Vitamin D3: Dosage, Deficiency and Health Benefits

Vitamins – is there really any benefit to taking them and do they work?

Yes, according to science.

Vitamins are essential nutrients your body needs to work properly and stay healthy1. These days, it seems to be seriously difficult to get all the essential nutrients and minerals you need through your diet. That’s why more people are supplementing with vitamins.

One such nutrient is the ‘sunshine vitamin’, vitamin D. In this article, we’ll explain what it does, why it’s so beneficial, how much of it you need, and the risks associated with taking too much. Keep reading to find out how you can ‘vitamin D-fend’ your health!

What is vitamin D?

Vitamin D is needed to regulate the amount of calcium and phosphate in your body which in turn works to keep your bones, muscles and teeth healthy. It is different than most other vitamins because it can be synthesized by the sun and essentially functions as a hormone.

It may also have other beneficial roles in the body, contributing to the normal working of the immune system, muscle function and ensuring your blood has suitable calcium levels.

Vitamin D is produced when your skin is exposed to sunlight. The problem is, many people don’t get enough sun because of where they live or work.

Vitamin D3

What is the difference between D and D3?

Vitamin D3, also known as cholecalciferol, is the bioavailable and recommended form of vitamin D. It is the natural form that your body produces, either from the sun or through certain foods.

Vitamin D3 is mainly found in animal-sourced foods and is better absorbed by our bodies. D3 can be found in:

  • Fatty fish such as mackerel, salmon and tuna
  • Cheese
  • Egg yolks
  • Milk
  • Red meat

Vitamin D3 is believed to be more important for your wellbeing because of its effectiveness in raising active levels of vitamin D in your body.

D3 is first metabolized in the liver and converted to calcidiol, the storage form of vitamin D. It is then converted to calcitriol in the kidneys which is the active, circulating form of vitamin D2.

The more calcitriol in your blood, the more active vitamin D you will have in your body. Vitamin D3 has been shown to significantly raise blood levels of calcitriol3.

Health benefits of vitamin D

When people think about the health benefits of vitamin D, they think about their bones. But there’s more to vitamin D than bones!

This powerful nutrient can almost act as an antioxidant with benefits that influence all aspects of health. Below are the most common benefits associated with vitamin D:

  • Better mood

If you suffer from seasonal affective disorder (SAD), you might want to up your vitamin D levels. This highly potent vitamin could be the mood booster you’ve been waiting for.

It has been shown to play a major role in regulating mood and defending against depression – one study found that depressed people who consumed vitamin D supplements observed an improvement in their symptoms4.

Low levels of vitamin D3 have also been associated with mood difficulties and challenges such as memory and concentration as well as cognitive decline in adults in later years5.

  • Flu fighting

Influenza, also known as the flu, is a serious and contagious respiratory infection which can affect anyone at any age and wreaks the most havoc over the winter months.

Clinical studies have shown vitamin D to protect against respiratory tract infections6 such as the flu, so be sure to add it to your supplement list whenever you feel a little under the weather.

  • Increased bone and muscle strength

We know that vitamin D is known for its bone-boosting health benefits. It may also prevent osteoporosis, a health condition that weakens your bones, making them more likely to break.

Without enough vitamin D, your body can’t effectively absorb calcium which is vital for good bone health. Clinical studies support this – in one study on older individuals, a high dose of vitamin D was shown to potentially reduce fractures by at least 20% for individuals aged 65 years or older7.

For muscle building, vitamin D earns its benefits from the way it increases testosterone. Testosterone is a powerful hormone that plays a major role in your ability to build muscle gains8. Increase your testosterone levels (via vitamin D) and you may be able to add some more mass to your muscles.

There is a direct link between low vitamin D and low testosterone levels – in one study, participants that increased their sun exposure increased their vitamin D levels alongside their testosterone9. Exposure to sunlight has been shown to signal the release of luteinizing – a pituitary hormone that produces testosterone. One study found that luteinizing levels increased by 69.5 per cent in 11 healthy men after being exposed to bright light in the early morning10.

  • Cancer treatment

Cancer is the second main cause of deaths worldwide, according to the World Health Organization (WHO).

Vitamin D consumption may play a huge role in this disease. This is because it’s thought to help control normal cell growth and may be able to stop cancerous cells from growing. It has been indicated that people with decreased levels of vitamin D are also at a much greater risk of cancer11.

One study also found that vitamin D may help cancer patients live longer if taken for at least three years12.

