Ultimate Guide to Vitamin D: How the Sunshine Vitamin Supports Your Alkaline Diet
The Importance of Vitamin D: Exploring the Science and Benefits of the Sunshine Vitamin
Vitamin D, often called the ‘sunshine vitamin,’ is critically important to our health but frequently overlooked or underestimated. Although its role in bone health has been widely recognized, this is just scratching the surface of its numerous health benefits.
Alarmingly, a significant number of people worldwide are deficient in this essential nutrient, with recent data suggesting up to 70% of the US population have deficient or insufficient levels (1). This deficiency can lead to a host of avoidable health issues. As you will know if you’ve been with me for any time, I am incredibly passionate about preventing preventable sickness and disease*, and adequate vitamin D is a simple, cheap and powerful way to support this.
As a key component of the alkaline diet, which emphasizes nutrient-rich, plant-based foods, understanding vitamin D’s role in our health is vital. In this guide, we will cover everything you need to know about vitamin D, including:
- What vitamin D actually is, and what it does
- What the benefits of adequate vitamin D levels are, and the risks of vitamin D deficiency
- The different ‘types’ of vitamin D
- How much vitamin D do you need, and what is ‘too much’?
- The nutrients and important factors in vitamin D metabolism and usage
- The SUN and vitamin D (and staying safe)
- How to test your vitamin D status
- Food sources of vitamin D
- And the low-down on supplements, and recommendations.
We will explore the importance of vitamin D, its functions in the body, and the factors that influence its levels. We will also discuss the roles of magnesium and vitamin K in vitamin D metabolism, as well as testing and monitoring options to ensure optimal vitamin D status. Finally, we will provide guidelines for balancing sun exposure and supplementation to achieve and maintain healthy vitamin D levels for better overall health.
Sound good? Let’s get into it!
What is vitamin D, and what does it do?
Surprisingly to many, vitamin D is actually a hormone. Unlike many other trace nutrients that have to be consumed through our diet, vitamin D is produced within the body when a molecule in our skin reacts to ultraviolet B light.
The process has many complex names, enzymes, and stages, but most simply:
- Step One: ultraviolet B light hits the skin’s epidermal layer, this reaction creates precursor vitamin D,
- Step Two: this is then converted into vitamin D (cholecalciferol).
- Step Three: the cholecalciferol is then transported in the blood to your liver to form calcidiol, the main circulating form of D3.
- Step Four: the calcidiol then travels to the kidneys where it forms the active steroid hormone, also known as calcitriol
There are lots of enzymes, hormones, glands and other nutrients involved in this process, alongside the blood, liver, and kidneys. If you’ve read my first book The Alkaline Reset Cleanse, you’ll know all about the interconnectedness of our ‘Five Master Systems’ of the endocrine system, immune system, detoxification system (liver, kidneys, lymph), digestive system and pH buffering system.
I talk a lot about how these systems are reliant on one another, and the myriad ways that a challenge with one can lead to multiple imbalances in the others, and this is another great example. If the liver and kidneys are not functioning properly, this will impact vitamin D synthesis, which then has a huge flow on effect to the immune system (see more below).
Similarly, the parathyroid glands also play a huge role in vitamin D production, and so an imbalance in your endocrine system can have a similar flow-on effect.
Certain digestive imbalances, such as Crohn’s disease, celiac disease, and cystic fibrosis, can also impair the body’s ability to absorb fat-soluble vitamins like vitamin D, leading to deficiency.
So you can see here the digestive, immune, detoxification, and endocrine systems are all related to vitamin D processing, synthesis, storage, and usability, and the huge implications of the deficiency this causes.
What else plays a role in vitamin D synthesis?
There are several other nutrients that are essential in maintaining healthy vitamin D levels. Alongside those nutrients required for healthy liver and kidney function, and a well-balanced endocrine system, there are also six vitally important enzymes, several of which are magnesium dependent. There are many studies showing how magnesium deficiency is linked to vitamin D status, and this is arguably the reason why (2, 3).
The Role of Vitamin D in our Health
Vitamin D plays a variety of critical roles in the body, contributing to several essential functions and processes:
- Bone health: Vitamin D helps maintain calcium and phosphorus balance in the body, which is crucial for bone health. It increases calcium absorption from the intestines and regulates the balance of calcium and phosphorus in the blood, promoting bone mineralization and preventing conditions like rickets in children and osteomalacia or osteoporosis in adults.
