Rickets has been in the news lately, especially in association with breastfeeding. Before digging into those reports, let's cover the basics:
The Nelson Textbook of Pediatrics says
"Rickets is the term signifying a failure in mineralization of growing bone or osteoid tissue....During the first third of this century, the predominant cause of rickets was nutritional deficiency of vitamin D due either to inadequate direct exposure to ultraviolet rays in sunlight (296-310 nm; these rays do not pass through ordinary window glass) or to inadequate intake of vitamin D, or both. Vitamin D deficiency rickets is rare among infants and children in the industrialized countries. Deficiency may occur in unsupplemented dark-skinned infants or in breast-fed infants of mothers unexposed to sunlight." (p. 184)
Vitamin D does not itself deposit into bone, but it's a crucial part of the metabolic pathway that allows new bone cells to take up calcium and so harden ("mineralize"). Cow's milk and infant formula these days are routinely fortified with vitamin D. Previously, cod liver oil was one of the better sources, which accounts for it being given to children. The precursor of vitamin D is naturally available in human skin and automatically converted to vitamin D when the skin is exposed to sunlight, so you can do without the supplement if you're exposed to sunlight -- see, that stuff about getting out and playing in the fresh air is not just your mother trying to get rid of you.
There are other causes for rickets besides vitamin D deficiency, including celiac disease, cystic fibrosis, and various metabolic disorders, but the recent articles have been concerned only with vitamin D deficiency rickets.
Symptoms of rickets include a "Ping-Pong ball" feeling to the front of the skull, enlarged junctions between the rib bones and cartilege on the front of the chest (the "rachitic rosary"), swollen wrists and ankles, and bending of the long bones of the arms and legs. Of course, I am not a doctor and if you're reading this, you probably aren't either. This is not something you should try to diagnose or treat yourself, so if you're worried, bring it up at your next well-baby visit!
The current news about rickets comes from a study in the August Journal of Pediatrics. The actual article is titled "Nutritional rickets in African American breast-fed infants" (link to abstract; full text requires a paid subscription to the journal). The study covers 30 infants, all African American, over the course of a decade in North Carolina. The average duration of breastfeeding for these infants was 12.5 months. Their conclusion is
"Factors that may have contributed to the increase in referrals of children with nutritional rickets include more African American women breast-feeding, fewer infants receiving vitamin D supplements, and mothers and children exposed to less sunlight. We recommend that all dark-skinned breast-fed infants and children receive vitamin D supplementation."
An accompanying editorial suggests
"The reappearance of rickets may be an unintended consequence of an admirable health initiative: the promotion of human milk feeding. Currently, only about 15% of African American infants even begin this optimal feeding method. Only about a fifth of all American infants are still human milk–fed at 6 months of age. The Healthy People 2000 initiative has set a target of 75% of American infants breast-feeding for at least 6 months. If this goal is to be achieved, a major effort to increase the frequency and duration of breast-feeding among African Americans will be required. Strategies to effect this have been reported. Unless this change is accompanied by provision of vitamin D supplementation to replace that currently derived from formula, an epidemic of rickets seems inevitable."
The editorial goes on to recommend universal administration of vitamin D supplements to breastfed infants:
"We do not believe that additional research is required to support a practice that nearly a century of experience has shown to be safe, cheap, and effective. The suggestion that supplementation be restricted to the offspring of actually or potentially deficient mothers is doubly flawed. The cost of a single assay of 25-hydroxy-calciferol, the best objective measure of vitamin D sufficiency, is prohibitive. In any case, maternal vitamin D stores influence calcium metabolism in infants only briefly during the neonatal period. Basing supplementation advice on the complexion of the mother or her infant would be impossible to incorporate into a usable practice guideline. Similarly, the prescription of regular sun exposure is not only difficult to quantitate but also may be in conflict with other current health recommendations. The protocol of Eliot in the early 1920s, for example, called for sufficient sunlight to induce reddening, hardly appropriate advice today.