  • Weight loss

Being overweight can have a serious impact on your health. WHO has declared that the condition is an epidemic of the 21st century – so finding ways to target and treat obesity are increasingly welcomed. Vitamin D supplementation may have an impact on weight loss.

Overweight individuals tend to have lower levels of vitamin D and several studies exist to back this up13. Interestingly, increasing your vitamin D intake may enhance weight loss and positively impact body fat14.

Vitamin D and deficiency

First things first, what causes vitamin D deficiency?

You can become deficient in these five ways:

  • You don’t get enough vitamin D through your diet
  • You don’t get enough sun
  • You can’t absorb enough vitamin D from food
  • Your liver or kidneys cannot work to convert vitamin D to its active form
  • Your medications interfere with your body’s function to convert or absorb vitamin D

Vitamin D deficiency is extremely common, and the signs and symptoms are so subtle that you’re unlikely to notice your deficiency for several years. This is why it is dubbed a silent epidemic.

Up to 50% of the world’s population are said to be vitamin D deficient15. This data can mainly be attributed to lifestyle – without enough sun exposure or if you fail to eat the right foods, you are likely to have a vitamin D deficiency.

How can you know if your body isn’t getting enough vitamin D?

Signs and Symptoms of Vitamin D deficiency

Vitamin D deficiency is more common in adults aged over 55, people with darker skin or those with kidney and liver disease. Those with GI tract conditions like coeliac disease can also experience a vitamin D deficiency.

If you are overweight, spend most of your time indoors or live somewhere where there is little sun around, you may also have an increased risk.

The following signs and symptoms are associated with vitamin D deficiency:

  • Fatigue and tiredness
  • Rickets
  • Depression
  • Brittle bones
  • Regular respiratory tract infections
  • Impaired wound healing
  • Muscle pain

Recommended Intake of Vitamin D

The amount of vitamin D you need can vary because of your current levels. Since the majority of people can’t get enough from their diet, taking a supplement may be the best way to reach adequate levels.

According to the Department of Health, the recommended daily allowance of vitamin D is 10 micrograms.

In certain circumstances, you may need a larger dose – especially if your current blood levels are low. If you’re unsure, we recommend that you have your vitamin D levels checked by your physician before taking a supplement.

When choosing your vitamin D supplement, try and find one that contains D3 (cholecalciferol) as it will work better at raising your blood levels of vitamin D16.

Like with any supplement, you need to be cautious of taking too much. Recommended amounts vary from one organization to the next, but doses of 1000-2500mcg per day have been shown to cause toxicity after several months17.

Vitamin D3: your FAQ’s answered


How much vitamin D3 should you take a day?

It is possible to take too much vitamin D; however, toxicity is uncommon. Try and stick to 5000 IU per day at the most – this is what the Vitamin D Council recommends as treatment for low testosterone18.

What are the benefits of taking vitamin D3?

Vitamin D works in many parts of the body including your bones, immune system, brain and nervous system. It may also play a part in regulating insulin levels and supporting cardiovascular health.

Most people take vitamin D to protect their bones and ward off bone diseases, but it can also improve symptoms of Seasonal Affective Disorder (SAD) as well as defending against respiratory infections.

When should I take vitamin D3?

Vitamin D3 is a fat-soluble vitamin which means it is best absorbed when combined with high-fat foods. For this reason, it is best to take vitamin D supplements after a meal to boost absorption. Many people take them first thing in the morning as it can be easier to remember.

Is it better to take vitamin D every day or once a week?

Vitamin D is typically taken daily but this isn’t always necessary. Your dosage would depend on where you live (whether it’s somewhere sunny), the time of year, or if you have any risk factors for vitamin D deficiency. Check with your physician first to find out what your adequate dosage is.

What foods have vitamin D3?
Sources of vitamin D include:

  • Fatty fish such as mackerel, salmon, sardines and tuna
  • Mushrooms
  • Cheese
  • Egg yolks
  • Margarine
  • Some breakfast cereals
  • Milk
  • Red meat

Get your Vitamin D fix from Instant Knockout Cut

You’ll find this important vitamin in the Instant Knockout Cut formula.

As the leading weight management supplement – and the only one trusted by real athletes – we’ve cut no corners in developing a product that really fires up your body’s fat shredding potential and maximizes performance. In the formula, you get a generous 45mcg of Vitamin D3 (Cholecalciferol) per serving – which is vegan friendly too.

The bottom line

Vitamin D is essential to so many important processes in the body however vitamin D deficiency is extremely common.

If you spend a lot of time indoors or don’t eat a lot of foods containing vitamin D, you should consider supplementing.