Vitamin D Supplementation – How Much Per Day?

Vitamin D is important and very beneficial for health. Some people are able to get enough vitamin D from sunlight alone, but others may need to make lifestyle changes or take supplements.

Vitamin D Supplementation


The fact is that many people have vitamin D deficiency.  It is estimated that currently more than a billion people

worldwide are affected with this condition and that is why vitamin D supplementation is one of the most recommended

by doctors today.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin that is stored in the liver and fat tissue. It is different from other vitamins in that the

body is able to produce most of it and is not completely dependent on outside sources. However, as it is stored in adipose

tissue, the increase in body fat has the ability to absorb vitamin D and prevent it from being used properly by the body.

The body makes vitamin D from the conversion of sunlight into chemicals. When UV-B sunlight hits the skin, a substance

called 7-dehydrocholesterol or the cholesterol in our skin converts it and makes it useful, first it goes to the kidneys and

liver and then is converted into a biologically active and usable substance called calcitriol. 

Vitamin D actually becomes a hormone within the body, particularly a secosteroid hormone. It is a precursor to a

steroid hormone and affects skeletal structure as well as blood pressure, immunity, mood, brain function and the

ability to protect us from cancer.

Vitamin D in the diet

There are two types of vitamin D, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D precursor

is found in plant and animal products, but vitamin D3-derived products are believed to be more absorbable and beneficial.

Vitamin D2 is created by irradiating yeast and other fungi or animal oils and cholesterol. The type of vitamin D that

the body naturally produces is called cholecalciferol, which is vitamin D3. It is able to convert D2 to be used for body

functions, but prefers and is able to use vitamin D3 much more effectively.

Most vitamin D fortified foods and dietary supplements primarily contain vitamin D2, which the body does not

effectively absorb or convert to what it needs. Animal-derived D3 is the closest thing to what sunlight naturally

produces in humans when the skin works to convert UV rays. Vitamin D3 is believed to be converted up to 500 times

faster than D2 and can be up to four times more effective in humans.

The sun and vitamin D

For many, the main ways to get vitamin D are drinking milk, eating fish, or even taking supplements

like cod liver oil. Yes, these are sources of vitamin D, but direct sun exposure is actually the best way to

absorb it.

Exposure to the sun for approximately 10 minutes without using sunscreen allows the body to absorb about 10,000

units of natural vitamin D, but this amount is not a rule of thumb as it can be different for each person. This is because

the amount of melanin present in the skin affects the amount of vitamin D produced.

Melanin is a substance that affects skin color, meaning the more melanin is present, the darker the skin color and it

is released when we are exposed to the sun’s ultraviolet rays. The more sun we get, the more melanin is released into

our skin. It is estimated that about 90% to 95% of vitamin D in most people comes from casual sun exposure, where

after receiving the sun, cholesterol in the skin converts melanin into usable vitamin D to be distributed throughout the body. .

Main causes of vitamin D deficiency

One of the main causes of vitamin D deficiency is caused by the modern lifestyle, which conditions people to stay

indoors most of the day.

– Lack of sun

Modernity has conditioned the population to spend more time indoors without contact with sunlight. Adults work

indoors all day, exercising in gyms and the rest of the time they are indoors. Most children spend hours watching

television, playing video games and surfing the internet.

The result of this sun deprivation is vitamin D deficiency, which currently affects more than a billion people worldwide.

– Sunscreen

The first fact is that we don’t take the necessary amount of sun and the second is that when we do, we use sunscreen.

Due to the alarming statics of skin cancer, today we are all encouraged to use sunscreen at all times and seasons of

the year.

Research shows that the use of SPF 8 protector already reduces the body’s ability to absorb vitamin D by 90%. If the

sunscreen is SPF 30 or higher, vitamin D absorption drops to 99%. This means that there is no point in spending

time outdoors using sunscreen, as it does not allow our bodies to convert vitamin D from the sun.

Research also shows that some health conditions, such as obesity, type 2 diabetes,  insulin resistance  and hypertension,

contribute to an increased risk of vitamin D deficiency.

Vitamin D Deficiency Symptoms

People with vitamin D deficiency are predisposed to develop health complications and diseases such as cardiovascular

disease, metabolic syndrome , various types of cancer, immune disorders and adverse pregnancy outcomes. According

to several studies and scientific analyses, vitamin D deficiency symptoms may be related to the following health problems:

  • Osteoporosis;
  • Heart disease;
  • High pressure;
  • Cancer;
  • autoimmune diseases;
  • Depression;
  • Insomnia;
  • Arthritis;
  • Diabetes;
  • Asthma;
  • Multiple sclerosis;
  • Chronic pain;
  • Psoriasis;
  • Fibromyalgia;
  • Autism.

Research also suggests that anyone with these health conditions or the following symptoms should be screened for

possible vitamin D deficiencies:

  • Weakness;
  • Chronic fatigue;
  • Depression;
  • Difficulty sleeping;
  • Anxiety;
  • Weak or broken bones;
  • Weakened immune system;
  • Inflammation and swelling.


A test called a 25-hydroxy vitamin D test can be done to investigate a possible deficiency.

  • 50+ is considered a good level of vitamin D.
  • 30 to 50 means you need vitamin D supplementation. This means spending more time in the sun and adding vitamin D-rich foods to your diet.
  • -30 means you are very deficient and need to take immediate action to raise levels.

Talk to your doctor about supplementing with higher doses of vitamin D if you have a deficiency or a very low level.

Another detail is that some other types of vitamin D tests can show normal or even elevated levels of vitamin D,

which are really inaccurate and can hide a serious deficiency. So the 25(OH)D test appears to be the most accurate

in determining your true vitamin D levels.

