potential health benefits of vitamin d and omega-3 fatty acids nimal ratnayake, ph.d...
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Potential Health Benefits of Vitamin D and Omega-3 Fatty Acids
Nimal Ratnayake, Ph.D.
Senior Research Scientist
Nutrition Research Division
Health Canada Hindu Temple of Ottawa-Carleton
April 8, 2012
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What is vitamin D?
Vitamin D – Fat soluble vitamin
Naturally present in very few foods
Also produced when ultraviolet rays
from sunlight strike the skin, interacts
with cholesterol (7-dehydrocholesterol)
in the skin and trigger vitamin D
synthesis.
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Main Physiological function of vitamin D
Vitamin D promotes calcium & phosphorous absorption in the gut
Maintains adequate serum calcium & phosphate concentrations-
Critical for bone growth and maintaining bone health.
Without sufficient vitamin D bones can become thin, brittle, or
misshapen.
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Vitamin D deficiency & Health
• Rickets and osteomalacia (softening of bones) are the classical
vitamin D deficiencies
• In children, vitamin D deficiency causes rickets, a disease characterized by a
failure of bone tissue to properly mineralized, resulting in soft bones and skeletal
deformities.
• Rickets was first described in the mid-17th century in Briton. In the late 19th and
20th centuries, researchers noted that consuming 1-3 teaspoons of cod liver oil
could reverse rickets
• The fortification of milk with vitamin D beginning in the 1930s has made rickets a
rare disease in the US and Canada.
• But it still reported periodically, particularly in dark-skinned infants breastfed by
mothers, children in daycare programs (less exposure to sunlight) and
immigrants from Asia, Africa and Middle East (because of differences in vitamin
D metabolism, and behavioral differences that lead to less sun exposure).
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Vitamin D deficiency and Health
• In adults vitamin D deficiency can lead to osteomalacia
(softening of bones), resulting in weak bones.
• Symptoms include bone pain and muscle weakness, but such
symptoms can be subtle and go undetected in the initial stages.
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Vitamin D Deficiency and Health - Osteoporosis
• A disease characterized by low bone mass and structural deterioration
of bone tissue that causes bones to become, thin and porous & fragile
and leading to increase risk of bone fracture.
• The most common sites of osteoporotic fracture are the wrist, spine &
hip.
• 1 in 3 women and 1 in 5 men in Canada will suffer from an osteoporotic
fracture during their life time.
• The cost to the Canadian health care system of treating osteoporotic
fractures is currently estimated to be $1.9 billion annually.
• No single cause for osteoporosis has been identified.
• However, most often it is associated with inadequate calcium intake,
but insufficient vitamin D contributes to osteoporosis by reducing
calcium absorption.
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Vitamin D Deficiency- Role in other health problems
Many laboratory animal studies, some, but not all, human clinical and
epidemiological studies have also linked low vitamin D levels to an
increased risk of health problems:
Cancers: colon, prostate and breast cancers
Type 1 and Type 2 diabetes
Glucose intolerance
Hypertension
Multiple sclerosis
Cardiovascular disease
Note: The Food and Nutrition Board of the US Institute of Medicine (IOM)
in 2011, based on extensive review of the scientific literature, concluded
that most published health benefits associated with vitamin D provide
mixed & inconclusive results and could not be considered reliable.
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Serum concentration of 25-hydroxy Vitamin D (25(OH) D is
the best indicator of Vitamin D status
Vitamin D Status
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Serum vitamin D concentration & Health
Serum Vit.
D (nmol/L)
Health Status
<30 Vitamin D deficiency, rickets in children & osteomalacia in
adults
30-50 Inadequate for bone & overall health in healthy individuals
≥50 Adequate for bone & overall health in healthy individuals
>125 Potential adverse effects
Ref. US Institute of Medicine (2011)
(The levels identified by the US institute of medicine in
its extensive review of literature)
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Recommended Daily Dietary intake for Vitamin D
Age Male Female Pregnancy Lactation
0-12 months 400 IU
(10 mcg)
400 IU
(10 mcg)
1-13 years 600 IU
(15 mcg)
600 IU
(15 mcg)
14-50 years 600 IU
(15 mcg)
600 IU
(15 mcg)
600 IU
(15 mcg)
600 IU
(15 mcg)
51-70 years 600 IU
(15 mcg)
600 IU
(15 mcg)
> 70 years 800 IU
(20 mcg)
800 IU
(20 mcg)
Ref. US Institute of Medicine, 2011
Intake levels recommended for maintaining a serum vitamin D
concentration of >50 nmol/L (adequate for bone & overall health in healthy individuals
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Sources of vitamin D
Foods
Foods fortified with vitamin D
Supplements
Sunlight (ultraviolet (uv) B radiation)
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Sources of vitamin D: Food
Food IUs per serving Percent Daily Value
Cod liver oil, 1 tablespoon 1360 340
Salmon, cooked, 3 ounces 447 112
Tuna, canned in water, 3
ounces
154 39
Liver, beef, cooked, 3 ounces 42 11
Egg, 1 large (Vit D found in
yolk)
41 10
Cheese, Swiss, 1 ounce 6 2
Very few foods in nature contain vitamin D. Liver oils and fatty fish (salmon, mackerel)
are the best sources. Small amounts are found in beef liver, cheese & milk.
