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Everything You Need to Know About Vitamin D Deficiency in 2023

 Eric First, M.D., FAIS and Matthew Roberts, Ph.D.

Vitamin D is a fat-soluble nutrient that plays an important role in maintaining several aspects of your overall health. In this post, we’ll be discussing everything you need to know about vitamin D deficiency. 


Vitamins for Stress | Immunity | Vitamin D | L-Theanine | Stress Pills | Calm | Focus | Sleep | Relaxation | Not Gummy |

A nutrient deficiency occurs when your body isn’t getting enough of a specific vitamin or mineral. Your body needs nutrients like vitamin D to function properly, and when you do not get enough D vitamins from food, sunlight, and supplements, you run the risk of developing a deficiency. 

A vitamin D deficiency can cause some troublesome, uncomfortable, and highly problematic side effects and contribute to medical conditions like rickets in children, osteomalacia in older adults, and endocrine conditions such as hyperparathyroidism. 

There is even evidence that low vitamin D can lead to changes in blood pressure, heart disease, and multiple sclerosis. It is essential to get enough of this important nutrient each day. Vitamin D deficiency is also called hypovitaminosis D, and it has a high prevalence across the globe.

Vitamin D deficiency is an extremely common problem – over 1 billion people worldwide have insufficient vitamin D levels. 

In this post, we’ll tell you everything you need to know to keep yourself from becoming deficient in this vital nutrient.

Where Do You Get Vitamin D?

Your body absorbs vitamin D (specifically vitamin D3) from sunlight, but there are also numerous other sources of the nutrient. There are also multiple types of vitamin D – namely D2 and D3. D2 is found in a variety of plant and animal-derived foods, but D3 is primarily only found in meat and other animal products.

In addition, your body also produces vitamin D on its own. Unlike water-soluble vitamins, which cannot stay within your body for long, fat-soluble vitamins – D, A, C, E, and K – can all remain in your system for long periods of time. This makes the risk of a deficiency less immediate – your body can go for a long time without showing signs or symptoms of a vitamin D deficiency. However, it is still essential to avoid getting anywhere near the point where a deficiency would be a risk. 

Some of the most common dietary sources of vitamin D are fatty fish like mackerel, egg yolks, orange juice, dairy products, and mushrooms. Vitamin D2 is also found in a number of fortified foods, including grains and non-dairy milk.

Vitamin D and Calcium

Vitamin D has a special relationship with another important nutrient – calcium.

Your body’s vitamin D absorption and your absorption of calcium are mutually dependent. This means that if you are deficient in either of these nutrients, you are likely to develop a deficiency in the other. When there is not enough vitamin D in your diet, your body cannot properly absorb calcium and vice versa. Thus, one of the most common signs of a vitamin D deficiency is a calcium deficiency. This is especially common in older people.

Both vitamin D and calcium are essential for maintaining strong bones and teeth. Without enough of these nutrients, you will be at a far greater risk of developing osteoporosis (loss of bone density), bone pain, muscle weakness, arthritis, tooth decay, and other serious problems. 

Sunlight and Vitamin D 

Vitamin D is often referred to as “the sunshine vitamin.” This is because your skin generates vitamin D3 (cholecalciferol) in response to sun exposure. For this reason, vitamin D deficiencies are thought to be more common in the colder, darker months of the year. In parts of the world where fall and winter tend to bring colder weather and shorter days, sun exposure occurs much less frequently for many people. 

This lack of sunlight can lead to what is often called the “winter blahs,” but is formally known as seasonal affective disorder – or SAD for short. Seasonal affective disorder is a common issue that partially stems from lower sun exposure during the winter months. Since your body is absorbing less vitamin D from the sun during the colder, darker months of the year, you may experience one of the most well-known symptoms of vitamin D deficiency – depression.

There is a link between low-grade depression and vitamin D deficiency. The authors of a recent study suggest “Effective detection and treatment of inadequate vitamin D levels in persons with depression and other mental disorders may be an easy and cost-effective therapy which could improve patients’ long-term health outcomes as well as their quality of life.”  Vitamin D is a vital nutrient for your emotional health, and it can be especially helpful to include a D supplement in your daily routine during the winter when you’re getting sunlight less consistently.

What Causes Vitamin D Deficiency? 

There are numerous factors that may make you more vulnerable to developing a vitamin D deficiency. Some of the most common causes of becoming deficient in this important nutrient are listed below.

Minimally Diversified Vegan Eating 

When approached correctly, a vegan diet can provide you with all the nutrients you need for optimal health. Aside from anyone with specific dietary restrictions, everyone can benefit from eating plenty of fruits, vegetables, whole grains, legumes, and other plant-based foods on a daily basis. These foods are excellent sources of vitamins and minerals. 

However, not all of the nutrients that your body needs are easy to find in plant-based foods. In fact, some vitamins – B12 and D3, to be exact – are only found in animal products. This means that without supplements, the only vegan-friendly source of D3 is the sun.

