alt= Worldwide Shipping from the USA and UK
TestoFuel Blog : Make Gains & Pack on the Muscle

Vitamin D3 Deficiency: Symptoms and Treatment

Achieving good health, wellness and longevity is about optimal nutrition, being physically active on a regular basis and enjoying life.

But while a diet rich in vitamins, minerals and nutrients can promote an athletic and aesthetic physique, a lack of good nutrition can lead you down the slippery slope of illness and disease.

In this article we take a look at vitamin D3 – the sunshine vitamin as its otherwise known.

Many people just don’t get enough of this wonder nutrient, and nearly half of the US population have a deficiency.

If you want to know more about the symptoms and treatment of vitamin D3 deficiency you’re in the right place.

What is Vitamin D3?

Vitamin D is one of four fat-soluble vitamins (the others being vitamin A,E and K).

It is stored and dissolved in your fatty tissue rather than in water, the benefit of this being that it can store in your body for long periods of time.

Where vitamin D differs from other nutrients though is it’s not technically a vitamin – it’s a hormone produced from cholesterol when your body is exposed to the ultraviolet rays of the sun.

The sixth steroid hormone

Vitamin D is often referred to as a steroid hormone because it has a potent effect on other hormones. In the research you’ll often find it labelled as a secosteroid, purely due to its action on the endocrine system.

It acts kind of like a chaperone, guiding nutrients into manufacturing other important hormones.

There are two forms of the nutrient:

  • Ergocalciferol – D2
  • Cholecalciferol – commonly referred to as D3

Vitamin D3 it’s much more bioavailable than ergocalciferol – in fact, taking a D2 dose can actually reduce D3 levels [1].

The sunshine vitamin

Unless you live in a hot, sunny climate you’re more than likely not getting enough of this steroid hormone in your body to ensure good health.

In fact, current statistic suggest that over 40% of US citizens are deficient in vitamin D [2].

And in women this figure can be as high as two-thirds.

You’ll find vitamin D in some foods – but not in great amounts

D2 can be found in foods such as mushrooms, fortified milk and cod liver oil. You’ll find D3 in foods such as oily fish (salmon, sardines etc.), egg yolks and beef liver.

The problem is though that while the sun gives you pretty much all of the stimulus you need to make D3, very few foods provide your recommended daily allowance of the hormone.

According to one of the biggest review studies ever done on the nutrient, ‘very few foods naturally contain or are fortified with vitamin D’ [2].

For example, one large egg only gives you 7% of your recommended amount – and even oily fish can provide only 75% of what you need for optimal health.

That’s where a supplement comes in handy.

Man in pink shorts on the beach in the sun

Key Point: Vitamin D3 is the more potent version of the steroid hormone. The major source of this fat-soluble hormone is the sun – but you’ll also get small amounts from food too.

How Much Vitamin D Do You Need?

There’s a fair bit of controversy when it comes to getting the right amount of vitamin D.

That’s because the current recommended RDA set by bodies such as the National Academies of Science is only 600 IU per day [3].

Many believe that this is far too low – especially when it comes to those that don’t live in sunny climates all year round.

The current RDA came from figures based on mean averages using a wide range of different people, but there was a high variability in exactly how much vitamin D people needed.

Most people will need more than this.

If you look at more recent clinical studies, higher D3 doses have been shown to improve both health and performance.

A comprehensive range of studies have shown that daily doses of 2,000-5,000 IU are optimal – particularly for those that are physical active [4].

“It is estimated that the body requires 3000–5000 IU of vitamin D per day to meet the needs of essentially every tissue and cell in the body”.

Male model man smiling on blue background

Key Point: Daily doses of 2,000-5,000 IU Vitamin D3 seem to most appropriate in supporting health and performance.

Symptoms of Low Vitamin D3 Levels

Combine the possible lack of sunlight and the low bioavailablity of food-based vitamins with the high daily needs of vitamin D and you can see why so many people are deficient in this nutrient.

But how would you know that your D3 levels are low?

Muscle weakness and poor physical performance

One of the molecular mechanisms of vitamin D is protein synthesis.

This is because the hormone converts to calciferol in the body and is then able to adapt the specific genes responsible for regulating muscle mass [5].

More vitamin D means more potential for muscle mass.

