Do You Need More Vitamin D?

Do You Need More
Dr Sarah Brewer
Vitamin D?

Dr Sarah Brewer
MSc (Nutr Med) MA (Cantab) MB BChir RNutr MBANT CNHC
I am a:
‒ Licenced UK Doctor
‒ Registered Nutritionist
‒ Registered Nutritional Therapist
‒ Media consultant
‒ Health journalist
‒ Author of over 60 health books
‒ Health blogger
This presentation explores the importance of vitamin D

What Is Vitamin D?
• The collective term for a group of fat-soluble vitamins
- Made in the skin on exposure to UV light
- Found naturally in very few foods
- Added to some fortified foods
- Available in supplement form
Vitamin D is one of the most commonly deficient
micronutrients in northern latitudes
DrSarahBrewer.com MyLowerBloodPressure.com ExpertHealthReviews.com

Dietary Sources
• Vitamin D2 is derived from plants
- mushrooms exposed to UV light, beans, peas, nuts, seeds
• Vitamin D3 is mainly derived from animals
- Oily fish (sardine, herring, mackerel, salmon, tuna)
liver, eggs, butter, fortified foods
- Recently identified in microalgae & some flowering plants
The average diet supplies 3mcg vitamin D per day

Making Vitamin D3
• UVB sunlight acts on a cholesterol-
like molecule in the skin to create
inactive pre-vitamin D3
(cholecalciferol)
• This undergoes two further
reactions to produce the
biologically active vitamin D
(1,25-dihydroxyvitamin D)
You make some vitamin D3 in your skin on exposure to UV light

Making Vitamin D3
• Inactive 25-hydroxyvitamin D is the
form measured in blood tests
- Although inactive it is stable and has a
relatively long half-life of around 21 days
in healthy people
• 25-hydroxyvitamin D is converted
to active 1,25-dihydroxyvitamin D,
mostly in the kidneys, but also in
some other tissues (eg lungs,
prostate)

Vitamin D3 Is Classed As A Hormone
• A hormone is made in one part of the
body and travels in the circulation to act
on other parts
• But pre-vitamin D3 is only made in the
skin when the UV index is greater than 3
• Earth is tilted - as you go further North or
South from the Equator, less direct
sunlight reaches the ground
• Vitamin D levels plummet during Autumn
and Winter

Skin Synthesis
Many northern countries are covered by a ‘Vitamin D
winter’ for part of the year

It’s A Cover-Up
• Vitamin D status is also low in
those who:
- habitually wear clothes that cover
most of their skin
- stay indoors most of the time
- always use high SPF sun screen
- have dark pigmented skin
NB Glass filters out most UVB rays

Sun Screen
• Used properly, a sunscreen with a
sun protection factor of:
- SPF8 reduces pre-vitamin D3 production in
the skin by 95%
- SPF15 reduces pre-vitamin D3 production by
99%
• Tanning suggests enough UVB
radiation strikes the skin to
stimulate melanin and some
previtamin D3 synthesis

Sun Bathing
• To balance adequate production of
previtamin D3 against skin cancer
risk:
- obtain 10 to 15 minutes sun exposure
to face, arms, hands and/or back
without sunscreen
- two or three times a week

Excess Sun Depletes Vitamin D
• Not everyone produces previtamin D3
efficiently even when the sun shines
- 93 fit, healthy surfers in Hawaii
- 1 in 2 had low vitamin D status
- despite 29 hours sun exposure per week
• This is because excess sun causes
inflammation which breaks down
previtamin D3 before it is absorbed
Binkley N et al 2007. J Clin Endocrinol Metab 92(6):2130-5

It’s An Age Thing
• The ability to synthesise pre-
vitamin D3 falls by at least half
between the ages of 20 to 80 yrs
• One study found that people
aged 62 to 80 years synthesised
four times less pre-vitamin D
than those aged 20 to 30 years
Heaney RP 2006 J Nutr 136 (4): 1123-1125

