Phytic acid and nutritional rickets in immigrants

The Problem of Vitamin D Scarcity: Cultural and Genetic Solutions by Indigenous Arctic and Tropical Peoples

Vitamin D metabolism differs among human populations because our species has adapted to different natural and cultural environments. Two environments are particularly difficult for the production of vitamin D by the skin: the Arctic, where the skin receives little solar UVB over the year; and the Tropics, where the skin is highly melanized and blocks UVB. In both cases, natural selection has favored the survival of those individuals who use vitamin D more efficiently or have some kind of workaround that ensures sufficient uptake of calcium and other essential minerals from food passing through the intestines. Vitamin D scarcity has either cultural or genetic solutions. Cultural solutions include consumption of meat in a raw or boiled state and extended breastfeeding of children. Genetic solutions include higher uptake of calcium from the intestines, higher rate of conversion of vitamin D to its most active form, stronger binding of vitamin D to carrier proteins in the bloodstream, and greater use of alternative metabolic pathways for calcium uptake. Because their bodies use vitamin D more sparingly, indigenous Arctic and Tropical peoples can be misdiagnosed with vitamin D deficiency and wrongly prescribed dietary supplements that may push their vitamin D level over the threshold of toxicity.

Nutritional rickets around the world: an update

Worldwide, nutritional rickets continues to be an evolving problem with several causes. This paper provides an updated literature review characterising the prevalence, aetiology, pathophysiology and treatment of nutritional rickets worldwide. A systematic review of articles on nutritional rickets from various geographical regions was undertaken. For each region, key information was extracted, including prevalence, cause of rickets specific to the region, methods of confirming the diagnosis and current treatment and preventive measures. Calcium deficiency continues to be a major cause of rickets in Africa and Asia. Vitamin D deficiency rickets is perhaps increasing in the Americas, Europe and parts of the Middle East. There continues to be a distinct presentation of calcium-predominant versus vitamin D predominant rickets, although there are overlapping features. More careful diagnosis of rickets and reporting of 25-OHD concentrations has improved accurate knowledge of rickets prevalence and better delineated the cause. Nutritional rickets continues to be an evolving and multi-factorial problem worldwide. It is on a spectrum, ranging from isolated vitamin D deficiency to isolated calcium deficiency. Specific areas which require emphasis include a consistent community approach to screening and diagnosis, vitamin D supplementation of infants and at-risk children, prevention of maternal vitamin D deficiency and the provision of calcium in areas with low calcium diets.

Proximal myopathy in lacto-vegetarian Asian patients responding to Vitamin D and calcium supplement therapy - two case reports and review of the literature

Introduction

Severe proximal myopathy can occasionally be the first presenting complaint of patients with osteomalacia. This may lead to investigations and misdiagnosis of a neuromuscular disease, rather than a metabolic bone disease.

Case presentations

We present here two cases of severe proximal myopathy in patients who were both of South Asian origin and lacto-vegetarians: a 31-year-old Indian man and a 34-year-old Indian woman. In both cases, their clinical symptoms fully resolved following vitamin D and calcium replacement therapy. These patients were at risk of osteomalacia due to their dietary intake and ethnicity. The role of dietary intake and sunlight exposure in the development of osteomalacia in certain ethnic groups living in Western Europe is reviewed here.

Conclusion

These two cases emphasize the importance of recognizing osteomalacia in at-risk individuals, as the condition is reversible and easily treated with vitamin D and calcium supplementation. It may also help avoid prolonged and unnecessary investigations of these patients.

Relationship of calcium absorption with 25(OH)D and calcium intake in children with rickets

Nutritional rickets has long been considered a disease caused by vitamin D deficiency, but recent data indicate that inadequate dietary calcium intake is an important cause of rickets, particularly in tropical countries. Children with rickets due to calcium deficiency do not have very low 25(OH)D concentrations, and serum 1,25(OH)(2) D values are markedly elevated. Studies of Nigerian children with rickets demonstrated they have high fractional calcium absorption. A high-phytate diet was demonstrated to increase calcium absorption compared with the fasting state, and enzymatic dephytinization did not significantly improve calcium absorption. When given vitamin D, children with rickets have a marked increase in 1,25(OH)(2) D concentrations without any change in fractional calcium absorption. No positive relationship was found between fractional calcium absorption and serum 25(OH)D concentrations in children on low-calcium diets. More research is needed to understand the interaction between calcium and vitamin D and the role of vitamin D in calcium absorption.

Does inadequate diet during childhood explain the higher high fracture rates in the Southern United States?