"It is difficult to understand the origin of the apparent objection to vitamin D supplementation of nursing infants. One factor may be the way in which it is available. Most supplements used today are in the form of drops containing vitamins A and C, as well as calciferol. Such preparations date from the days of evaporated milk formulas and have no rationale today, as human milk is an adequate source of these vitamins. The additional amounts so given are superfluous but harmless.
"A second objection may actually derive from our very appropriate advocacy for human milk as a “perfect food.” For some, the need for supplementation may imply nutritional inadequacy. As emphasized above, however, calciferol is in no sense a nutrient, but rather the precursor of a steroid hormone that is not naturally present in any infant food. Classifying the antirachitic substance in cod liver oil as a vitamin was an unfortunate historical error that has become too ingrained to correct. If one views calciferol in this light, then it is not necessary to consider human milk “deficient.” Instead, the provision of supplemental calciferol can be looked on as ensuring an adequate substrate for a hormone whose normal production has been adversely affected by the realities of modern living conditions. Human milk is, indeed, the “perfect food” for infants. Unfortunately, neither it nor any unsupplemented food or formula can prevent climate, latitude, smog, economic factors, or religious practices from coming between infants and sunshine."
It's the message from this editorial, not the details of the underlying study, that are being emphasized in such secondary reports as those on HealthScout and MedScape.
First off, this isn't a new problem, despite this year's flurry of publicity. A quick search of the online archives of Pediatrics magazine (available to subscribers only, so I won't hyperlink individual articles) turned up articles as far back as 1957 dealing with this exact problem. For example, here's a chunk of the abstract from "An outbreak of vitamin D deficiency rickets in a susceptible population" (Pediatrics 1979 64: 871-877):
"Nutritional, racial, cultural, and environmental factors have combined to produce a resurgence of vitamin D deficiency rickets in urban Philadelphia. Between January 1974 and June 1978, 24 cases were diagnosed at the Children's Hospital of Philadelphia. Patients' ages ranged from 4 to 58 months. Presenting complaints included seizures, swollen wrists, pathologic fractures, and developmental regression. Sixteen patients were below the third percentile for length and weight. Laboratory results indicated vitamin D deficiency in nursing mothers as well as in infants. All infants had been breast-fed and all were black. Ingestion of vitamin D was limited by exclusion of meat and/or dairy products in 21, and no infants had consistently taken supplemental vitamins. Nineteen were members of Muslim or Seventh Day Adventist faiths. Endogenous synthesis of vitamin D was limited by dark skin, by dressing in long garments with hoods and veils, and by air pollution in a densely populated northern city. The return to a more "natural" diet, free of food additives, has been accompanied by the return of a classic disease of industrial society."
Other articles in the Pediatrics archive cite fad diets and vegan diets as being risk factors for infants. And clear back in 1949 an article titled "Rickets in newborn infants; Clinical and histologic study" noted the association between exclusive breastfeedfing and rickets:
"A previous paper established that if premature infants are reared exclusively on human milk the content of calcium and inorganic phosphorus in their serum falls..."
The AAP Pediatric Nutrition Handbook says simply:
"There is little biologically active vitamin D in human milk. Therefore, dark-skinned infants will need a vitamin D supplement particularly if they are exposed to minimum amounts of sunlight."
Even though the editors of Journal of Pediatrics recommend universal vitamin D supplements, this is far from being the united advice of the childcare community.
The current American Academy of Pediatrics policy statement on breastfeeding says
"In the first 6 months, water, juice, and other foods are generally unnecessary for breastfed infants. Vitamin D and iron may need to be given before 6 months of age in selected groups of infants (vitamin D for infants whose mothers are vitamin D-deficient or those infants not exposed to adequate sunlight; iron for those who have low iron stores or anemia)."
