Table of contents
Why is Vitamin D important
The importance of Vitamin D to the body cannot be overestimated. Also known as the ‘sunshine vitamin’, Vitamin D regulates the blood levels of calcium, magnesium and phosphate, which are all very important body minerals. This vitamin also keeps our skeletal systems strong and healthy and at the same time fortifies our immune systems making us less susceptible to diseases. Maintaining a healthy blood level of Vitamin D has been proved to lower the risk of common diseases like diabetes, HIV, influenza, tuberculosis, Alzheimer’s disease, dementia, Parkinson’s disease, heart disease, stroke and cancer. An on-going research has even linked healthy blood Vitamin D levels and lower mortality risks in older adults. 1
We get our Vitamin D supply from three major sources; the sun, food and supplements 2. Due to the dangers associated with sun exposure (sunburns, skin cancer) and the relatively small amounts of the Vitamin in food, supplementation is the preferred option for several people. However, just before you descend on your local pharmacy and become a Vitamin D supplement junkie, it is important to note that taking too much of the Vitamin could be very harmful to your body. Excessive use could lead to diverse problems such as hypercalcaemia, nausea, insomnia, disorientation, coma, cardiac arrest and in extreme cases; the kidneys and liver could be permanently damaged. 3 1
Vitamin D Daily Value Calculator
So just how much Vitamin D should you be taking? Is 5000 IU (International Unit) / day of the Vitamin D too low, just perfect or excessive for you? With our calculator we unveil a fool proof method to determine your body’s needed Vitamin D levels.
However to understand the process better let’s check how sunlight interacts with our skin to produce Vitamin D and the related determining factors.
Sunlight & Skin
Skin Type & Exposure Time to Sunlight
As mentioned above, sunlight is one of the major sources of Vitamin D. Our skins contain a particular form of cholesterol which reacts with the ultraviolet rays of the sun to produce the vitamin and the newly produced vitamin is then transported to various zones around the body where it is utilized. This reaction is hindered by sunscreen, clothing and glass boundaries as the UV rays involved are unable to penetrate these to interact with the skin.
The amount of Vitamin D that can be produced from the sun varies by person due to two major factors which are exposure time and skin type 2. Exposure time refers to the amount of time a person is in direct sun-skin contact. In our generation, this measurement is quite low compared to our predecessors, with the major culprits being our modern work environment and job demands. Skin type, on the other hand, talks about the disparity in Vitamin D produced from the sun due to the varying melanin concentration in human skins. Melanin is a form of natural defence to the sun ultra violet’s rays which are harmful to the skin in excessive quantities. Thus, the higher the melanin content, the more the time required to produce similar levels of Vitamin D as the rays have to work harder to break down the melanin layer. 3
The recommended 4 daily exposure times based on skin type are;
|Skin Type||Exposure Time (min)|
|Caucasian (light skinned)||10|
|African (dark skinned)||60|
Exceeding these durations in the sun could lead to sunburns which could damage the skin leading to unwanted skin problems most notable skin cancer. 5
Geographical positioning also affects the quantity of Vitamin D you are able to produce from sunlight. The specific ultraviolet rays which react with the skin to produce Vitamin D are called the Ultra Violet B rays and these rays are considerably weaker in areas of higher latitudes. What this means is that people who live closer to the equator tend to have higher levels of Vitamin D than those who live close to the poles. 6 7
Skin Surface Area in contact with Sunlight
The surface area of skin exposed to the sun also determines how much Vitamin D your skin is able to produce. As earlier stated, clothes, sunscreen or any form of shade preventing pure sun-skin contact won’t result in Vitamin D production.
The more skin you are able to expose at once, the faster and easier it is for the skin to produce the vitamin. The table below serves as a specific guide;
|S/N||Body parts in sun-skin contact||Probable dressing||Skin %|
|1||Arms and hands||T-Shirts, pants and hat||11|
|2||Face, neck, arms and hands||T-Shirts and pants||18|
|3||Face, neck, arms, hands, lower legs||Shirts and shorts||32|
|4||Top part of body||Stripped to waist||53|
|5||Sun on entire body||Bathing costume||73|
|6||Sun on entire body||Swimming costume||88|
Basic Vitamin D Needs
Now, let’s determine how much Vitamin D we really need. There is a simple formula for calculating your basic daily Vitamin D requirement and it is dependent on your body mass. The formula is;
“Basic daily Vitamin D (IU) = Body mass (lbs.) * 27” 8
The fixed rate of 27 IU per pound is the average amount of the vitamin needed to retain optimum blood levels (50 ng/ml), with input from sunlight not taken into account. According to the Centres for Disease Control and Prevention (CDC), the average weights of an American woman and man respectively are 166.2 and 195.7 pounds respectively while the average weight of the Europeans is pegged at 156.1 pounds.
Thus, applying our formula;
|Average Weight (lbs.)||Calculation||Basic daily Vitamin D (IU)|
|American Female||166.2||166.2 X 27||4487.4|
|American Male||195.7||195.7 X 27||5283.9|
|European Female/Male||156.1||156.1 X 27||4214.7|
Therefore, the daily Vitamin D requirements (IU) for an average American woman, man and a European are 4487.4, 5283.9 and 4214.7 respectively. This calculation is simple and accurate for everyone, even pregnant and lactating women and it will help you keep your required Vitamin D daily intake for optimum blood levels.
The average amount of Vitamin D from food sources (well-balanced diet) is 150 IU/day. Now if you get little or no sun-skin contact, then you should get a supplement corresponding to your needed daily consumption minus the food amount. For example, for a 250 lbs. woman, daily Vitamin D needs would be; 250 X 27 = 6750 IU. If you are able to eat well balanced meals consistently but don’t really get any reasonable sun-skin contact, then you can subtract the amount gained from food, i.e.; 6750 – 150 IU = 6600 IU and work towards this daily rate via supplementation.
If you do get reasonable skin contact, then you should determine from the surface area table just what percentage of sun-skin contact you are getting. For instance, if you are very particular about your food and are somebody like Mark Zuckerberg (who prefers T-shirts, pants and footwear), then you are most likely exposing 11% of your body for varying periods during the day. If your weight is 150 lbs., then your required daily amount is 150 X 27 = 4050 IU. You have to multiply your daily sunlight % with 2, in this case, that makes 22%. Then take 22% of 4050 IU = 891 IU. Therefore your required daily supplementation is; 4050 – 891 – 150 (food) = 3009 IU. (1 International Unit (IU) = 0.025 mcg Vitamin D). 9
Vitamin D is very important for our bodies, but taking it in excess amounts could result in bad side effects like with everything else in this world. Therefore for your own safety and well being make these calculations to know exactly how much supplementation you need. Thus, 5000 IU might be just perfect, too low or high for you – it all depends on the person and there is no universal truth.