Vitamin D Deficiency

We all produce vitamin D when sunlight falls on our (unprotected) skin. But how much we produce depends on our age, skin colour, sun strength, and how much of our skin is exposed. Darker skins require more sunlight exposure than lighter skins. Older people are not as efficient at producing vitamin D as younger people.

The sun has to be higher than about 40 degrees above the horizon before you can produce vitamin D in your skin. (That means your shadow should be not much longer than you are, and preferably shorter.) But in many countries, the sun might not reach that high for much of the year. And when it does, many people cover up their skin, or put on sunscreen. The result is widespread vitamin D deficiency.

We can get a limited amount of vitamin D from foods, but not enough.

The benefits of optimum vitamin D are huge and wide-ranging.

Vitamin D Benefits

Vitamin D may protect against

• Alzheimer’s disease
• Bone Loss in old age
• Cancer (including breast, colorectal, liver, lung, prostate, melanoma)
• Dementia
• Diabetes, Insulin resistance and Hyperglycemia
• Falls in older people
• Heart disease
• High blood pressure
• Infections (bacterial and viral)
• Immune system disorders
• Inflammation and pain
• Multiple Sclerosis
• Mood disorders
• Osteoporosis
• Respiratory Tract Infections
• Rheumatoid arthritis
• Seasonal affective disorder (SAD)
• Sports injuries
• Tuberculosis

Vitamin D promotes or enhances

• Bone and tooth health
• Calcium and phosphorus absorption
• Cardiovascular health
• Healthy cell division
• Immune system health
• Insulin sensitivity
• Reproductive system health
• Muscular strength

Vitamin D Dosage

National Academy of Medicine recommendation:

Recommended Daily Allowance for adults: 600 IU (over 70 years: 800 IU)

Safe Upper Limit for adults: 4000 IU

Typical daily intake from food:

150 IU – 300 IU depending on diet.

Our supplementation recommendation for adults:

For men: Winter months: 3000 IU – 4000 IU per day

Summer months: 2000 IU – 3000 IU per day

For women: Winter months: 2000 IU – 3000 IU per day

Summer months: 1000 IU – 2000 IU per day

Take supplemental vitamin D in the form of D3, (the same kind your skin makes when the sun shines on it) not D2 which is less effective. And take vitamin D as oil-filled softgels (not tablets) for best absorption, because vitamin D is an oil-soluble vitamin.

You could take your vitamin D daily, or every 3 days, or even once a week. For example, if you wished to take 1000 IU per day, you could take it as 3000 IU every 3 days, or 7000 IU every week.

Our recommendations are based on what is required to promote sufficiency – not just to avoid severe deficiency.

Vitamin D from all supplements (including multivitamins etc.) should be taken into consideration.

Vitamin D Caution

If under medical care, discuss your intended dose of vitamin D with your doctor. (There may be medical reasons why you should supplement more or less than our recommended amounts.)

Excess vitamin D is toxic – but to reach toxic levels, a person in good health would have to take a lot more than we recommend, for an extended period.

Vitamin D toxicity is therefore very rare. It manifests as too much calcium in the blood (hypercalcemia) and urine.

There are often NO symptoms of this condition initially, but it is very serious, because the body needs to maintain calcium levels in the blood within a specific range. If you have any reason to believe that your vitamin D levels might be too high, get your blood tested. Or you could order a home vitamin D test from ZRT Laboratory. (You have to send it to them for processing.)

Vitamin D Co-Factors

When your body gets optimal amounts of vitamin D, it will absorb more calcium from the food you eat, or from any calcium supplements you might take. To deal with the extra calcium, your body also needs more magnesium and vitamin K2, which help to make sure that the calcium gets where it needs to go (e.g. bones and teeth) and doesn’t deposit in your arteries and kidneys.

Vitamin D Science

For more detailed information about the importance of vitamin D to your health, please see our resources list at the end of this page.

Vitamin D Supplements

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Vitamin D Resources

• Vitamin-D-Health Professional Factsheet
• Vitamin D in Health and Disease
• Nutrition Journal – Current Perspectives on Vitamin D