VITAMIN D UPDATE Vitamin D as a nutrient

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1 VITAMIN D UPDATE Vitamin D as a nutrient Professor Susan J Whiting College of Pharmacy and Nutrition University of Saskatchewan CANADA

2 Vitamin D as a Nutrient Why sun exposure is not adequate for UK or Canada Dietary vitamin D sources currently not adequate Natural sources Fortification Bio Addition Supplements Getting governments to action on vitamin D

3 Whiting et al., 2008 Vitamin D Has Two Pathways Endocrine and Paracrine/Authocrine

4 Ensuring Adequate Vitamin D As indicated on the previous slide, vitamin D may be obtained from: Skin synthesis Diet Enough must be obtained that results in levels of 25OHD above 50 nmol/l This level satisfies Institute of Medicine (IOM) recommendations Others feel levels should be higher, for paracrine/autocrine functions

5 IOM Recommendations RDAs Healthy people to maintain 25(OH)D at 50 nmol/l 0-1 y 1-70 y 71+ y 400 IU (10 μg) 600 IU (15 μg) 800 IU (20 μg) Endocrine Society At risk people to maintain 25(OH)D at 75 nmol/l 0-1 y 1-18 y 18+ y IU IU IU 5

6 Maintaining 25(OH)D levels Sun exposure algorithm 100 % full body exposure for 1 MED = 20,000 IU 25 % body exposure for 1/4 MED = 1000 IU (25% is ~ arms and legs exposed) MED = minimal erythemal dose Webb & Engelsen, 2006

7 Times For ¼ Minimal Erythemal Dose (MED) that provides 1000 IU if 25% of skin is exposed Skin Type [Fitzgerald] Time (minutes) at noon June 21 At 42.5 ºN Time (minutes) at noon June 21 At 62.5 ºN I - Burns easily 4 7 II - Mostly burns 6 9 III - Mostly tans 8 11 IV - Mediterranean V - East Asian VI - African Webb & Engelsen 2006: NOTE: cloudless day

8 Decline in previtamin D3 synthesis in skin with age Godar et al., Dermato-Endocrinology 3:4, ; October/November/December 2011

9 Sun Messaging for Vitamin D is a Complex Message According to previous 2 slides, there are at least 5 factors to consider for ensuring adequate synthesis of vitamin D: Month of the year [no synthesis in winter] Time of day [only when sun is > 45 ] Latitude [determines length of winter] Skin type [skin melatin is a natural sunscreen] Age (older age makes synthesis difficult)

10 Effect of season on mean serum 25(OH)D concentrations by ethnicity in Canada Those not European Have less 25OHD at end of summer Drop in 25OHD levels not prevented by Canadian diet of IU Gozdzik et al., 2010

11 Dietary Sources of Vitamin D 1) Naturally Occurring fish, meat Few products guide consumers to what fish provide vitamin D naturally Only oily ocean varieties

12 Dietary Sources of Vitamin D 2) Fortified in Canada at 5 μg/l food vehicles include milk, soy milk, margarine, juice In USA: milk, cheese, bread, yogurt, breakfast cereals, juice, margarine.

13 Food sources of vitamin D, Canadian children 1 8 years Vitamin D intake (µg/day) Food sources of vitamin D, Canadians > 8 y Males Females Milk products Meat & Alt. Other foods Grain products Vegetables & fruit Vatanparast et al.

14 Role of fortified milk on Vitamin D status Canadian pop n Winter levels of 25(OH)D as nmol/l However, higher SES of milk drinkers Also, white more likely to drink milk than nonwhite Langlois et al. 2010

15 Dietary Sources of Vitamin D 3) Bio additive sources, e.g., irradiated yeast, irradiated mushrooms [as in this soup], vitamin D added to animal feeds

16 Dietary Sources of Vitamin D 4) Supplements in Canada these are recommended for infants and for older adults in 2007 => 400 IU infants & 400 IU older adults (> 50y) In Canada, no product may be over 1000 IU

17 Effect of Supplement Use on Prevalence Below 50 nmol/l by Race and Season: CHMS National survey, , age 6 to 79 years 70 % Total Total users Total no use Winter All Winter users Winter no use Winter Other Winter Other users Winter Other no use 0 All Whiting et al., AJCN 2011

18 What is the concern about risks? There is a need for supplements in absence of adequate sun exposure and/or dietary intakes Yet some may feel there are risks to using vitamin D supplements For almost all nutrients, too little poses risk of deficiency; too much pose risks of excess We need to manage the expected U shape relationship in which RDA is minimum for reducing risk of deficiency and UL is point of no risk for excess

19 Dietary Reference Intakes Paradigm is U shape Recommended Intake Excessive Intake Safe Range of Intake Adapted from Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, Food and Nutrition Board, Institute of Medicine, National Academy of Sciences, 2001

20 Safety of Vitamin D There is a revised (2011)UL for vitamin D in USA/Canada By definition a UL is safe For repletion, intakes above the UL are required and necessary Age 1 3 y: 62.5µg (2500 IU) Age 4 8 y: 75 µg (3000 IU) Age 9 + y: 100 µg (4000 IU) 20

21 How Do We Advocate for D? Emphasize lack of sun exposure due to new factors preventing adequate vitamin D skin synthesis Low % skin surface, skin pigmentation, sun cream use Dietary vit. D dependent on oily fish consumption But discourage use of cod liver oil (Cannell et al., 2008) Vitamin D from synthesis or diet must meet needs: Intakes must meet what used to be obtained with sun exposure Fortification to overcome lack of skin synthesis is similar to iodized salt to overcome lack of soil iodine Supplements need to be promoted to everyone Barriers to use include cost, health provider encouragement

22 References Cannell J, H.et al. (2008). Cod liver oil, vitamin A toxicity, frequent respiratory infections and the vitamin D deficiency epidemic (Editorial) Annals of Otology, Rhinology & Laryngology 117: Godar et al., Dermato Endocrinology 3:4, ; October/November/December 2011 Gozdzik A. et al. (2010) Seasonal fluctuations in vitamin D levels in healthy young adults of diverse ancestry living in Toronto. Journal of Nutrition 140(12): Langlois K, et al.. (2010) Vitamin D status of Canadians as measured by plasma 25 hydroxy vitamin D levels in the Canadian Community Health Survey. Health Reports. 21: Vatanparast H. et al. (2010) Despite Mandatory Fortification of Staple Foods, Vitamin D Intakes of Canadian Children and Adults are Inadequate. J Steroid Biochemistry and Molecular Biology. 121: Webb, A.R. and Engelsen, O.(2006). Calculated ultraviolet exposure levels for a healthy vitamin D status. Photochem.Photobiol. 82, Whiting S, et al. (2011) Vitamin D status of Canadians as measured by plasma 25 hydroxy vitamin D levels in the Canadian Community Health Survey. American Journal of Clinical Nutrition. 94: Whiting, SJ, et al. (2008) Current Understanding of Vitamin D Metabolism, Nutritional Status and Role in Disease Prevention, in Coulston A & Carol J. Boushey Nutrition in the Prevention & Treatment of Disease 2nd Edition. Elsevier, Inc. Chapter 43.