Getting the right amount of vitamin D
The main sources of vitamin D come from exposure to sunshine, from our food or from supplementation. Around 90% (though depending on various factors, this can vary from 50–90%) of our required dose comes from exposing the skin to ultraviolet light, while the remaining 10% come from food and supplementation. But although vitamin D is known as the sunshine vitamin, it’s easier than you might think to go short on this vital nutrient.
This applies particularly to people living in the UK (or residing elsewhere within the Northern latitude), where months of dark wintry skies leave us all vulnerable. On top of this, there are a number of other reasons you might find yourself running low: • wearing sunscreen
• darker skin pigmentation
• if you’re aged over 65
• covering your skin, e.g., for religious or other reasons
• limited exposure to sunlight
• multiple short interval pregnancies
• inadequate public education on the necessity of vitamin D
New government guidelines recommend supplementation of this vitamin. We need to ensure we’re getting a daily dose of 10 mcg (a little less for babies under the age of one ––around 8.5 mcg). Between April and September getting out into the sunshine for around 15 to 20 minutes every day can help ensure we’re getting enough, though, for the reasons given in the list above, the 10-mcg target cannot be guaranteed year-round. Luckily this vitamin can be found in a number of food sources, and in light of its precarity and its necessity to health, a number of common foods are also now to be found fortified with this essential nutrient.
What is vitamin D?
Vitamin D is fat-soluble and actually comprises a family of nutrients with similarities in chemical structure. Of these, vitamin D2 (ergocalciferol) and D3 (cholecalciferol) are the most important forms. Although scientists used to think both were equally useful, we know now that D3 is the most important for our health and well-being. It is D3 that is most easily utilised by the body. In the human body, vitamin D3 is transported to the liver and then the kidneys for turn further conversions into 1,25–dihydroxy vitamin D, a pro-sterol hormone ––the bioactive form of vitamin D, also known as calcitriol.
Throughout the winter, higher levels of this variety are found to be more consistently present in the blood. It is vitamin D3 that is made in the body when we’re exposed to ultraviolet light. Otherwise, vitamin D3 is available from animal-based food sources, while D2 comes from plants and fortified foods. If you’re vegan, you’ll need to be aware of this distinction ––since fortified foods can contain either and D2 is cheaper of the two to make, you’ll need to ensure you’re getting the right kind. Vitamin D is essential for the absorption of calcium and phosphorus. Our bodies use it for building strong bones, keeping muscles strong, preventing gum disease, brain function, keeping our heart healthy and supporting our immune systems.
Foods with vitamin D3
Natural sources of vitamin D3 are:
• Oily fish –sardines, salmon, herring, halibut and mackerel
• Red meat, particularly liver
• Eggs, particularly egg yolk
• Milk Fortified sources, many of which are also vegan friendly, are:
• fish and algae oil supplements
• fortified dairy products
• fortified plant-based milk
• fortified cereals
• sun irradiated mushrooms
• vegan-friendly fungus called lichen
• some orange juices
An example menu for optimising your daily vitamin D intake might be: Breakfast: Whole eggs, scrambled egg paired with oily fish such as mackerel or smoked salmon or a fortified cereal such as oats with fortified plant milk. Pair these with D3 fortified orange juice. Lunch: How about a frittata (if you had cereal at breakfast-time) or a jacket potato topped with tuna. Dinner: Try an oily fish such as salmon paired with mushrooms grown in UV light.
Vitamin D deficiency
Becoming deficient in vitamin D is no fun and can result in a number of health issues, including bone and joint weaknesses that can lead to disorders such as rickets, osteomalacia (soft bones) or osteoporosis (brittle bones), carrying the risk of deformity and fractures; growth problems; gum disease; risk of infection and constipation. People eating plant-based diets may be at higher risk of deficiency, depending on how plant-based their diet is.
In the case of pescatarians or ovo-Lacto vegetarians, who include fish and/or dairy products in their diet, vitamin D intakes could easily be higher than those of the general population.
But for exclusive plant-based eaters ––or for those that simply don't enjoy these foods ––intakes from food will always be lower than is the case for omnivores. If you believe you need some additional support, either for these reasons or those given above, it makes sense to consider a quality daily Vitamin D3 supplement easily absorbed and digested by the body. If you do take a supplement, vitamin D3 is probably your best choice. Vitamin D3 supplements are more potent than vitamin D2 ––the precursor of D3.