Foods providing 20% or more of DV are considered to be high sources.
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Sources of vitamin D: Foods Fortified With Vitamin D
Food IUs per serving Percent Daily Value
Orange juice, fortified with Vit D 137 34
Milk, whole, vit D fortified, 1 cup 124 31
Yogurt, vit D fortified, 6 ounces 80 20
Margarine, fortified, 1 table
spoon
60 15
Cereal, fortified with vit D 40 10
Orange juice, milk, yogurt, margarine, and many other foods contain added Vit D.
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Vitamin D Sources- Sun exposure
Most people meet their vitamin D needs through exposure to sunlight.
Ultraviolet (UV) light B radiation with a wavelength of 290-320 nanometers
penetrates uncovered skin and converts cutaneous cholesterol to vitamin D
5-30 min of sun exposure between 10 am and 3 pm at least twice a week
to the face, arms, legs or back without sunscreen cream usually lead to
sufficient vitamin D synthesis.
According to the Vitamin D Council of the USA, young adult Caucasians
produce about 20,000 IU of vitamin D in their skin within minutes of whole-
body, summer sun exposure. In other words, light skinned individuals could
greatly exceed the vitamin D intake recommendations simply by spending
a few minutes outside in their swim suites.
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Factors that affects sun light exposure
Season (ample opportunities exist to form vitamin D during spring, summer
and fall months even in the far north latitudes)
Complete cloud cover reduces sun UV radiation by 50%
Skin melanin content (brown/dark skin people produces less vitamin D than
light skin people)
Sunscreens with a sun protection factor of (SPF) of 8 or more appear to
block vitamin D producing UV rays.
UVB radiation does not penetrate glass, so exposure to sunshine indoors
through a window does not produce vitamin D.
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Sun exposure - danger of over exposure
Sun UVB radiation is a carcinogen (UV radiation is responsible for most of
the 1.5 million skin cancers and the 8000 deaths due to metastatic
melanoma that occur annually in the US)
Life time cumulative UV damage to skin is also largely responsible for
some age-associated dryness and other cosmetic changes.
Because of these public health concerns, it is prudent to limit the exposure
to sunlight.
There are no studies to determine whether UVB-induced synthesis of
vitamin D can occur without increased risk of skin cancer.
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Groups at risk of vitamin inadequacy
Breastfed infants
Vitamin D requirement (400 IU) cannot ordinarily be met by human milk alone, which
provides 25 to 78 IU/L. Breast fed infants be supplemented with 400 IU per day.
Older adults
Older adults are at increased risk of developing vitamin D insufficiency in part because,
as they age, skin cannot synthesize vitamin D efficiently. Supplement with 800 IU per
day
People with dark skin
Greater amounts of the pigment melanin in the epidermal layer result in the darker skin
and reduce skin’s ability to produce vitamin D from sunlight. Various reports consistently
show lower serum levels of vitamin D. However, it is not clear that lower levels of vitamin
D for persons with dark skin have significant health consequences.
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Groups at risk of vitamin inadequacy
People with fat malabsorption
As a fat soluble vitamin, vitamin D requires some dietary fat in the gut for absorption. Fat
malabsorption is associated with a variety of medical conditions including some forms of
liver disease, cystic fibrosis and Crohn’s disease.
People who are obese
A body mass index ≥ 30 is associated with vitamin D insufficiency. Obesity does not
affect skin’s capacity to synthesize vitamin D, but greater amounts of subcutaneous fat
sequester more of the vitamin and block its release into circulation.