Why You Need Vitamin D
• Normal absorption of calcium and phosphorus
• Normal blood calcium levels
• Maintenance of normal bones, teeth and muscle function
• Normal function of the immune system
• Normal growth and development of bone in children
• To reduce loss of bone mineral density in post-menopausal women
• To reduce the risk of falling associated with postural instability and
muscle weakness
• For normal cell division
• For immune function

What Is An Optimum Blood Level?
Opinions vary, but the following is a general guide
• Vitamin D blood levels (25-hydroxyvitamin D)
- Deficiency: below 30 nmol/L (12 ng/ml)
- Insufficiency: 30 - 50 nmol/L (12 – 20 ng/ml)
- Adequate: 50 – 80 nmol/L (20 - 32 ng/ml)
- Optimum: > 80 nmol/L (> 32 ng/ml)
- Risk of toxicity: > 125 nmol/L (>50 ng/ml)
• NB A low 25-hydroxyvitamin D plus a raised
calcium suggests a parathyroid tumour
www.parathyroid.com

Who Is Most At Risk Of Deficiency?
‒ Pregnant & breast-feeding women
‒ Breastfed infants (if mothers are deficient)
‒ Children under the age of 5 years
‒ People with dark skin
‒ Over 60s
‒ Those who are frail
‒ Those with limited sun exposure
‒ People with inflammatory bowel disease or
malabsorption
‒ Those with reduced appetite or poor diet
‒ Obese (as vitamin D is fat soluble, more is needed)
In other words, just about everyone!

Vitamin D Deficiency Is Common
• In the UK, Public Health
England found low blood
vitamin D levels in:
- 22% of children aged 11 to 18
- 23% of adults aged 19 to 64
- 21% of adults aged ≥ 65
• In the US, the overall
prevalence of vitamin D
deficiency is 41.6%
Forrest KY, Stuhldreher WL 2011 Nutr Res 31(1):48-54

Symptoms Of Vitamin D Deficiency
• Constipation
• Muscle weakness
• Irritability
• Depression
• Recurrent infections
- eg bacterial vaginosis, colds
• Muscle aches and pains
• Bone pain

Signs Of Vitamin D Deficiency
• Poor growth & bone deformities in children (rickets)
• Softened bones in adults (osteomalacia)
• Loss of bone density (osteoporosis)
• Muscle weakness, falls, hip fracture
• Arterial calcification, hypertension
• Heart failure
Some cancers are associated with
low vitamin D levels
(lung, colon, rectum, breast, prostate, bladder)

Vitamin D & Osteoporosis
• Meta-analysis of data
- 53 trials
- 91,971 older men and women
• Vitamin D plus calcium  hip
fracture risk by 16%
• Vitamin D plus calcium
reduced the risk of any type
of fracture by 5%
Avenell A et al. Cochrane Database Syst Rev 2014 (4):CD000227

Growing Pains
• Vitamin D may protect against growing pains
- 33 children aged 5 – 12 years
- 25-hydrocyvitamin D levels below optimum at 39 nmol/l
- Pain intensity score 7.5
• After 3 months of vitamin D
supplements
- Vitamin D levels increased to 85 nmol/l
- Pain intensity reduced to 2.7
Morandi G et al 2014 J Bone Miner Metab 33(2):201-6

Vitamin D & Type 2 Diabetes
- 21 studies
- Over 76,000 people
• Low vitamin D levels associated with
a 62% increased risk of developing
type 2 diabetes
• Each 10 nmol/L in 25(OH)D levels
was associated with a 4%  risk of
type 2 diabetes
Song Y et al. Diabetes Care. 2013 May;36(5):1422-8

Vitamin D & Depression
- 14 trials
- 31,424 people
• Those with the lowest
vitamin D levels were 31%
more likely to have
depression than those with
the highest level
Anglin RE et al. Br J Psychiatry 2013 202:100-7

Vitamin D & Pregnancy Outcomes
- 15 trials
- 2,833 pregnant women
• Vitamin D supplements  the risk of:
- pre-eclampsia by 48% compared with
no intervention or placebo
- preterm birth by 64% compared to no
intervention or placebo
- low birthweight (below 2500g) by 60%
De-Regil LM et al Cochrane Database Syst rev 2016 (1):CD008873