The Canadian Paediatric Society takes a middle ground, recommending supplements but offering advice on using sunlight. Note that Canada has problems with communities in the far north where there are months with little sunlight:
"Vitamin D supplements (10µg/d or 400 IU/d) are recommended for all full-term infants who are breastfed. Supplements should continue until the baby's diet provides a source of vitamin D. For infants living in northern communities, 20µg/d (800 IU/d) of vitamin D is recommended....
"We don't know exactly how much time in the sun is enough. Depending on how sensitive a baby's skin is, 5 to 30 minutes a day should be sufficient. Babies should not be exposed to the sun between the hours of 10 a.m. and 2 p.m.
"Covering a baby's skin with protective clothing, or using sunscreen, is also recommended but it won't allow natural vitamin D to be formed. (Parents should not apply sunscreen to babies six months of age and younger as they may ingest the lotion.) There are periods of time during the winter, depending on where you live, when sunlight won't encourage vitamin D to be formed. That's because the sunlight won't contain the ultraviolet rays that are needed for the production of vitamin D."
As one might expect, La Leche League suggests that supplements are seldom needed:
"Research suggests that people of color, especially religious or cultural groups who wear enveloping clothing should expose their babies' uncovered cheeks to sunlight for just 20 minutes a day to get the needed vitamin D. In cases where this is not possible or the mother is not getting adequate vitamin D, doctors may prescribe a vitamin D supplement for the baby. According to La Leche League International, the world's recognized authority on breastfeeding, rickets has rarely been found in fully breastfed infants. This is true even in northern climates where there is less exposure to sunlight, which activates the formation of vitamin D. Research has shown that human milk contains adequate vitamin D for at least the first 6 months of life."
Unfortunately, this is from a press release that doesn't give any sources for the "research".
INFACT Canada also comes out against supplements, in a well-written review of the medical evidence subtitled "Breastfeeding in the park assures adequate vitamin D":
"In response to the controversial recommendation that all breastfed infants be supplemented with oral forms of vitamin D and not just those considered at "risk", we say this is unnecessary. Long term risks of artificial topping up the vitamin D levels for the majority of infants, where no risk and no cases have been reported may in fact do as yet undetermined harm."
In April 2001, Pediatrics published an article in their electronic version, "Severe Nutritional Deficiencies in Toddlers Resulting From Health Food Milk Alternatives", that reports on an unusual risk group for rickets and other dietary deficiency diseases: children of well-educated parents who wean their children from breastmilk to soy milk. Of course soy milk is not fortified with Vitamin D, and in one child who was not exposed to much sun, the result was a severe case of rickets.
An accompanying commentary reports 5 more cases of rickets in Georgia between January 1997 and June 1999. "All 5 additional vitamin D-deficient rickets cases were breastfed black male children who did not receive vitamin D supplements while breastfeeding. Several of the children shared other common risk factors for the development of vitamin D-deficient rickets, including inadequate sunlight exposure and breastfeeding >6 months without any dietary or supplemental source of vitamin D." In addition, since the review was based on hospitalizations only, the authors feel they certainly missed cases that were treated on an outpatient basis. The authors give a good review of what we know about the risk factors for rickets:
"Inadequate sunlight exposure is the most important factor associated with the development of vitamin D-deficient rickets. In humans the main source of vitamin D comes from the ultraviolet light (290-320 nm) photo conversion of 7-dehydrocholesterol in the skin to previtamin D3, which thermally isomerises to cholecalciferol (vitamin D3). Serum vitamin D concentrations vary with the amount of sunlight exposure a person receives, and dietary or supplemental sources of vitamin D are thought to be necessary if sunlight exposure is not adequate.
"Defining how much sun exposure is needed to prevent rickets is difficult because the amount of ultraviolet light that penetrates the skin is affected by a number of factors, including air pollution, latitude, time of day, amount of body surface covered by clothing, amount of cloud cover, and degree of skin pigmentation. In addition, sunscreens that block ultraviolet radiation needed for photosynthesis of vitamin D may impede the photosynthesis of vitamin D in the skin. Although white infants need 30 to 120 minutes per week of sunlight exposure, depending on clothing coverage, no accurate estimates of adequate sunlight exposure exist for infants with darker skin complexion; however, their requirement will be greater because melanin competes with 7-dehydrocholesterol for ultraviolet radiation photons....
