin D or 25(OH)D or cholecalcidiol. The kidneys complete the second step, where calecalcidiol is modified to its most active form called 1,25 dihyroxyvitamin D or 1α,25(OH)2D3 or calcitriol.

That’s a lot of chemistry, I know. To summarize quickly, here are the most common forms of vitamin D.

The Various Forms of Vitamin D

25(OH)D. Also known as Calcifediol. This inactive form of Vitamin D is an intermediary or metabolite. If a deficiency is suspected, doctors order labs that look at circulating levels of this form of vitamin D.

Vitamin D₂. Also known as Ergocalciferol, this form of vitamin D is an inactive metabolite of D. It is found in foods and supplements, and while it easily converts to the active form, it’s not the most efficient in raising and sustaining vitamin D levels.

Vitamin D₃. Also known as cholecalciferol, is the most common form we hear about. It is another inactive form of Vitamin D but is known to exert the most influence on overall vitamin D status.

Calcitriol. The only active form of Vitamin D. Once it’s in this form, our bodies utilize it in a number of different ways.

Additional Nutrients

The interactions between nutrients, and the physiological effects these interactions, can cause are what makes the human body and nutrition so interesting!

Pairing nutrients together is sometimes essential but it goes beyond just nutrients. Other compounds found naturally within food can also impact the way our body absorb and utilize nutrients (also known as bioavailability). In the case of Vitamin D, there are three nutrients heavily involved and worth talking about: Fat, Calcium and Magnesium.

Fat

Vitamin D, from foods and supplements, is a fat-soluble vitamin, meaning is best absorbed in the presence of fat. So, consuming fatty fish, or taking vitamin D supplements from marine fish oil, allows for the best absorption rates.

But remember when I said that Vitamin D is made from 7-dehydrocholesterol and that it’s more of a steroid hormone? Well, that’s because vitamin D is, itself, a type of fat. Cholesterol, a type of fat often associated with cardiac health, is the base material for all steroid hormones, including vitamin D. In the skin, the sun converts the cholesterol to D3 and in the digestive tract, vitamin D is absorbed as cholesterol. Note the -ol on the end of all the terms listed above.

I would be remiss if I also didn’t put in a plug for the double benefit of vitamin D consumed from fatty fish. Vitamin D from marine sources also gives you a side dish of Omega-3s, another mood boosting nutrient!

Calcium

As an essential electrolyte, calcium helps maintain homeostasis through water balance and electrical activity. Calcium is also an essential ‘building block’ in the formation of bones.

In its inactive form, vitamin D3 aids calcium absorption at the intestinal wall. More specifically, D₃ acts upon calcium-specific transport proteins or aids in passive diffusion across the intestinal lining.

Vitamin D also helps maintain adequate calcium and phosphorus levels in the blood and aids in mineralization. Without it, our bones would be brittle and misshapen; children may develop Rickets, and adults may develop osteoporosis.

Magnesium

When we take in adequate amounts of magnesium, we increase vitamin D’s bioavailability. Magnesium is required during the conversion of vitamin D to its active form and is involved in cellular binding during bone mineralization.

If you are considering supplementation with Vitamin D, you may also want to check your Magnesium levels. Many people have insufficient levels of magnesium, which may reduce vitamin D bioavailability. I wouldn’t want you to waste your money.

How We Use It

Bone Mineralization

The largest role that Vitamin D has in our body is its relationship with calcium and its ability to build and maintain strong bones. vitamin D is required for the absorption of calcium and helps to maintain proper levels within the blood. In addition, vitamin D is actively involved in the mineralization of bones. Without it, we’d have wonky and flaky bones. Vitamin D deficiency has been linked to Rickets in children and osteoporosis in adults.

Vitamin D and calcium are also helpful in preventing muscle spasms and may even help to strengthen them since they have vitamin D dependent receptors to help uptake nutrients. Additionally, healthy muscles are necessary for building strong bones.

Inflammation and Immune Response

Vitamin D’s role in our immune system is vast. Vitamin D is incorporated into cell walls and acts upon receptors that receive chemical messages from other cells.

In the immune system, those receptors receive messages to produce certain things that fight illness, injury, or infection or repair damaged tissues.

For example, animal models have shown vitamin D can moderate the levels of inflammatory cytokines. This protein messenger orchestrates the immune response but, over time, can build up, causing adverse effects (i.e., pain with no injury).

Finally, more research is needed to tease out the effects of vitamin D on the risk of cancer, but some studies indicate a slight reduction in mortality rate with adequate or higher levels of circulating 25(OH)D.

Heart Health

Vitamin D is a key player in cardiovascular health. It is associated with managing blood pressure because of its role in the renin-angiotensin-aldosterone system, and it’s heavily involved in cell growth, particularly vascular cell growth. Lastly, vitamin D is associated with inflammation, a condition known to negatively impact our vasculature.

Vascular dysfunction, arterial stiffening, left ventricular hypertrophy, and hyperlipidemia all appear to be linked to vitamin D deficiency.

Brain Function

In the brain, vitamin D is involved in many processes, including neurotransmitter production and cell signaling. Vitamin D also has roles in inflammation, a condition with cognitive and psychiatric implications.

In addition, poor mental health, particularly depression, may be improved with vitamin D due to its role in neurotransmitter production and inflammation, but research is insufficient in this area.

If you’ve ever experienced the ‘winter blues’, then you likely were experiencing mild Vitamin D deficiency, which research has linked to seasonal depression. You can read more about how in ‘Say Goodbye To The Winter Blues For Good.’

