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Health & Wellbeing

Vitamin D3 (Cholecalciferol)

Vitamin D3 has well-documented benefits for human health, but can you get too much?

Vitamin D3 (also called Cholecalciferol) is one of five different forms of Vitamin D. Vitamin D3 and D2 are considered essential for human health. We need Vitamin D because it helps us to absorb calcium, magnesium, phosphate, iron and zinc from our foods. However, unlike other vitamins (which cannot be synthesised by the body and must therefore be ingested), Vitamin D can be synthesised by the body, when the skin is exposed to sunlight.

Sources of Vitamin D3

vitamin d3 sunlight
Exposure to sunlight is our greatest source of Vitamin D3.

There are two ways of getting Vitamin D3 into the body - through exposure to sunlight or by ingestion.

Exposure to sunlight is our greatest source of Vitamin D3. The UVB radiation in sunlight enables a reaction in the epidermal layer of our skin to convert a compound, 7-Dehydrocholesterol, into Cholecalciferol (Vitamin D3).

Vitamin D3 can also be obtained through diet, but there are only a small number of foods that naturally contain it: alfalfa, lichen, fish liver oils, ‘fatty’ fish species (salmon, mackerel, tuna, sardines), and eggs and beef and liver contain small amounts.
However, cholecalciferol is also produced industrially for use as a supplement and many ‘fortified’ but processed foods, such as breakfast cereals, contain it.

Vitamin D3 deficiency

A lack of Vitamin D results in impaired bone mineralization and bone damage which leads to bone-softening diseases such as Osteomalacia, also known as Ricketts when it affects children. This condition can cause bending of the spine, bowing of the legs, muscle weakness, increased bone fragility and a higher risk of fractures. Pregnant and breastfeeding women, children under the age of 5 years, older people over the age of 65 years, people who have low or no exposure to sunlight (for example, the housebound) and people who have darker skin tones are more at risk of Vitamin D deficiency. In the UK, pregnant and breastfeeding women are recommended to take Vitamin D supplements (0.01mg) daily.

Health benefits

Aside from the obvious benefits of avoiding the health problems caused by Vitamin D deficiency there has, in recent years, been an increased interest in the other potential health benefits of Vitamin D3. There is evidence that Vitamin D could play a role in preventing/relieving a wide range of severe conditions:

  • Multiple Sclerosis: there some evidence that Vitamin D reduces your risk of developing Multiple Sclerosis (Munger et al., 2006 and Mokry et al., 2015 ), and may also help reduce relapse in those with the disease (Smolders et al., 2008).
  • HeartDisease: studies have indicated that Vitamin D may help in decreasing your chance of developing heart disease (Wang, et al., 2008).
  • Flu: some studies suggest Vitamin D3 can reduce the risks of people developing flu (Urashima et al., 2010).
  • Parkinson's: A 2013 study found that supplementing with Vitamin D3 may reduce deterioration in people with Parkinsons (Suzuki et al., 2013)
  • Alzheimer's: a recent study suggests that there is a link between Vitamin D deficiency and cognitive decline (Miller et al., 2015)
  • Cancer: several studies indicate that lower levels of Vitamin D3 are associated with higher risks of various cancers, including colorectal cancer and breast cancer (Freedman et al., 2008; Garland et al., 2007; Giovannucci, 2007; Goreham et al 2007; Yin et al., 2009).

As it is a relatively new area of research, there is still much to learn about any potential benefits of Vitamin D3, and many more studies are needed before the health benefits of supplementing with Vitamin D3 can be confirmed. However, the early indicators are very positive, and there is hope that, with further understanding of the effects of Vitamin D3 on the human body, we will potentially help to prevent deadly diseases and provide relief to millions of people suffering debilitating conditions such as Alzheimer’s and Multiple Sclerosis .

Too much Vitamin D3

It is impossible to overdose on Vitamin D by over-exposure to sunlight (which should always be avoided for other health reasons) as your body naturally stops producing and absorbing Vitamin D once it has reached equilibrium. However, though rare, people with existing medical conditions (such as hyperparathyroidism) can overdose on Vitamin D by ingesting large amounts of supplemental Vitamin D, causing a condition known as hypercalcaemia - where the body absorbs more calcium than can be excreted.

There is a delicate balance between too much and too little calcium in your blood, and therefore supplementation should remain conservative and within acceptable limits at present despite many doctors recommending a very high daily dosage.

  • Hypercalcemia can also be caused by:
  • Overactive parathyroid glands
  • Cancer.
  • Disease
  • Immobility.
  • Medications
  • Supplements (excessive).
  • Hereditary factors.
  • Dehydration (usually temporary)

Hypercalcemia can cause renal failure and irreversible kidney damage, as well as damaging bone tissue.

Before taking any additional supplements or making any changes to your diet it is always best to discuss it with your doctor first.

Recommend Dosage

A daily vitamin D intake of anywhere between 400 IU and 4000 IU, or 25-100 micrograms with 4000 IU considered a safe upper limit. Anyone with special requirements such as MS who wants to take more should consult with their doctor. Vitamin D intake is recommended at 400-800 IU/day. In certain instances, studies a higher daily intake of 1000-4000 IU (25-100 micrograms) may be appropriate to maintain optimal blood levels.

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