"Infants of vitamin D-deficient mothers also are at increased risk for rickets because the vitamin D stores of the newborn depend entirely on the vitamin D stores of the mother. If the mother is vitamin D-deficient, the infant will be deficient because of decreased maternal-fetal transfer of vitamin D. Vitamin D supplementation for vitamin D-deficient pregnant women improves the infant's birth weight and subsequent linear growth. ...
"Infants who have inadequate sunlight exposure or who have poor stores of vitamin D at birth need adequate dietary or supplemental sources of vitamin D to prevent vitamin D-deficient rickets. The recommended daily intake of vitamin D for infants and children is 200 IU vitamin D per day. Few foods naturally contain vitamin D, and those that do, such as egg yolks, fish liver oils (eg, cod liver oil), fatty fish (eg, salmon, herring, mackerel, and sardines), shrimp, and chicken liver, are not typically found in infant or toddler diets. Other food items such as vitamin D-fortified cow's milk (400 IU vitamin D/L) and breakfast cereals (40-100 IU/1 cup), and commercial infant formulas (400 IU/L) contain vitamin D only because they are fortified. Infant cereals, cheese, and most commercial yogurts typically are not fortified with vitamin D. The vitamin D content of breast milk is low (12-60 IU/L) even with adequate maternal vitamin D intake. Breastfed infants with no supplemental source of vitamin D and with limited sunlight exposure are at greater risk for developing vitamin D-deficient rickets. Prolonged breastfeeding without sufficient dietary or supplementary sources of vitamin D may have contributed to the development of rickets in our cases"
The authors suggest that universal vitamin D supplementation of breastfed infants, while controversial, might be prudent.
Remember, I am not a physician and my infant is not your infant! That said, my reading of the evidence is that our baby is at extremely low risk for vitamin D deficiency rickets as a consequence of exclusive breastfeeding. The studies that I have found identify certain populations of infants at high risk:
Our baby does not fall into either of these risk classes. We also live on a farm in a sunny climate and Adam is going to end up spending a lot of time outside.
It's interesting to speculate why the editors of Journal of Pediatrics felt it necessary to take results from one small population and use them to justify recommendations made to all parents regardless of situation. Did they find it too politically incorrect to say straight out that this is a problem for African American babies in northern climates, despite the title of the study they rely on? Are they so caught up in an interventionist model of care that they discount completely the possibility of educating a target population who, I suspect, they view as illiterate or underliterate? Or did they just have a bad day arguing with their local LLLI leaders for some reason? I don't know, but the connection between the study and the recommendation appears mighty tenuous to me.
The American Academy of Pediatrics has recently reviewed the evidence and changed their guidelines on Vitamin D supplementation. They note that the CDC, American Cancer Society, and the AAP are united in a new campaign to try to cut the risk of skin cancer by cutting exposure to direct sun:
"Thus, guidelines for decreasing exposure include directives from the AAP that infants younger than 6 months should be kept out of direct sunlight, children’s activities that minimize sunlight exposure should be selected, and protective clothing as well as sunscreens should be used."
They go on to say:
"Infants who are breastfed but do not receive supplemental vitamin D or adequate sunlight exposure are at increased risk of developing vitamin D deficiency or rickets. Human milk typically contains a vitamin D concentration of 25 IU/L or less. Thus, the recommended adequate intake of vitamin D cannot be met with human milk as the sole source of vitamin D for the breastfeeding infant."
And the recommendation is:
To prevent rickets and vitamin D deficiency in healthy infants and children and acknowledging that adequate sunlight exposure is difficult to determine, we reaffirm the adequate intake of 200 IU per day of vitamin D by the National Academy of Sciences and recommend a supplement of 200 IU per day for the following:
The official recommendation is that the supplementation begin during the first two months of life.