SUMMARY

Southern states have the highest age-adjusted hip fracture rates among older adults in the United States. Regional hip fracture rates in the United States in 1986-1993 correlate with death rates from rickets in the 1940s. Historical patterns of bone nutrition early in life might explain contemporary geographic patterns in bone fragility.

INTRODUCTION

State of residence early in life is a better predictor of the risk of hip fracture after age 65 than state of current residence. Therefore, the geography of rickets mortality in the United States before 1950 was compared with the geography of hip fracture rates among older adults in the United States during 1986-1993.

METHODS

Vital statistics data for the US white population for 1942-1948 allowed calculation of the ratio of deaths from rickets to live births for each geographic division of the USA. These ratios were correlated with previously published, standardized hip fracture rates among whites 65-89 years old during 1986-1993 by census division.

RESULTS

During 1942-1948, the rickets mortality ratio among whites was 3.11 in the South, 1.91 in the Northeast, 1.75 in the Midwest, and 1.04 in the West. The correlation of mortality with risk of hip fracture was 0.71 (p = 0.03) for both sexes combined and 0.86 (p = 0.01) for women.

CONCLUSIONS

Inadequate nutrition during skeletal formation early in life might explain the higher incidence of hip fracture among older adults in the South.

Vitamin d deficiency-a clinical spectrum: is there a symptomatic nonosteomalacic state?

Vitamin D deficiency is not uncommon even in the sunny land of India. Lack of sun exposure and inadequate oral intake are both responsible for vitamin D deficiency. This article provides a retrospective, examining the effects of Vitamin D deficiency in 71 patients. The study's inclusion criterion was low vitamin D level combined with musculoskeletal symptoms but without the presence of osteomalacia. All patients in this study were suspected to have vitamin D deficiency. The data were retrieved from the case-charts of patients seen between 1996 and 2001 at the rheumatology services of Hinduja Hospital, Mumbai, India. This study found no correlation between Vitamin D levels and symptoms, or between the severity of Vitamin D deficiency and the number of symptoms displayed. Subclinical vitamin D deficiency or preosteomalacic state was the term coined for individuals with vitamin D deficiency producing nonspecific musculoskeletal symptoms in the absence of clinical osteomalacia.

Vitamin D deficiency in early childhood: prevalent in the sunny South Pacific

Objective

To estimate the prevalence of and risk factors for vitamin D deficiency in young urban children in Auckland, New Zealand, where there is no routine vitamin D supplementation.

Design

A random sample of urban children. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D <27·5 nmol/l (<11 ng/ml). Logistic regression analysis was used to calculate odds ratios and, from these, relative risks (RR) and 95 % confidence intervals were estimated.

Setting

Auckland, New Zealand (36°52′S), where the daily vitamin D production by solar irradiation varies between summer and winter at least 10-fold.

Subjects

Children aged 6 to 23 months enrolled from 1999 to 2002.

Results

Vitamin D deficiency was present in forty-six of 353 (10 %; 95 % CI 7, 13 %). In a multivariate model there was an increased risk of vitamin D deficiency associated with measurement in winter or spring (RR = 7·24, 95 % CI 1·55, 23·58), Pacific ethnicity (RR = 7·60, 95 % CI 1·80, 20·11), not receiving any infant or follow-on formula (RR = 5·69, 95 % CI 2·66, 10·16), not currently receiving vitamin supplements (RR = 5·32, 95 % CI 2·04, 11·85) and living in a more crowded household (RR = 2·36, 95 % CI 1·04, 4·88).

Conclusions

Vitamin D deficiency is prevalent in early childhood in New Zealand. Prevalence varies with season and ethnicity. Dietary factors are important determinants of vitamin D status in this age group. Vitamin D supplementation should be considered as part of New Zealand’s child health policy.

Meals and dephytinization affect calcium and zinc absorption in Nigerian children with rickets