- Immune function: Vitamin D supports the immune system by modulating both innate and adaptive immune responses. It helps regulate the function of immune cells, such as T cells, B cells, and macrophages, and has anti-inflammatory properties, contributing to the body’s defense against infections and autoimmune diseases.
- Cell growth and differentiation: Vitamin D plays a role in regulating cell growth and differentiation, influencing the life cycle of cells, including cell proliferation, apoptosis (programmed cell death), and differentiation into specialized cell types. This function is important in maintaining healthy tissues and preventing abnormal cell growth, such as cancer.
- Neuromuscular function: Vitamin D is essential for the proper functioning of the nervous system and muscles. It helps maintain nerve conduction, muscle contraction, and overall coordination, reducing the risk of falls and fractures in older adults.
- Cardiovascular health: Emerging evidence suggests that vitamin D may play a role in cardiovascular health by regulating blood pressure, reducing inflammation, and protecting against atherosclerosis and other cardiovascular diseases.
However, it is important to note that a DEFICIENCY in vitamin D is implicated in a huge range of health complications and increased risk of many preventable conditions.
The risks of vitamin D deficiency
As mentioned, up to 70% of the US population (and it is similar in other countries) are deficient or insufficient in vitamin D. There are greater risks for certain populations, such as dark-skinned people, as those of African or Hispanic descent, those who are obese, smoke, or have diabetes (4).
The ease of fixing this deficiency, which we will get to shortly, is good news, because the risks arising from deficiency are many.
Why are so many people deficient?
There is some controversy around this topic, and there are a few factors at play that are contributing to the low levels of vitamin D at a population level.
Firstly, we are now so much more scared of any sun exposure. It is not to underestimate the risk of skin cancer, but many studies are suggesting we have now gone too far with our appetite for sun on our skin. At a population level, we are also now spending so much more time indoors, not giving our skin access to the ultraviolet B rays that begin the vitamin D process.
There has also been many experts arguing for many years that the Recommended Daily Intake (RDI) of vitamin D is woefully low. This RDI was first set in the 1940’s and is just 800iu per day. The recommendation at the time was based upon the understanding of vitamin D simply for bone health.
Research since the 1940s has shown how vital vitamin D is, indicating that vitamin D status influences risk for many chronic diseases, such as metabolic syndrome, cardiovascular disease, autoimmune disorders, cancer, and many other causes of premature death. Studies now suggest that the RDI should be somewhere between 1,500-4,000iu per day (5). This lack of importance on getting enough vitamin D has led to many people dropping too low.
There are other population-level reasons why vitamin D status is so low. The rise in obesity levels has definitely not helped. This study from 2023 shows how excess body fat impairs the storage and release of vitamin D from within the fat tissue. The digestive disorders mentioned earlier are far more prevalent now than at any other time, plus with an aging population, we know that as we age the skin loses its ability to synthesize vitamin D.
However, we can address all of these issues, and even in spite of them, still achieve and maintain sufficient vitamin D levels in the body.
Vitamin D deficiency must be addressed, as it can lead to:
- Osteomalacia: A condition in adults that causes softening of the bones due to inadequate mineralization, resulting in bone pain, muscle weakness, and an increased risk of fractures.
- Osteoporosis: A progressive bone disorder characterized by decreased bone density and increased risk of fractures, especially in older adults. Vitamin D deficiency contributes to the development of osteoporosis by affecting calcium absorption and bone metabolism.
- Autoimmune diseases: Vitamin D deficiency has been associated with an increased risk of developing autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and type 1 diabetes, due to its role in modulating immune function.
- Cardiovascular diseases: Low levels of vitamin D have been linked to a higher risk of hypertension, heart failure, and coronary artery disease, as vitamin D plays a role in regulating blood pressure and inflammation.
- Cancer: Vitamin D deficiency may be associated with an increased risk of certain types of cancer, including breast, prostate, and colon cancer. Vitamin D plays a role in regulating cell growth and differentiation, which can influence cancer development and progression.
- Mental health disorders: Insufficient vitamin D levels have been associated with an increased risk of depression and cognitive decline, especially in older adults.
- Infections: Vitamin D deficiency can impair the immune system’s ability to fight off infections, increasing the risk of respiratory infections such as pneumonia and tuberculosis.
- Diabetes: Low vitamin D levels have been linked to an increased risk of type 2 diabetes, as vitamin D may influence insulin sensitivity and pancreatic beta-cell function.
Plus the inability to perform those roles discussed earlier: bone health, immune function, cell growth, cardiovascular health and neuromuscular function.
It’s all a little bit more than just bone health!