If you adhere to a vegan lifestyle, it’s best to refrain from making sunlight your only source of vitamin D. Instead, be strategic with the way you include this vital nutrient in your diet. You can get plenty of plant-based D2 from mushrooms and fortified grains, and you can easily find plant-based D3 supplements to complement your well-balanced diet.

An Overall Poor Diet 

If you eat a diet that is lacking in essential nutrients – primarily fried food, refined sugar, and the like – you’re far more likely to become deficient in vitamin D. Junk food may taste great, but it’s typically loaded with processed ingredients and unimpressive in the nutrition department. Highly processed, sugary, fried treats might go down easy, but they’ll leave your body lacking the nutrients it needs. 

You need to eat healthy foods with vitamin D2 (ergocalciferol) to maintain a healthy vitamin D status. 

To avoid developing a vitamin D deficiency – and to keep yourself from becoming deficient in other essential nutrients – make sure to eat healthy, whole, unprocessed foods as often as possible. It’s okay to slip up from time to time, and you don’t have to deny yourself the occasional treat. However, the foundation for your diet should always be nutrient-dense, healthy food.

Lack of Sunlight 

If you rarely spend time soaking up the sun, you may be at greater risk of developing a vitamin D deficiency. Since your body produces D3 in response to sun exposure, getting some ultraviolet B (UVB) rays each day is one of the best ways to keep a deficiency from developing. 

It is more difficult for people with high melanin content to absorb vitamin D from the sun because melanin is extremely photoprotective. For this reason, older adults with darker skin may be at a high risk of vitamin D deficiency. 

However, it’s always essential to wear plenty of sunscreen whenever you’re getting direct sun exposure. That way, you’ll protect yourself from sunburns and skin cancer.

Other Nutrient Deficiencies 

If your body is lacking other vitamins and minerals that it needs, you may be more likely to become deficient in vitamin D. Two nutrient deficiencies that have been linked to poor absorption of vitamin D are iron and calcium. Getting enough of these nutrients is essential for keeping your vitamin D absorption at optimal levels.

Some medical conditions such as Crohn's disease, and Celiac disease affect your body's ability to absorb vitamin D from food (malabsorption), putting patients at higher risk of vitamin D deficiency. People with risk factors including liver disease, obesity, people who take cholesterol-lowering drugs, people who recently underwent weight loss surgery, people with elevated parathyroid hormones, and kidney disease are also more likely to have a low vitamin D intake, often because vitamin D synthesis has been disrupted in their bodies.

When Should You Talk to Your Doctor? 

If you suspect that you have a vitamin D deficiency, it’s always a good idea to consult a healthcare professional. Your doctor can determine whether you are deficient in vitamin D by giving a serum 25-hydroxyvitamin D blood test. 

If your doctor concludes that, based on the results of your blood test, you are lacking vitamin D, they will help you assemble an effective treatment plan. It is important to speak to a doctor if you suspect you have low levels of vitamin D, as too much vitamin D can also cause problems. Vitamin D toxicity is rare, but a high dose of vitamin D can cause hypercalcemia. 

If you are vitamin D deficient or have a severe vitamin D deficiency, your doctor will be able to help you create a treatment plan. However, if you're simply looking to ensure that you have the right amount of vitamin D in your diet, vitamin D supplements and multivitamins are a safe and healthy way to prevent vitamin D insufficiency. 

Generally, the most effective treatments for vitamin D deficiency are lifestyle changes. Sunlight exposure, adding vitamin D-rich foods to your diet, and taking a high-quality supplement can all be reliable ways to reverse the effects of the deficiency and get your nutrient levels back on track. 

The symptoms of a vitamin D deficiency typically go away once your levels of the nutrient are back to normal. However, if your symptoms persist, it’s always wise to follow up with your doctor – these symptoms may be connected to something that requires more medical attention.


Vitamin D is an essential nutrient, and if you don’t get enough of it from foods, supplements, and the sun, you can run into some big problems. It’s a vital nutrient for mood regulation, bone health, calcium absorption, the prevention of cardiovascular disease, immune system support, and more, and that’s why we’ve included it in our signature R3SET formula. 

Our Calm capsules include high-quality vitamin D3, along with a variety of other highly beneficial stress-supporting botanical ingredients.

We chose to make vitamin D3 a key part of our Calm formula because of its integral role in maintaining healthy immune system function. The combination of vitamin D with ingredients like chamomile, GABA, L-Theanine, and more may make a difference in your overall mental well-being*. We recommend pairing our Calm capsules with our Unwind supplements which also contain Vitamin D – this combination is an all-day and evening support system.

If you’re curious about nutrients like vitamin D, the link between nutrition and stress, and how natural ingredients can help to keep you focused, calm, and alert throughout the day, make sure to visit the R3SET blog. There, you’ll find helpful articles that cover a variety of topics, including vitamin D. 

 *These statements have not been evaluated by the Food and Drug Administration (FDA). This product is not intended to diagnose, treat, cure or prevent any disease



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