Susan Burger wrote: "Third, a piece I irresponsibly left out is that there is no vitamin D conversion from sunlight in Boston from October to March!!!!! I don't know about other latitudes. We're not that far south here in Manhattan and have lots of tall buildings, pollution, a cold snap that has us bundled up, so this has me concerned."
Yes, latitude plays a role in vitamin D status. Research in Boston (42° N) shows no vitamin D synthesis from *November to February.* Many other factors are also involved, as I explain in my article "Sunlight Deficiency: A Review of the Literature" (Good Mojab 2003):
"Anyone with inadequate exposure to UVB radiation in sunlight is at risk for vitamin D deficiency. Risk factors for nurslings and their mothers overlap and interact, and include indoor confinement during the day (e.g., due to exclusively indoor daycare, unsafe neighborhoods, custom),39 living at higher latitudes (e.g., essentially no vitamin D is produced with sun exposure from November to February in Boston [42° N] and from mid-October to mid-April in Edmonton, Canada [52º N]),40, 41 darker skin pigmentation,42-45 living in urban areas with pollution and/or buildings that block sunlight,46-48 sunscreen use,49-51 seasonal variations resulting in less ultraviolet radiation (e.g., late winter and early spring in the northern hemisphere),52, 53 covering much or all of the body when outside (e.g., due to custom, fear of skin cancer, cold climate),54-57 increased birth order (e.g., a mother's sixth child has a higher risk of vitamin D deficiency than does her first child),58, 59 the replacement of human milk with foods low in calcium,60-64 the replacement of human milk with foods that reduce calcium absorption (e.g., grains and some green leaves containing phylates, oxalates, tannates, and phosphates; cereals grown in soil high in strontium),65-67 and exposure to lead (due to lead's inhibition of vitamin D synthesis).68, 69"
Susan Burger also wrote: "This is a tough issue with many aspects and I've been having a hard time getting a good grasp of all the details."
You are in good company. Sunlight deficiency is a very tough issue--probably the toughest topic I have ever worked on. So many disciplines are involved (and no single person can be an expert in all of them): endocrinology, epidemiology, culture, skin cancer, ethics, informed consent, public health, poverty, racism, psychology, the environment, breastfeeding and lactation, etc. I have worked for a few years now on sunlight deficiency, trying to pull pieces together from these diverse disciplines, and I am still routinely challenged by the complexity, controversy, and global relevance of it all. It is very clear that vitamin D supplements are a highly effective tool for preventing vitamin D deficiency in exclusively breastfed infants at risk of sunlight deficiency. I also don't think the conversation should stop there. I am disturbed by the connection of the formula industry to the pharmaceutical industry (e.g., a formula company makes Tri-Vi-Sol in the US and makes D-Vi-Sol in Canada) and by the lack of an over-the-counter vitamin D only supplement in the US. I am disturbed by the lack of research on the effects of vitamin D supplementation on the infant gut and on breastfeeding beliefs and behaviors. I'm disturbed by the exposure of so many breastfeeding mothers to formula advertising via the packaging of vitamin supplements. I am disturbed by a culture and health care system that make it much easier for health care providers to recommend supplements for all exclusively breastfed babies than to help mothers engage in time-consuming informed decision making based on individual circumstances. I am disturbed by short-sighted public health policies that create several public health problems while trying to solve one (e.g., recommending avoidance of all sun exposure and increasing the risk of vitamin D deficiency [and a host of other diseases] by doing so.) Vitamin D deficiency increases the risk of or risk of death from many diseases (a geographic distribution of some of these diseases is sometimes seen reflecting, most likely, how latitude effects the availability of UVB in sunlight): myopathy, infections, inflammatory and autoimmune diseases, hypertension, cardiovascular diseases, diabetes mellitus, and cancer (prostate, breast, and colon) (Zittermann 2003). I am disturbed by brochures related to preventing skin cancer that make no mention whatsoever about the many risks of avoiding sun exposure. I have yet to see a brochure that warns people of the need to ingest adequate vitamin D via consuming fortified foods or taking a vitamin D supplement if they follow the brochure's recommendations. (If anyone finds one, please let me know.) I am disturbed by our relatively poor understanding of how much vitamin D is actually needed by humans not just to prevent bone disease, but to maintain biologically normal functioning and health in a variety of organ systems. Some cells with evidence for vitamin D receptors include: intestinal cells; muscle cells; osteoblasts; distal renal cells; parathyroid cells; islet cells, pancreas; epidermal cells; circulating monocytes; transformed B-cells; activated T-cells; neurons; placenta; skin fibroblasts; chondrocytes; colon enterocytes; liver cells; prostate cells; ovarian cells; keratinocytes, skin; endocrine cells, stomach; aortic endothelial cells; and pituitary cells (Zittermann 2003). Keeping my presentation on sunlight deficiency, vitamin D and the breastfed baby up to date is an ongoing and challenging task. Trying to talk about sunlight deficiency in an hour or hour-and-a-half nutshell is mentally exhausting. Always, always, conference participants ask me very intelligent questions that I don't know the answer to, that no one knows the answer to, because the research has not yet been conducted.
I think that an important part of helping mothers make informed decisions (and thereby fulfilling the ethics of my profession) includes letting them know how complex this topic is--that we don't have all the answers. I just can't ethically give simple one-size-fits-all answers. A person's individual risk is the result of the interaction of multiple factors in the list above. I believe mothers are in the best position to evaluate the risk factors in their situation if they are only given the opportunity to do so.
References:
Good Mojab, C. Sunlight deficiency: A review of the literature. Mothering March-April 2003; 117:52-55; 57-63. (see the publications or sunlight deficiency page of my website to read this article in full).
Zittermann, A.Vitamin D in preventive medicine: are we ignoring the evidence? Br J Nutr. 2003 May; 89(5): 552-72
Additional reading (see the publications or sunlight deficiency page of my website to read these articles in full).:
Good Mojab, C. Sunlight deficiency: Helping breastfeeding mothers find the facts. Leaven August-September 2003; 39(4):75-79.
Good Mojab, C. Sunlight deficiency and breastfeeding. Breastfeeding Abstracts 2002; 22(1):3-4.
With apologies for the length of this post,
Cynthia
Cynthia Good Mojab, MS clinical psychology, IBCLC, RLC
Ammawell
Website: http://home.comcast.net/~ammawell
Email: [log in to unmask]
Announcement only email list: [log in to unmask]
***********************************************
To temporarily stop your subscription: set lactnet nomail
To start it again: set lactnet mail (or digest)
To unsubscribe: unsubscribe lactnet
All commands go to [log in to unmask]
The LACTNET mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software together with L-Soft's LSMTP(R)
mailer for lightning fast mail delivery. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
|