The Different ‘Types’ of Vitamin D
This is worth briefly touching upon as it does cause some confusion.
There are two forms of vitamin D:
- Vitamin D2 (ergocalciferol): Vitamin D2 is produced by fungi and plants, particularly in response to UVB radiation. It can be found in some mushrooms exposed to sunlight or UV light, as well as in fortified foods and supplements. Although vitamin D2 can be used to prevent and treat vitamin D deficiency, it is generally considered less effective than vitamin D3 in raising and maintaining blood levels of the active form of the vitamin.
- Vitamin D3 (cholecalciferol): Vitamin D3 is synthesized in the skin of humans and animals upon exposure to UVB radiation from sunlight. It can also be found in certain animal-derived foods, such as fatty fish, fish liver oil, egg yolks, and liver. Vitamin D3 is often used in supplements and fortified foods because it is more effective at raising and maintaining blood levels of the active form of vitamin D, compared to vitamin D2.
D2 is very rarely used exogenously (in vitamins/supplements/medications), only sometimes with prescription products. D3 is by far the more common form used in supplementation. Both forms are biologically inactive and have to go through the stages described at the beginning of this guide, so it is important to note that supplementation is not always the answer, alone. The other factors have to be in place too such as adequate magnesium intake, liver, kidney, and parathyroid health, healthy blood cells, and not too much excess body fat.
It’s not to say we can’t achieve optimal D3 levels if any of these factors are also present, but each makes it a little more difficult.
How much vitamin D you need, and what is ‘too much’?
As mentioned there is some disagreement and controversy to this. Many studies show that the current levels deemed ‘sufficient’ are too low, and that the RDI is also too low. Personally, I aim to be a fair amount above the Government recommended ‘sufficient’ level.
As of 2011 the Institute of Medicine, or IOM, published:
- serum 25(OH)D concentrations less than 30 nmol/L (less than 12 ng/mL) places people “at risk of vitamin D deficiency”;
- 30 to 50 nmol/L (12 to 20 ng/mL) places some populations “at risk for inadequacy”;
- and concentrations of 50 nmol/L (20 ng/mL) or greater are considered “sufficient.”
Based on these levels, they also suggest that the RDI of 800iu is enough. I personally disagree, as do several studies.
An analysis of 2,700 people showed that consuming 1,000 to 2,000 IU of vitamin D twice a week for one month did not increase serum levels. However, 2,000 to 3,000 IU elicited a 7 percent increase; 3,000 to 4,000 IU elicited a 13 percent increase; and 5,000 IU elicited a 30 percent increase.
Remember, this is 5,000iu, but only twice a week.
Taking the supplement 3-6 times per week increased serum levels a little more, but seven times per week (daily) of 5,000iu finally got serum levels up 30nmol (6).
This is where it practically tapers off. More vitamin D, and for a long duration did not seem to increase serum levels in a linear manner, it basically became maintenance at this point.
But can you overdose?
It is incredibly rare. Firstly, when the body has enough vitamin D stored it stops processing it from the skin/sun exposure. It literally just turns that mechanism off.
From supplementation, a Mayo Clinic study on over 20,000 participants taking high-dose vitamin D showed only ONE single case of toxicity, and this was in a subject taking 50,000iu daily for three months, alongside a high-dose calcium supplement (you can read more here).
Taking between 1,000-5,000iu daily is not going to cause any harmful effects.
The SUN and vitamin D (and staying safe)
There is a balance to getting enough vitamin D from the sun, whilst staying aware of not over-exposing yourself and increasing skin cancer risk. My personal belief is that we have become too scared of the sun and now cover ourselves too much, and for too long. We do not want to expose ourselves to sunburn, of course, but having vitamin D deficiency is also a strong cancer risk.
The general recommendation is to get between 10-20 minutes of sun exposure to at least 25% of your skin, as close to noon as possible.
Occasional exposure of your hands and face will not cut it. Remember, overexposure to the sun can result in sunburn, which will increase your risk for skin cancer and premature skin aging.
Again, after you get the necessary amount of sunlight, your body will switch off vitamin D production.
The best time to expose yourself to the sun is as near to solar noon as possible. You need UVB rays, not UVA rays (that are present all throughout the day) and UVB is very low in the morning and evening. Don’t overthink it but anything around 10:00 am to 2:00 pm is great.
It’s also important to note that fair-skinned people can potentially get enough sunlight in just 10 to 20 minutes. However, if you have darker skin, you likely need to remain in the sun longer due to the melanin in the skin pigment, which competes for UVB.
