Potential Health Benefits of Vitamin D and Omega-3 Fatty Acids

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1 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

2 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. 2

3 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. 3

4 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-17 th century in Briton. In the late 19 th and 20 th 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). 4

5 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. 5

6 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. 6

7 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. 7

8 Vitamin D Status Serum concentration of 25-hydroxy Vitamin D (25(OH) D is the best indicator of Vitamin D status 8

9 Serum vitamin D concentration & Health Serum Vit. D (nmol/l) Health Status <30 Vitamin D deficiency, rickets in children & osteomalacia in adults Inadequate for bone & overall health in healthy individuals 50 Adequate for bone & overall health in healthy individuals >125 Potential adverse effects (The levels identified by the US institute of medicine in its extensive review of literature) Ref. US Institute of Medicine (2011) 9

10 Recommended Daily Dietary intake for Vitamin D Intake levels recommended for maintaining a serum vitamin D concentration of >50 nmol/l (adequate for bone & overall health in healthy individuals Age Male Female Pregnancy Lactation 0-12 months 400 IU (10 mcg) 1-13 years 600 IU (15 mcg) years 600 IU (15 mcg) years 600 IU (15 mcg) > 70 years 800 IU (20 mcg) 400 IU (10 mcg) 600 IU (15 mcg) 600 IU (15 mcg) 600 IU (15 mcg) 800 IU (20 mcg) 600 IU (15 mcg) Ref. US Institute of Medicine, IU (15 mcg) 10

11 Sources of vitamin D Foods Foods fortified with vitamin D Supplements Sunlight (ultraviolet (uv) B radiation) 11

12 Sources of vitamin D: Food Food IUs per serving Percent Daily Value Cod liver oil, 1 tablespoon Salmon, cooked, 3 ounces Tuna, canned in water, 3 ounces Liver, beef, cooked, 3 ounces Egg, 1 large (Vit D found in yolk) 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. 12

13 Sources of vitamin D: Foods Fortified With Vitamin D Food IUs per serving Percent Daily Value Orange juice, fortified with Vit D Milk, whole, vit D fortified, 1 cup Yogurt, vit D fortified, 6 ounces Margarine, fortified, 1 table spoon Cereal, fortified with vit D Orange juice, milk, yogurt, margarine, and many other foods contain added Vit D. 13

14 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 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 wholebody, 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. 14

15 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. 15

16 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. 16

17 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. 17

18 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. 18

19 Plasma vitamin D (n mol/l) National data on vitamin D Status in the Canadian Health Measures Survey (n=5306) Mean plasma vitamin D levels of Canadians, Adequate level for overall health Age group (years) Whiting et al. AJCN 2011:94,

20 Percentage of Canadians Not Meeting Vitamin D cut-offs ( ) 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, Whiting et al., AJCN 2011:94,

21 % at risk Risk of vitamin D deficiency (<30 nmol/l) Greater risks with winter & darker skin pigmentation (all racial groups other than Caucasians) Summer month data for whites not available Whiting et al. AJCN 2011 CHMS,

22 Risk of inadequacy Plasma Vitamin D <50 nmol/l (Inadequate for bone and overall health) 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) Whiting SJ et al. AJCN 2011, 94, CHMS

23 % at risk of inadequacy 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 ) 23

24 Vitamin D supplement use among Canadians (Canadian Health Measures Survey, ) 31% reported taking a vitamin D supplement Whites 32%, Non-whites 28% 69% took less than 400 IU 3% took greater than 1000 IU Whiting SJ et al. AJCN 2011, 94, CHMS

25 % at risk of inadequacy (<50 nmol/l) 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 Whiting et al AJCN 2011 (CHMS ) 25

26 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. 26

27 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. 27

28 Health Canada Study ( ) Vitamin D, Omega-3 and Cholesterol Status of South Asian & White Canadians 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,

29 For more information and for participating in the study contact: DR. NIMAL RATNAYAKE NUTRITION RESEARCH DIVISION FOOD DIRECTORATE HEALTH CANADA TEL:

30 Canadian vitamin D intakes Vatanparast et al using Canadian Community Health Survey Cycle National consumption data for the General USA Population 300 IU 200 IU 30

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