Glucose Metabolism

Vitamin D influences insulin secretion from beta cells in the pancreas and helps to reduce insulin resistance through vitamin D receptors in the muscles and liver. Due to these actions, vitamin D may positively affect type 2 diabetes though more research is needed before clinical recommendations can be made.

Deficiency

There are some situations that put people at greater risk for deficiency.

1. Exclusively breastfed infants. Surprisingly, human breast milk doesn’t contain Vitamin D, and exclusively breastfed infants are at risk of deficiency.
2. Advanced age. Older humans may be at risk of deficiency due to several factors, such as poor dietary intake, limited access to sunlight, and failing health.
3. Dark skin. Melanin, the pigment in our skin, absorbs UV rays and reduces the conversion of 7-dehydrocholesterol to D₃.
4. Limited sun exposure. Shorter days of winter, wearing full clothing, working indoors, and excessive use of sunscreen are lifestyle factors that make someone more susceptible to vitamin D deficiency.
5. Bariatric surgeries, Celiac, Crohn’s, or Ulcerative Colitis. These conditions affect the way our intestines absorb certain nutrients, increasing one’s risk of deficiency.
6. Obesity and Liver disease. Changes in the way our bodies absorb, utilize or convert vitamin D happens in obesity and liver disease.

When our serum levels of Vitamin D begin to drop, our bodies don’t operate optimally. Many signs and symptoms of vitamin D deficiency can be confused with other conditions, so it’s important to discuss any symptoms you may be experiencing with your medical doctor.

Signs you may not be getting enough Vitamin D include:

• Fatigue
• Not sleeping well
• Muscle weakness
• Bone pain or achiness
• Depression or feelings of sadness
• Hair loss
• Loss of appetite
• Getting sick more easily

Sources of Vitamin D

Sunlight is our number one source of vitamin D, but when access to sunlight is limited, we must turn to our foods and/or supplements.

Foods

Increasing fatty fish consumption to 2-3 times per week can be an easy way to increase your vitamin D intake; plus, you’ll get a bonus side of omega-3 fatty acids! Mushrooms, and fortified products like milk, can also be good dietary sources of vitamin D.

Fatty Fish include:

Supplements

With limited sunlight, whether related to lifestyle choices or seasonal climate changes, it can be challenging to obtain adequate amounts of Vitamin D through food alone.  Since tanning beds aren’t safe anymore (’cause they cause cancer), supplementation is the next best thing.

Vitamin D supplements, in the form of D₂ and D₃, are just as good as those from foods! Both forms are well absorbed and metabolized, but D₃ is slightly superior in increasing and maintaining serum vitamin D levels.

Should you also take Magnesium?

In addition to Vitamin D, you might consider adding magnesium because without sufficient amounts, you may not reap D’s full benefits and you’d be wasting your money. More importantly though, you may harming yourself.

Regarding harm. As previously discussed, vitamin D helps to absorb calcium, and by flooding your blood with calcium, you could disrupt your delicate electrolyte balance, put stress your kidneys, and cause calcification of soft tissues (think blood vessels!). This could lead to increased inflammation and cardiovascular events, the opposite of what we are trying to accomplish here.

The Recommended Dietary Allowance (RDA) for Magnesium is 310-320 mg per day for women.

Aim to increase your consumption of foods that are food of magnesium including, legumes, dark green leafy vegetables, nuts, seeds, whole grains, and fortified cereals.

How Much Is Enough

To avoid deficiency, aim for a total of 600 IU per day. This is the Recommended Dietary Allowance (RDA) for all adults, male and female.

Higher amounts of up to 4000 IU daily (the tolerable upper intake) are acceptable, but amounts exceeding that could lead to negative side effects, primarily hypercalcemia (too much calcium in the blood). Hypercalcemia can lead to disruptions in heart rhythms and the calcification of soft tissues like blood vessels. Consider your magnesium level as well; insufficient amounds may lend a hand in these adverse effects.

High doses, up to 50,000 IU/week, given under medical supervision, are used for certain situations and medical conditions. Never take this much on your own.

Excessive exposure to sunlight is not known to cause toxicity of vitamin D.

Although rare, signs of toxicity include:

There you have, ghouls! How will you get more Vitamin D?

See you at the beach, Witches!

Want to get involved? I’m looking to connect with people like you! Contact me with your ideas!

References

1. Vitamin D: Fact Sheet for Health Professionals. Accessed 12/12/2022 from LINK
2. Wesselink E, Kok DE, Bours MJL, de Wilt JHW, van Baar H, van Zutphen M, Geijsen AMJR, Keulen ETP, Hansson BME, van den Ouweland J, Witkamp RF, Weijenberg MP, Kampman E, van Duijnhoven FJB. Vitamin D, magnesium, calcium, and their interaction in relation to colorectal cancer recurrence and all-cause mortality. Am J Clin Nutr. 2020 May 1;111(5):1007-1017. doi: 10.1093/ajcn/nqaa049. PMID: 32190892; PMCID: PMC7198285. Full-Text Link
3. Norman AW. From vitamin D to hormone D: fundamentals of the vitamin D endocrine system essential for good health. Am J Clin Nutr. 2008 Aug;88(2):491S-499S. doi: 10.1093/ajcn/88.2.491S. PMID: 18689389. Full-Text Link
4. Ramasamy I. Vitamin D Metabolism and Guidelines for Vitamin D Supplementation. Clin Biochem Rev. 2020 Dec;41(3):103-126. doi: 10.33176/AACB-20-00006. PMID: 33343045; PMCID: PMC7731935. Full-Text Link