The skin around your eyes is super thin and sensitive compared to other areas on your body, and prone to sun burn and premature aging. It is not going to contribute a great deal to your vitamin D levels, so do feel free to cover your face with a hat or natural sunscreen.
How to test your vitamin D status
To keep this really simple, I believe it’s better to be safe than sorry, and simply add a D3 supplement to your daily routine. Supplement between 1,000iu and 5,000iu, each day. I like to mix it up and keep it a bit random to keep my body guessing (ha!), and you can even have days off here and there too. It’s good with all supplements to mix it up a bit.
But the point is, if you are now supplementing properly with D3, and looking after your wider health by living an alkaline life, then where your D3 status is now is practically irrelevant. If it is low, then you will supplement to raise it. If it is adequate you will also want to supplement to maintain it. So regardless, you will be supplementing.
However, if you do want to test, here are the two main options:
25-hydroxyvitamin D (25(OH)D) blood test:
- Measures the level of calcidiol (25(OH)D) in the blood
- Considered the most accurate and reliable method for assessing vitamin D status
- Reflects vitamin D obtained from sunlight exposure, diet, and supplements
1,25-dihydroxyvitamin D (1,25(OH)2D) blood test:
- Measures the level of calcitriol (1,25(OH)2D), the active form of vitamin D in the body
- Not commonly used to assess overall vitamin D status, as it is typically within the normal range even when a person is deficient in 25(OH)D
- Mainly used to help diagnose specific medical conditions, such as kidney disorders or issues with parathyroid gland function
It’s important to note that there can be huge variations and errors in these tests so they are not always going to be 100% fully accurate. However, they can be a good measure to track over time, as any anomalies will be picked up if you test several times over a longer time period.
Food sources of vitamin D
Aside from the sun, and supplements, there are a few food sources of vitamin D, however, few of these are alkaline forming.
- Oily fish, including halibut, mackerel, wild-caught salmon, whitefish, rainbow trout, sardines, tuna
- Pastured eggs
- Beef liver
- Raw milk
- Fortified milk and fortified milk alternatives, such as nut-based milks
- Maitake and portobello mushrooms (when they have been exposed to UV light)
And the low-down on supplements, and recommendations.
As some of you know, I was a supplement business long, long before I was coaching living alkaline, and I can tell you from experience that vitamin D is a very easy supplement to manufacture. There is very little quality difference with any of the trusted brands that I recommend below.
There may be times that you want to increase your daily dosage to around 10,000iu if you’re feeling a cold or flu coming, or under the guidance of your physician, but I do not recommend purchasing a product that has a 10,000iu per capsule dose, as these times will be fairly rare.
Instead, I recommend getting two products. One that is either 1,000iu or 2,000iu and one that is 5,000iu. Vitamin D3 is relatively cheap, so this won’t break the bank.
Here are my recommendations:
- Nordic Naturals 1,000iu (very high quality)
- Nordic Naturals 5,000iu
- Thorne Research Liquid D3 – if you prefer liquid, Thorne are FANTASTIC
- Life Extension 1,000iu (decent quality, a bit cheaper)
- Life Extension 5,000iu
These will certainly all do a great job!
Recent Research into Vitamin D
Vitamin D is perhaps one of the most researched nutrients, and it is not without reason. The evidence continues to mount as to the importance of this vitamin, and the nuances around vitamin D synthesis, individual requirements, and the wide-ranging benefits continue to be of considerable interest.
Here’s just a handful of research published in the past 6-12 months at the time of writing:
- The Role of Vitamin D and Periodontal Disease (December, 2022) – “clinical studies have consistently demonstrated an inverse relationship between serum 25OHD3 (vitamin D levels) and periodontal disease inflammation”.
What is the impact of daily oral supplementation of vitamin D3 (cholecalciferol) plus calcium on the incidence of hip fracture in older people? A systematic review and meta-analysis (July, 2022) – increased vitamin D status linked to decreased risk of hip fracture.
Effects of long-term vitamin D supplementation on metabolic profile in middle-aged and elderly patients with type 2 diabetes (January, 2023) – low vitamin D increases risk of metabolic disease, exacerbated by type 2 diabetes.
- Vitamin D deficiency and C-reactive protein: a bidirectional Mendelian randomization study (May, 2022) – Low vitamin D status linked to chronic inflammation.
This is an Easy Win – Start Now!
