Vitamin D, otherwise known as calciferol, is an essential fat-soluble micronutrient that works as a hormone to support and regulate many vital functions and processes.
Low vitamin D intake is considered a significant public health concern, with 13% of the world’s population estimated to be deficient. Someone is particularly prone to low vitamin D levels if they live far from the equator or spend little time outdoors.
- Roles of Vitamin D in the Body
- Vitamin D Rich Food Sources
- Vitamin D Boosting Recipes
- Symptoms of Vitamin D Deficiency
- How Much Vitamin D Do You Need?
- Vitamin D Toxicity and Overdose
- Optimal Calcium: Phosphorus Ratio
- Can I Get Enough Vitamin D from Food Alone?
- Synergistic Nutrients with Vitamin D
- Processing Losses
- How Do I Calculate My Vitamin D Intake From Food?
Roles of Vitamin D in the Body
Adequate vitamin D is critical to maintaining strong bones because it facilitates the absorption of both calcium and phosphorus in the GI tract. Vitamin D also:
- works with vitamin A to boost your immune system,
- helps prevent asthma and allergies,
- plays a role in bone reabsorption and remodelling,
- regulates cell growth,
- aides in glucose metabolism,
- helps prevent type 1 diabetes,
- reduces inflammation,
- controls infection,
- normalises mood,
- boosts cognition,
- regulates immune cell activity,
- helps to lower blood pressure,
- helps to boost testosterone in men,
- helps to avoid excess male hormones in women, and
- reduces the risk of certain cancers in the gut and reproductive organs.
Vitamin D in its cholecalciferol form is synthesised when UVB rays from sunlight react with cholesterol in the skin. From here, the liver and kidneys work together to convert it to its bioactive form.
While supplementation may be necessary for someone living far from the equator, adequate sun exposure is ideal for maintaining healthy vitamin D levels in the blood.
Similarly, someone who spends a lot of time indoors from their job or school may also make less vitamin D. Low vitamin D levels are associated with skin cancer. While it may seem counterintuitive, this nutrient level is also reduced when it is recommended to limit sun exposure.
At the other extreme, excessive vitamin D supplementation can cause the body to absorb too much calcium. As a result, it can end up in places it doesn’t belong, like your arteries, contributing to heart disease.
A nutrient-dense diet will contain a significant amount of vitamin D2 and D3, but it is far from enough to meet your minimum requirement. This is especially true if you suffer from a condition that increases your body’s demand. Some popular foods that contain more vitamin D are listed below.
- cod liver oil
- milk (fortified)
- chicken breast
- black pepper
Rather than micromanaging your dietary vitamin D, we highly recommend going for a walk with your dog, friend, or loved one in the morning or afternoon sun!
Vitamin D Boosting Recipes
Some examples of our NutriBooster recipes rich in Vitamin D include:
- broccoslaw with salmon
- blackened fish stir fry (pictured below)
- slaw & wild salmon
- pan-fried fish, olive & tomato salad
Symptoms of Vitamin D Deficiency
Lower intakes of vitamin D are associated with:
- low calcium levels,
- loss of appetite,
- immune disorders like cancer or autoimmunity,
- low immunity,
- histamine intolerance,
- joint pain,
- impaired wound healing,
- hair loss,
- thyroid disorders,
- stunted growth, and
- softening of the bones and teeth.
It’s important to consider that insufficient intake also affects the body’s phosphorus and calcium levels.
The Adequate Intake level of vitamin D of 10 micrograms per day for adults less than 50 years old is based on the amount of dietary vitamin D required to maintain healthy blood levels of this nutrient without significant sunlight exposure.
However, it is tough to construct a nutrient-dense diet that meets the Adequate Intake of vitamin D from food alone. Vitamin D supplements are typically not as effective as dietary intake or sun exposure, potentially because vitamin D is so tightly related to calcium and phosphorus intake. Vitamin D supplementation also requires sulphation, which can be compromised in some people.
The Upper Limit for vitamin D is set at 80 micrograms (4,000 IU) per day for adults and 25 micrograms (1,000 IU) per day in infants due to the danger of excess calcium absorption (hypercalcemia). So the best way to determine the correct vitamin D dose for you is to monitor your blood tests and titrate your supplementation, food, and sun exposure accordingly.
Vitamin D toxicity is known as hypervitaminosis D. This condition does not result from sun exposure but from consuming excessive amounts of vitamin D supplements. Hypercalcemia has been observed in people supplementing high doses of vitamin D in doses exceeding 50,000 IU per day.
Vitamin D toxicity is unlikely in healthy people if consumption is less than 10,000 IU/day. However, the official Upper Limit for Vitamin D has been set at 4,000 IU per day.
Because vitamin D is fat-soluble, it takes longer for the body to metabolise and excrete. Supplementing less than 10,000 IU/day can still result in toxicity for someone with a compromised liver. For this reason, it’s best to monitor your levels closely if supplementing.
You can’t just take Vitamin D in isolation and expect it to work optimally. For vitamin D to do its job correctly, you must ensure you’re also getting enough calcium and phosphorus.
Can I Get Enough Vitamin D from Food Alone?
While foods can provide small amounts of vitamin D, it’s not enough to be considered sufficient. The bottom line is that it’s good to get out and get some sun on your skin regularly while making sure you don’t burn.
You can use the D Minder app to determine how much sun you need based on your location, time of day, amount of clothes you are wearing, and skin colour.
Adequate sun exposure is also critical to good sleep and setting your circadian rhythm in an environment where many spend their days and nights under artificial light looking at screens.
Vitamin D2 (ergocalciferol) is made by plants, while animals synthesise D3. Vitamin D3 is considered the more active and bioavailable form of vitamin D. Foods containing D3 are animal foods, whereas foods containing D2 are from plants.
If you’re eating vitamin D containing foods, getting sunlight, and supplementing regularly, then either form is acceptable. This will ensure you’re getting some form of the more active D3. However, if you are not supplementing regularly, D3 is better because it stays in circulation for longer and is more bioactive.
Vitamin D works synergistically with vitamins A, B3, K, boron, calcium, copper, magnesium, manganese, phosphorus, sodium, and calcium. This means vitamin D requires all of these nutrients to do its job. For this reason, we recommend getting vitamin D3 from sunlight and consuming nutrient-dense foods to ensure you’re getting enough of other necessary vitamins and minerals.
Given that vitamin D is synthesised from sunlight, it’s ironic that vitamin D in food is unstable in the presence of light. It is also relatively unstable when exposed to more acidic conditions. Vitamin D is moderately heat stable, with around 39-45% retained during the cooking process.
If you’re interested in checking if you’re getting enough vitamin D, you can check your nutrient profile using our Free 7-Day Nutrient Clarity Challenge.
Level Up Your Nutrient Density
To help you level up your nutrient density, we’ve prepared a Nutritional Optimisation Starter Pack to ensure you are getting plenty of all the essential nutrients from the food you eat every day.
The free starter pack includes:
- Maximum Nutrient Density Food List
- Sample Maximum Nutrient Density Recipe Book
- Sample Maximum Nutrient Density Meal Plan.
To get started today, all you have to do is join our new Optimising Nutrition Group here.
Once you join, you will find the Nutritional Optimisation starter pack in the discovery section here.
Nutrient Density Index
- Vitamin A
- Vitamin E
- Thiamine (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic acid (B5)
- Vitamin B6
- Folate (B9)
- Vitamin B12
- Vitamin C
- Vitamin D
- Vitamin K1