"Low levels of vitamin D in the population as a whole suggest that most people need to take a vitamin D supplement. This may be especially true for seniors, as the ability to synthesize vitamin D in the skin declines with age." - Andrew Weil
Introduction | Vitamin D | Types |Functions | Deficiency Symptoms | Synergism & Antagonism | How Much? | Supplements | Final Thoughts | Takeaway Points | References | Disclaimer
Introduction
Vitamin D3 is an essential fat-soluble nutrient our bodies require to maintain their functions. It is a member of the D vitamin family, along with D2 and D5. It impacts bone health, cardiovascular health, inflammation, insulin, cognitive functioning, and overall brain health. It is a key element for a strong immune system and plays a crucial role in calcium, magnesium, and phosphorus homeostasis. It is known to protect us from respiratory illnesses. Furthermore, vitamin D deficiency is a very common problem that contributes to the occurrence of various health conditions.
What is vitamin D?
Vitamin D3 [aka cholecalciferol] is an essential fat-soluble nutrient. Our bodies metabolize it in the skin from 7-dehydrocholesterol [provitamin D]. The synthesis of vitamin D3 requires UVB light [sunlight]. The liver and kidney convert vitamin D3 into its main circulating form, 25(OH)D, and its hormone form, 1,25(OH)2D. Vitamin D3 and its metabolites are considered steroid hormones[1]. Additionally, vitamin D can be obtained from food sources such as fish, fish oils, liver, and eggs.
Types of vitamin D
Vitamin D is a group of secosteroids. This group includes:
Vitamin D3 [cholecalciferol] is made in the skin and is also found in animal products.
Vitamin D2 [ergocalciferol] is found in plants, which makes it popular among vegans. People get it from their diet or by taking a supplement.
Vitamin D5 [sitocalciferol] is a synthetic vitamin D derivative developed in 1997 by Robert M. Moriarty and Dragos Albinescu that is used as an antitumor agent[2].
According to a meta-analysis conducted by Tripkovic, Lambert, and Hart[3], both forms of naturally occurring vitamin D can be used by the body, but to varying degrees of effectiveness. Although vitamin D2 and vitamin D3 have long been regarded as being equivalent, this research indicates that vitamin D3 may actually be much more efficient than vitamin D2. Vitamin D3 has a greater effect on increasing serum 25(OH)D concentrations.
Functions in the body
Vitamin D3 possesses the characteristics of a vitamin as well as a hormone. Its metabolite, 25(OH)D, is the most abundant form of this nutrient in the human body and is commonly measured with standardized blood tests. The liver produces it from cholecalciferol [vitamin D3].
Another metabolite of vitamin D3 is known as 1,25(OH)2D. It is a hormone that the kidney produces from 25(OH)D. It is also the most active form of vitamin D3 in the body, which is responsible for most of its effects. 1,25-dihydroxyvitamin D performs the following functions:
increases calcium absorption in the gut[4],
regulates calcium reabsorption in the kidney[4],
supports bone formation and skeletal system development[5],
inhibits parthyroid hormone secrestion[6],
stimulates insulin secretion[6],
regulates immune function[6],
stimulates the innate immune response - activates cathelicidin[7],
stimulates an adaptive immune response, activates T-cells, and inhibits pro-inflammatory cytokine production [IL-12, IL-23, and IL-6][7],
supports the treatment of psoriasis[8],
increases lipogenesis [the conversion of fatty acids and glycerol into fats] and decreases lipolysis [the conversion of lipid triglycerides into glycerol and free fatty acids][9],
can suppress tumor development[7],
suppresses markers of cardiac hypertrophy[7],
supports brain development and cognitive functions[10],
influences male and female fertility and reproductive health[15].
Deficiency symptoms
A deficiency in vitamin D has many repercussions for human health. Considering the number of functions it performs in our bodies, it is only logical to assume that some of the processes that require its presence will be disrupted. Low serum 25(OH)D levels have been linked to:
rickets[6],
increased risk of respiratory illnesses, including COVID-19[6],
increased risk of type 1 and type 2 diabetes mellitus[6],
hypocalcemia[6],
hypophosphatemia[6],
osteomalacia[7],
increased risk of fractures[8],
insulin resistance[8],
cardiomyopathy[11],
increased risk of cardiovascular disease[11],
accelerated age-related cognitive decline[12],
muscle weakness[13],
depression[14],
infertility[15].
Our health condition and preexisting health problems may be decisive in determining how well our body produces and/or metabolizes vitamin D. There are some people who may have difficulty maintaining an adequate level of serum 25(OH)D. Those are: the elderly, people with dark skin, people with conditions that impact fat absorption [Crohn's disease, celiac disease, ulcerative colitis], people who underwent gastric bypass surgery, and people who do not expose themselves enough to sunshine [cover their body and head the whole year round and use an excessive amount of sunscreen].