Maintaining optimal vitamin D levels is essential for overall health and well-being. The numerous roles vitamin D plays in the body, from supporting bone health to regulating immune function and maintaining cardiovascular health, make it a vital nutrient for everyone. Despite its importance, a significant number of people worldwide are deficient in this essential nutrient, primarily due to limited sun exposure, inadequate dietary intake, and other factors.
Understanding the different forms of vitamin D, as well as the factors that influence its levels, is crucial for maintaining optimal health. Additionally, the roles of magnesium and vitamin K in vitamin D metabolism and utilization should not be overlooked, as these nutrients work synergistically to support various physiological processes.
To ensure adequate vitamin D levels, it is essential to balance sun exposure, and consider supplementation if necessary, especially for those with limited sun exposure or other risk factors.
Incorporating vitamin D into an alkaline diet plan can further promote overall health by emphasizing the consumption of nutrient-rich, plant-based foods. By understanding the importance of vitamin D, as well as its various sources, forms, and functions in the body, individuals can make informed decisions about their nutritional needs and lead a healthier, more vibrant life.
Get started now, let’s do this,
*Note: many, many of the most common diseases are preventable through diet and lifestyle choices, according to research collected by the Centers for Disease Control, Harvard University and the Alzheimer’s Association, to name a few:
· Cancer: Between up to 95% preventable through diet[i]
· Type 2 diabetes: 90% preventable through diet[ii]
· Heart Disease: 82% preventable through diet[iii]
· Stroke: 80% preventable at least through diet[iv]
· Alzheimer’s: up to 99% preventable through diet[v]
Your health and your future are in your hands.
References & Further Reading
- Parva, Naveen R; Tadepalli, Satish; Qian, Andrew; Joshi, Rajat; Kandala, Hyndavi; Nookala, Vinod K, et al. (2018). Prevalence Of Vitamin D Deficiency And Associated Risk Factors In The US Population (2011-2012) Cureus , .
- Razzaque, M. Shawkat; Uwitonze, Anne Marie (2018). Role Of Magnesium In Vitamin D Activation And Function The Journal Of The American Osteopathic Association 118, 3.
- Ryzen, Elisabeth; Endres, David B.; Niimi, Hiroo; Horst, Ronald L.; Haddad, John G.; Singer, Frederick R., et al. (1985). Low Serum Concentrations Of 1,25-Dihydroxyvitamin D In Human Magnesium Deficiency The Journal Of Clinical Endocrinology & Metabolism 61, 5.
- Parva, Naveen R; Tadepalli, Satish; Qian, Andrew; Joshi, Rajat; Kandala, Hyndavi; Nookala, Vinod K, et al. (2018). Prevalence Of Vitamin D Deficiency And Associated Risk Factors In The US Population (2011-2012) Cureus , .
- Tebben, Peter J.; Singh, Ravinder J.; Kumar, Rajiv (2016). Vitamin D-Mediated Hypercalcemia: Mechanisms, Diagnosis, And Treatment Endocrine Reviews 37,
- Chao, Yi-Sheng; Brunel, Ludovic; Faris, Peter; Veugelers, Pj (2013). The Importance Of Dose, Frequency And Duration Of Vitamin D Supplementation For Plasma 25-Hydroxyvitamin D Nutrients 5, 10.
hi: I greatly appreciate all of your information; as a nutritionist, i do know much of it; but, it’s always good to be reminded of how much I don’t remember.. As a vegan, however, I do supplement with liquid D3, Solgar, 5,000 IU daily. I was also diagnosed with osteoporosis & I have had many back problems. Several years ago, my doctor recommended either an injection or a prescription. I researched & found the supplement on my own. I also purchased an alkaline food plan book (sorry, it’s not yours). I look forward to more information. Thanks so much.
So good to hear and I hope you’re on the right track with your back now. I had an L5/S1 disc issue a year or so ago and was told over and over surgery surgery surgery. I absolutely did not and used specific focus with my diet and am absolutely great again now. BUT it was not pleasant along the way, so I hope your back got better!
Not to plug my own book, but also to absolutely plug it at the same time…I really do highly recommend it 🙂
You can grab it on amazon here: https://smarturl.it/amz-arc
There are so many studies supporting the alkaline life for osteoporosis, I think you’ll do really well with it, and my book will get you on the right track 🙂
What a very extensive and thorough article about Vitamin D3 and D2 .
Much I already knew, but so much more information! Like your book on the Alkaline Reset Cleanse, you explain everything so thoroughly, that one really understands the importance of the subject.
Thank you very much for this article Ross!
Thank you so much Anneliese!