Nutritional rickets resulting from calcium insufficiency is common in Nigeria and high dietary phytate is thought to inhibit calcium and zinc absorption. We compared the effects of a high-phytate meal and enzymatic dephytinization on calcium and zinc absorption in Nigerian children with and without rickets. Nineteen children with rickets and 15 age-matched control children, aged 2-10 y, were given calcium (600 mg/d) and ergocalciferol (1250 microg/wk). After 6 wk, calcium and zinc absorption were measured in both groups with and without maize porridge using stable isotopes. One week later, absorption measurements were repeated to assess the effects of enzymatic dephytinization and fermentation of the maize porridge. The phytate concentration of maize porridge (3.87 +/- 0.38 g/kg wet weight) was reduced by enzymatic dephytinization (2.83 +/- 0.41 g/kg; P < 0.001) but not by fermentation (3.35 +/- 0.27 g/kg; P = 0.08). Calcium and zinc absorption were unaffected by the presence of rickets or by fermentation of maize porridge. Calcium absorption was greater with a meal (61.3 +/- 25.1%) than without (27.8 +/- 14.6%; P < 0.001). Zinc absorption was lower with a meal (16.2 +/- 8.0%) than without (63.4 +/- 23.9%; P < 0.001). Enzymatic dephytinization increased relative zinc absorption from a meal by 101 +/- 81% (P < 0.001) but did not affect calcium absorption. Rickets was not associated with impaired calcium or zinc absorption. Calcium absorption was enhanced by maize porridge, but zinc absorption was reduced. Enzymatic dephytinization increased zinc absorption. Multiple strategies may be required to optimize calcium and zinc absorption in deficient populations.

Meat consumption reduces the risk of nutritional rickets and osteomalacia

Endogenous vitamin D deficiency (low serum 25(OH)D3) is a necessary but insufficient requirement for the genesis of vitamin D-deficiency rickets and osteomalacia. The magnitude of the independent contributions of dietary factors to rachitic and osteomalacic risk remains uncertain. We reanalysed two weighed dietary surveys of sixty-two cases of rickets and osteomalacia and 113 normal women and children. The independent associations of four dietary variables (vitamin D, Ca, fibre and meat intakes) and daylight outdoor exposure with rachitic and osteomalacic relative risk were estimated by multivariate logistic regression. Meat and fibre intakes showed significant negative and positive associations respectively with rachitic and osteomalacic relative risk (RR; zero meat intake: RR 29·8 (95 % CI 4·96, 181), P<0·001; fibre intake: RR 1·53 (95 % CI 1·01, 2·32), P+0·043). The negative association of meat intakes with rachitic and osteomalacic relative risk was curvilinear; relative risk did not fall further at meat intakes above 60 g daily. Daylight outdoor exposure showed a significant negative association with combined relative risk (RR 0·33 (95 % CI 0·17, 0·66), P<0·001). Operation of the meat and fibre risk factors was related to sex, age and dietary pattern (omnivore/lactovegetarian), mainly determined by religious affiliation. The mechanism by which meat reduces rachitic and osteomalacic risk is uncertain and appears independent of revised estimates of meat vitamin D content. The meat content of the omnivore Western diet may explain its high degree of protection against nutritional rickets and osteomalacia from infancy to old age in the presence of endogenous vitamin D deficiency.

Coexisting Hyperthyroidism Abstract and Primary Hyperparathyroidism with Vitamin D-Deficient Osteomalacia in a Vietnamese Immigrant

OBJECTIVE

To present the first report of concurrent hyperthyroidism, primary hyperparathyroidism (PHP), and vitamin D-deficient osteomalacia.

METHODS

We describe the complicated clinical course in a 65-year-old Vietnamese immigrant, and underlying factors potentially contributing to her condition are discussed.

RESULTS

Our patient, who had hyperthyroidism and hypercalcemia, was found to have an inappropriately high level of intact parathyroid hormone (PTH) because of a parathyroid adenoma, detected on a parathyroid scan. With propranolol treatment, however, improvement was noted in both laboratory data--intact PTH, ionized calcium, serum total calcium, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and urinary cyclic adenosine monophosphate--and findings on ultrasonography and nuclear parathyroid scanning. Later, the adenoma was removed surgically. The improvement of PHP after administration of a beta-adrenergic blocker suggested that the parathyroid adenoma in this patient was not completely autonomous. The patient also had vitamin D-deficient osteomalacia that was confirmed by a low serum level of 25-hydroxyvitamin D3 (25OHD3) and by bone histomorphometry. This coexisting condition was caused by the long-term increase in conversion of 25OHD3 to 1,25(OH)2D3 from hyperparathyroidism in a patient with low stores of vitamin D (which were ascribed to aging, liver dysfunction in hyperthyroidism, a vegetarian diet, deprivation of sunlight, and avoidance of dairy products).

CONCLUSION

The complex concurrence of hyperthyroidism, PHP, and vitamin D-deficient osteomalacia is rare but possible.