Synergism and antagonism with other nutrients
The relationship between various nutrients can either promote the proper functioning of our internal system or disturb it. The key to keeping our bodies healthy is an awareness of how much of each nutrient we need to maintain all our functions at an optimal level. What defines synergistic and antagonistic links between micronutrients are their functions and their amounts. One nutrient can have both positive and negative effects on another. The difference is in the ratio and, in the case of a supplement, the amount we take daily to support our health.
Vitamin D has a synergistic relationship with:
vitamin K - prevents vascular calcification and promotes the deposition of calcium into the bones[16]; supports heart health, and promotes proper blood clotting[17].
vitamin A - vitamins A and D help maintain a healthy gut[31].
Vitamins B2, B3, and B12 aid proper brain and cognitive function[18], growth and development[19], and protect the Central Nervous System[20].
vitamin E - boosts immune function[21], aids cognitive health[22], and prevents blood clotting[23].
magnesium - helps convert vitamin D into its active form, 1,25(OH)2D, which aids vitamin D transport in the blood[24].
copper: vitamin D increases copper cell availability[26].
manganese: vitamin D supports healthy gene expression that regulates manganese homostasis[27].
sodium: vitamin D helps maintain healthy sodium levels and proper blood pressure[28].
phosphorus: vitamin D aids phosphorus metabolism, which is essential for bone health and cell function[29].
Vitamin D can have an antagonistic relationship with:
The fact that the above vitamins and minerals work against each other is due to an imbalance in their amounts. When one element is present in excess, it affects the ability of the other to perform its functions. If they are in the right amounts in our bodies, they will work well together and support our health.
How much vitamin D do I need?
Vitamin D deficiency is a very common problem that may be decisive for our health and well-being. A blood test is required to establish the level of any micronutrient, including vitamin D, in our system. According to functional medicine[37], optimal levels of this micronutrient in our blood should range between 60 ng/mL [150 nmol/L] and 80 ng/mL [200 nmol/L]. A vitamin D serum concentration of 30 ng/mL [75 nmol/L] or less is considered deficient. Whereas, 10 ng/mL [25 nmol/L] or less indicates a severe deficiency. Depending on blood test results, a well-informed medical practitioner will be able to advise on how to maintain or raise the level of vitamins in your blood. Deficiencies usually require supplementation, and your doctor can make a proper recommendation regarding the dosing. It is also recommended to run a blood panel once a year to monitor any changes and potential micronutrient deficiencies and address them as soon as they are revealed.
Vitamin D supplements
There are a wide variety of supplements available on the market that we get to choose from. If it comes to vitamin D3 supplements, some of the most important things to remember are:
The best results come from a combination of vitamin D3 and vitamin K2. Unless you are told otherwise, choose supplements that contain both of these micronutrients.
Because vitamin D3 dissolves in fat, the ingredient list should include a good-quality [preferably organic] fat, like olive oil, MCT oil, or coconut oil.
Vitamin D3 supplements are sold in different forms, such as drops, soft gels, tablets, and sublingual solutions. Depending on your needs, choose one that offers the required dosage and is cost efficient.
Vitamin D3 is obtained from animal sources. Therefore, it might not be suitable for vegans. Talk to a knowledgeable practitioner about your options.
Choose a good quality supplement that comes from a manufacturer with proper safety and purity certifications.
Final Thoughts
Vitamin D3 is a key nutrient and a very important hormone. It helps build strong bones, boosts our immune system, protects us from autoimmune diseases like psoriasis, and helps keep our hearts, brains, and reproductive systems healthy. The right amount of this micronutrient helps insulin work well, fights inflammation, and keeps us from getting respiratory illnesses. Vitamin D is so essential to our health that our body is able to produce it on its own. Sun exposure is a catalyst that triggers the conversion of 7-dehydrocholesterol into 25(OH)D. However, our lifestyle choices may lead to an insufficient amount of sun exposure. This may cause a deficiency of vitamin D in our systems. Supplementation is a viable solution for people who are deficient in vitamin D.
Takeaway Points
Vitamin D is an essential nutrient that our body is able to synthesize in the skin.
1,25(OH)2D is a metabolite of vitamin D3 and its most active form.
Vitamin D3 deficiency is a common problem.
Vitamin D3 is more effective than vitamin D2 at increasing serum 25(OH)D levels.
Vitamin D3 has to be taken in a proper ratio with other micronutrients for maximum effect.
Optimal concentrations of vitamin D3 range between 60 ng/mL [150 nmol/L] and 80 ng/mL [200 nmol/L].
Regular blood tests help monitor the level of vitamin D in the blood stream.
Good quality supplements are an effective way of boosting vitamin D status.
References
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