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Mean plasma vitamin D levels of Canadians, 2007-09
Age group (years)
Pla
sm
a v
itam
in D
(n
mo
l/L)
Adequate level
for overall health
Whiting et al. AJCN 2011:94, 128-35
National data on vitamin D Status in the Canadian Health Measures Survey (n=5306)
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Percentage of Canadians Not Meeting Vitamin D cut-offs (2007-09)
Deficiency (<30 nmol/L) (leading to rickets in children & osteomalacia in adults)
5.4% of Canadians year around (94.5% are not vitamin D deficient )
Insufficiency (<50 nmol/L) (Inadequate for bone & overall health)
25.7% Canadians year around
Adequate (≥50 nmol) (adequate for bone and overall health)
74.3% Canadians year around
Canadian Health Measures Survey, 2007-09
Whiting et al., AJCN 2011:94, 128-35
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Risk of vitamin D deficiency (<30 nmol/L)
Greater risks with winter & darker skin pigmentation
% a
t ri
sk
Summer month data for whites not available
Whiting et al. AJCN 2011
CHMS, 2007-09
(all racial groups
other than Caucasians)
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Risk of inadequacy –Plasma Vitamin D <50 nmol/L
25.7% of Canadians year around
31.0% in winter, 22.4% in summer
Males 28.7%, females 22.8% (p<0.05)
Non-whites 51.4%, whites 19.9% (p<0.05)
(Inadequate for bone and overall health)
Whiting SJ et al. AJCN 2011, 94, 128-135
CHMS 2007-09
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Risk of vitamin D inadequacy (<50 nmol/L)
1) Increasing risk with darker skin pigmentation for all age groups.
2) The youngest and oldest Canadians have the highest levels of vitamin D
Whiting et al. AJCN 2011
(CHMS 2007-09)
% a
t ri
sk o
f in
ad
eq
uacy
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Vitamin D supplement use among Canadians
31% reported taking a vitamin D supplement
Whites 32%, Non-whites 28%
69% took less than 400 IU
3% took greater than 1000 IU
(Canadian Health Measures Survey, 2007-09)
Whiting SJ et al. AJCN 2011, 94, 128-135
CHMS 2007-09
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Supplement use and plasma Vitamin D below 50 nmol/L
by season and race shows increasing risk of inadequacy
with lack of supplement use, winter collection and darker
skin pigmentation
% a
t ri
sk o
f in
ad
eq
uacy (
<50 n
mo
l/L
)
Whiting et al AJCN 2011
(CHMS 2007-09)
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Conclusions
26% of Canadians have Vitamin D level below the level associated with adequacy for bone & overall health. 5% are deficient in vitamin D (rickets & osteomalacia)
The youngest and oldest Canadians have the highest level of plasma vitamin D
White (vs non-white) racial background and sunlight exposure are associated with higher plasma vitamin D levels
In winter, 1/3 of Canadians not taking supplements had <50 nmol/L, for no-whites, almost 2/3 had levels <50 nmol/L
Supplement use is associated with half the prevalence of insufficient levels, particularly useful for nonwhites
While 74% of Canadians achieved sufficient levels, for many Canadians, current food choices do not appear to be sufficient to attain plasma vitamin D levels of 50 nmol/L, especially in winter.
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Fish Omega-3 Fatty Acids and Health
Fish omega-3 fatty acids (EPA and DHA) reduce the risk of cardiovascular disease, heart disease, hypertension and stroke.
Possibly reduce cancer risk and diabetes
In infants, DHA required for optimum development of brain and retina in infants.
Some infant formulas are fortified with EPA and DHA
For overall health, intake of two servings of fatty fish (salmon, mackerel, sardines etc.) or 500 mg of EPA + DHA are recommended
Omega-3 index (% EPA +DHA in red blood cell total fat) is a biomarker of omega-3 status. Omega-3 Index ≤4 associated with high risk, 4 to 8 moderate risk, ≥8 low risk for CHD.
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Health Canada Study (2012-13)
Heart disease, diabetes and hypertension are more common in South Asian Canadians than White Canadians.
Goal: To determine whether there is an association between Vitamin D, Omega-3 status with blood biomakers of heart disease (cholesterol profile, TG, sugar, and many novel biomarkers )
Variation with season (winter & summer), skin colour and intake levels
Study will provide baseline data for South Asians and White Canadians
Results useful to Health Canada make inform decisions on dietary recommendations on vitamin D and omega-3 fatty acids for South Asian Canadians
Participants will be provided their results
Blood clinics in April and September, 2012
Vitamin D, Omega-3 and Cholesterol Status of
South Asian & White Canadians
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DR. NIMAL RATNAYAKE
NUTRITION RESEARCH DIVISION
FOOD DIRECTORATE
HEALTH CANADA
TEL: 613-954-1396
For more information and for participating in the study
contact:
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National consumption data for the General
USA Population
Canadian vitamin D intakes Vatanparast et al. 2010 using Canadian Community Health Survey Cycle 2.2 2004
200 IU
300 IU
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