Vitamin D Supplementation – How Much Per Day?

How much vitamin D you need depends on many factors. It is necessary to understand your age, race,

where you live, season of the year, exposure to the sun, types of clothes you use and much more.

The US Institute of Medicine recommends that the average daily intake of vitamin D be 400 to 800 IU, or 10 to 20 micrograms –

it is estimated that this is the proper amount for 97.5% of people. However, some studies have shown that the daily

intake needs to be higher if there is no sun exposure.

A study of healthy adults showed that a daily intake of 1120 to 1680 IU was needed to maintain sufficient blood

levels. In the same study, individuals with vitamin D deficiency required 5000 IU to reach blood levels above 30 ng/ml.

Overweight or obese people may also need higher amounts of vitamin D.

All in all, a daily vitamin D intake of 1000 to 4000 IU, or 25 to 100 micrograms ,  should be enough to ensure optimal

blood levels for most people. The 4000 IU reference is the safe upper limit according to the Institute of Medicine (IOM).

Make sure you don’t take more than this without consulting a health care professional.

Main sources of vitamin D

Vitamin D can be obtained through sun exposure, eating foods that contain vitamin D and also vitamin D supplements

. Check out some of the main sources below:

1. Food

Increasing your intake of vitamin D foods is one of the best ways to avoid a deficiency and promote overall health.

Children under 12 months need at least 400 IU per day and people between the ages of 1 and 70 years need 600 IU per day.

Older adults need more vitamin D and should get at least 800 IU of vitamin D a day.

  • Cod Liver Oil:  1 tablespoon contains 1360 IU (above 100% of daily values).
  • Wild Salmon:  Approximately 100 grams contain 447 IU (above 100% of daily values).
  • Mackerel:  Approximately 100 grams contain 306 IU (76% of daily values).
  • Tuna:  Approximately 100 grams contain 154 IU (39% of daily values).
  • Fortified Milk:  1 cup contains 124 IU (31% of daily values).
  • Sardines:  2 sardines contain 47 IU (12 of daily values).
  • Bovine liver:  Approximately 100 grams contain 42 IU (11% of daily values).
  • Eggs:  1 egg contains 41 IU (10% of daily values).
  • Fortified Cereal:  1 cup contains 40 IU (10% of daily values).
  • Caviar:  1 tablespoon contains 37 IU (9% of daily values).
  • Mushrooms:  1 cup contains 2 IU (1% of daily values). 

Those who don’t consume fish can get through foods like eggs and mushrooms as well as fortified products like cereal juices

and dairy products.

2. sunlight

Sun exposure is the best way to get vitamin D. However, the amount of sunlight needed varies. For example, older

people and dark-skinned people produce less vitamin D in their skin, and factors such as clothing, climate, pollution,

sunscreen use, weight and genetics can also affect the body’s ability to produce vitamin D.

During strong sunlight, exposing arms and legs for 5 to 30 minutes between 10 am and 3 pm is usually sufficient to meet

the daily needs of most fair-skinned people. People with darker skin may need a little more time. This time usually

guarantees 100% of daily needs.

3. Supplements

Vitamin D supplements are very affordable and can provide a potent dose of vitamin D, being able to meet daily needs

in just a single dose. It is important to consider that if there is a deficiency, the doctor needs to assess whether vitamin D

supplementation is necessary or whether you can meet your needs with only vitamin D-rich foods.

If there is an interest in taking a supplement, opt for a high-quality food-based multivitamin whenever possible and

select a form that uses vitamin D3 instead of vitamin D2 to help maximize absorption.


Vitamin D-rich foods can help lower the risk of deficiency, but they are most effective when combined with regular

sun exposure whenever possible. In some cases, supplementation may also be necessary to ensure you meet your needs.

As vitamin D is a fat-soluble vitamin, its consumption must be combined with healthy fats to help maximize absorption.

Foods such as ghee, coconut oil, butter, extra virgin olive oil, nuts and seeds are excellent choices to help increase the

bioavailability of vitamin D in the body.

Also consider that vitamin D toxicity is possible, although it is usually caused by supplementation rather than exposure

to sunlight or dietary sources. High doses of vitamin D supplementation can cause symptoms such as vomiting,

weakness, nausea, and frequent urination. If you do decide to take vitamin D supplements, be sure to apply the

recommended dose to avoid adverse side effects.

Vitamin D overdose?

Vitamin D overdose and toxicity is extremely rare, but it is associated with dangerously high amounts of calcium and

phosphates in the blood, along with low levels of parathyroid hormones. It is possible to diagnose this condition in

people who have taken extremely high doses of vitamin D accidentally or intentionally for long periods, such as 50,000

to 1 million IU/day for months.

The upper level of harmless intake is set at 4000 IU, or 100 micrograms, per day. However, one study reported

that up to 10,000 IU per day has not been shown to harm healthy individuals.

It is worth emphasizing that large doses may not cause harm or toxicity, but are completely unnecessary.

Vitamin D is essential for bone health and many other aspects of health. Lifestyle and modernity are making

disability incredibly common and this can have health consequences.

If you’re thinking about adding more vitamin D to your diet, consider daily exposure to sunlight, try a walk in

the park, exercise outdoors, and that walk after lunch. Attitudes like these can already guarantee your daily levels.

Another way is to ensure you eat foods rich in vitamin D and combine with healthy fats to help maximize absorption.

If you don’t have as much access to the sun and your diet is deficient, vitamin D supplementation should suffice,

but the only way to know if you really need to take vitamin D supplements is through a test. Fixing a deficiency is

simple, inexpensive, and can have immense health benefits.

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