If you’ve experienced a sudden drop in sports performance or your gym workouts are feeling heavy and hard then your vitamin D3 could be low.

Excessive muscle soreness

Soreness from hitting the gym a little too hard is completely normal. But excessive amounts isn’t.

An inability to recover from exercise can indicate low D3 levels.

One study, published in Nutrition and Metabolism, found that 4,000 IU of the vitamin helped a group of athletes reduce delayed muscle soreness from exercise by 50% [6].

Low mood and depression

We all feel a bit down when the dark nights draw in and those summer bbqs have to come to an end for another year.

But there’s an actual physiological explanation as to why a lack of sun can cause low mood, depression and seasonal affective disorder. And it’s to do with receptors.

That’s because vitamin D receptors can target a specialized part of the brain called the hypothalamus. This regulatory gland plays a huge role in controlling the neurotransmitters that regulate aspects of mental health – including mood [7].

Decreased energy

Feeling sluggish, lethargic and constantly tired can be a surefire sign that your hormones just aren’t where they should be.

Vitamin D3 directly stimulates androgen production. And if your testosterone levels are low, you could well blame a D3 deficiency.

Numerous studies have shown that low vitamin D levels lead to reduced testosterone levels. And this in turn can lead to a number of issues such as:

  • A lack of energy, vigor and stamina
  • Low libido and sex drive
  • Reduced muscle and bone mass
  • Decreased strength, power and endurance
  • Increased belly fat and ‘man boobs’

Clinical trials show that taking a vitamin D3-based supplement can restore testosterone levels, and as such can help to raise your energy levels, shred belly fat and restore your mood, muscle mass and strength too.

Bone pain

One of the major roles of D3 is to regulate the amount of calcium and phosphate in the body and as such, promote a healthy skeleton.

When you are low on sunshine hours or vitamin-rich foods, you can experience tenderness, discomfort and pain in your bones.

A lack of hormonal stimulus on bone tissue can lead to a loss of minerals – and that results in soft and brittle bones that cannot support your body mass as effectively.

It can lead to deformities and postural problems if not corrected.

Older man looks out to the ocean whilst showing off his muscular body

Key Point: Vitamin D3 deficiency symptoms include low mood, a loss of muscle strength, poor recovery from exercise and low testosterone levels.

How to Treat Low Vitamin D Levels

The great thing about the human body is that it is a dynamic machine.

Your hormones are constantly trying to adapt and acclimatize to the environment around it. This means that you can quickly correct deficiencies with the right strategies.

Here’s how to properly treat your low D3 levels…

Go on holiday

Unfortunately we can’t tell you to hand in your notice at work and move to a Caribbean island. But what we can do is recommend a holiday somewhere nice and warm – even if it’s just for a few days.

The effect of sunlight on vitamin D3 status is unquestionable and one of the most effect ways of correcting hormonal balance.

It’s one of the main reasons we feel so good when we’re sat on the beach (the cocktails help of course).

Use a supplement

The problem with tours around the sunnier climates of the world is that it can be expensive.

A supplement provides your best alternative to sunlight because it is both high in bioavailability and easy to fit into your busy schedule.

Supplements are simple, easy and effortless ways of ensuring you get all of the nutrients you need to boost health, vitality and vigor.

Eat more oily fish

Salmon, mackerel, tuna fish and sardines are great for heart health and high in protein. You’d need to eat a huge amount to hit your recommended daily amounts – but it certainly helps.

Just watch out for that oily fish because it an be high in calories too.


  1. Holick, MF et al. Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline. JCEM. 2011; 96(7): 1911-1930
  2. Lehmann, U et al. Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial. J Clin Endocrinol Metab. 2013; 98(11): 4339-45
  3. National Institutes of Health. Vitamin D.
  4. Ogan, D et al. Vitamin D and the athlete: risks, recommendations, and benefits. Nutrients. 2013; 5(6): 1856-1868
  5. Pfeifer, M et al. Vitamin D and muscle function. Osteoporos Int. 2002; 13(3): 187-94
  6. Barker, T et al. Supplemental vitamin D enhances the recovery in peak isometric force shortly after intense exercise. Nutr Metab (Lond) 2013; 10: 69
  7. Bertone-Johnson, E. Vitamin D and the Occurrence of Depression: Causal Association or Circumstantial Evidence? Nutr Rev. 2009; 67(8): 481-492