Vitamin D & The Common Cold
• Vitamin D levels inversely associated with
recent colds in
- 18,883 people in US aged 12 - 60
• Those with the lowest levels (< 25nmol/L)
- were 55% more likely to have had a recent cold
than those with the highest levels (≥75 nmol/L)
- 27% more likely for levels of 25-75 nmol/L
• The association between low vitamin D
levels and colds was:
- 5.6 fold stronger in people with asthma
- 2.3 times greater for people with COPD
Ginde AA et al 2009. Arch Intern Med 169(4):384-90

Vitamin D & Asthma Severity
- 9 trials involving 435 children, 658 adults
• Adding vitamin D to usual asthma
treatment for between 4 – 12 months
reduced the risk of:
- experiencing at least one severe asthma
attack requiring emergency treatment by
61% (from 6% down to below 3%)
compared with placebo
- Needing rescue therapy with oral steroids
by 37%
Martineau SR et al. Cochrane Database Syst Rev 2016 (9):CD011511

Vitamin D & Cancer
- 14 studies
- over 25,000 women
• Women with high vitamin D levels were
significantly less likely to develop breast
cancer than those with low levels
- Every 10 ng/mL increment in vitamin D
level was associated with a 3.2%
reduction in breast cancer risk
• Vitamin D levels are low in 20% to 60% of
people with cancer at diagnosis
Wang D et al. Tumour Biol 2013 34(6):3509-17

Vitamin D & Longevity
• Research in eight countries
- over 26,000 adults aged ≥ 50
• Those with the highest vitamin D
levels were 57% less likely to die,
from any medical cause, during
the study durations than those
with the lowest levels
• Despite vitamin D3 levels varying
with country, sex, and season, the
association within each country
was remarkably consistent
Schottker B et al. BMJ. 2014 Jun 17;348:g3656

Optimising Vitamin D Intakes
• Spend some time out of doors
• Expose some skin to sun for 10- 15 minutes, 2 or 3
times a week
• Eat vitamin D3-rich foods
• Consider taking a vitamin D3 supplement
- Oral tablets
- Mouth sprays
- Skin creams

How Much Vitamin D Do You Need?
• EU RDA is 5 mcg (200 IU)
• US DV is 10 mcg (400 IU)
- These values are based on old understandings relating
to calcium absorption and bones
• Public Health England recently advised:
- everyone in the UK should consider taking a vitamin D
supplement of 10mcg daily (400 IU) during autumn
and winter
• This is a minimum and may not be
sufficient for many people

How Much Vitamin D Do You Need?
• 10 mcg (400 IU) to 25 mcg (1000 IU) is needed
to maintain vitamin D status during
winter
• The elderly may need more
• A US study found 100 mcg (4000 IU) was
needed to maintain vitamin D levels in all
older women
Talwar SA et al 2007. Am J Clin Nutr 86(6):1657-62

Safety
• Both the EU & US suggest the same
tolerable upper intake level for
vitamin D3
 This is 100mcg (4,000 IU) per day for adults
• Excess can lead to high calcium levels
with:
- demineralisation of bone
- kidney stones
- headache
- muscle weakness

Selecting A Vitamin D Supplement
• Select a supplement that:
- Supplies vitamin D3 rather than D2
- Vitamin D3 maintains blood levels better than vitamin D2
- Is made to pharmaceutical standards known as
current good manufacturing practice - GMP or CGMP
Houghton LA, Reinhold V 2006 Am J Clin Nutr 84(4):694-697

Do You Need A MultiVitamin?
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What vitamins & minerals are you lacking?

Thank you for your attention
DrSarahBrewer.com @DrSarahB @DrSarahBHealthy
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Image credits
• Screen Beans
• Bigstock: Yastremska
• Flickr: Julie Falk; David Masters
• Scientific American/vitamindwiki.com

Do You Need More Vitamin D?

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