Nutrition-related diseases and dietary change among Third World immigrants in northern Europe

Immigrants from the third world are more prone to acquire nutritional deficiency diseases, such as rickets, osteomalacia and iron deficiency anemia than the rest of the population in the recipient countries. Lately, evidence is also emerging that some immigrant groups are particularly susceptible to diseases related to overnutrition, such as coronary heart disease and non-insulin dependent diabetes. The purpose of this review article is to give a holistic view of the nutrition related diseases and disorders among immigrants. It deals with the prevalence of these diseases among immigrants in Northern European countries, and looks into some of the hypotheses, which have been put forward to explain why immigrant groups are more prone to acquire these diseases than the rest of the population. The focus of this part of the paper is the process of dietary change after migration. The practical implications of the findings from the literature review are then discussed.

The vitamin D status of East Indian Punjabi immigrants to Canada

1. Serum 25-hydroxyvitamin D (25-OHD), calcium and alkaline phosphatase (EC 3.1.3.1) levels and vitamin D intakes (from 3 d weighed dietary records) were determined in a cohort of fifty-nine male East Indian Punjabi immigrants (37.7 (SD 10.5) years) and fifty-four females (33.3 (SD 7.4) years). 2. Females had somewhat lower mean serum 25-OHD levels (12.3 (SD 5.0) v. 14.2 (SD 5.1) ng/ml, P less than 0.05) and serum Ca levels (88 (SD 8) v. 91 (SD 6) mg/l) than males (P less than 0.05) whereas serum alkaline phosphatase values (males 167 (SD 63), females 169 (SD 43) IU/l) and dietary vitamin D intakes (males 3.5 (SD 1.8), females 3.3 (SD 2.0) micrograms/d) were similar. 3. 22% of the females and 12% of the males had serum 25-OHD levels below 9.0 ng/ml but none had serum 25-OHD levels within the range associated with clinically overt disease. 4. In the males, serum 25-OHD levels were negatively correlated with dietary fibre intakes (g/d; r -0.29; P less than 0.05). 5. Multiple-regression analysis indicated that log serum 25-OHD levels were not related to dietary vitamin D intakes. Instead they were associated with sex and dietary fibre intakes (g/MJ) (F 3.71; P = 0.03). These two variables explained 8% of the variance.

Reduced plasma half-life of radio-labelled 25-hydroxyvitamin D3 in subjects receiving a high-fibre diet

1. The plasma disappearance of 3H-labelled 25-hydroxyvitamin D3 (25(OH)D3) was studied in healthy volunteers on normal and high-fibre diets, using 3H-labelled tracer doses given intravenously. 2. The mean (+/- SEM) plasma half-life in the high-fibre-diet group was 19.2 +/- 1.7 d, which was significantly shorter than in the group on normal diets (27.5 +/- 2.1 d, P less than 0.01). 3. This finding suggests that a high-fibre diet leads to enhanced elimination of 25(OH)D3 by an action within the intestinal lumen. This may involve interference with an enterohepatic circulation of the metabolite, perhaps by binding of 25(OH)D3 to dietary fibre. 4. The reduced plasma half-life of 3H-labelled 25(OH)D3 associated with a high-fibre diet may explain the development of vitamin D deficiency in Asian immigrants with normal exposure to u.v. light.

Failure to heal D-deficiency rickets and suppress secondary hyperparathyroidism with conventional doses of 1,25-dihydroxy vitamin D3

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Growth and bone mineralisation as affected by dietary calcium, phytic acid and vitamin D

1. Rats were fed various diets ranging from the normal chow, pure flour containing large amounts of phytic acid, Ca-enriched flour and mixtures of flour and normal food with various levels of calcium. 2. It was found that the animals eating the pure flour grew less and were smaller. 3. They suffered from hypocalcemia and had low plasma alkaline phosphatase and 25-HCC-vitamin D3 levels. 4. These animals had rib-cage deformities. 5. Additional calcium in the flour improved the animals' growth and calcification. 6. The mixed food did not greatly affect the animals and additional calcium did not improve growth or bone mineralisation. 7. The Bedouin eat large amounts of unleavened bread containing large amounts of phytates. 8. It is concluded that uptake of large amounts of phytates by the Bedouin eating unleavened bread is due to the flour and that the clinical manifestations are a direct result of the flour and not the lack of vitamin D due to covering the skin from sunlight.

Phytic acid interactions in food systems

Phytic acid is present in many plant systems, constituting about 1 to 5% by weight of many cereals and legumes. Concern about its presence in food arises from evidence that it decreases the bioavailability of many essential minerals by interacting with multivalent cations and/or proteins to form complexes that may be insoluble or otherwise unavailable under physiologic conditions. The precise structure of phytic acid and its salts is still a matter of controversy and lack of a good method of analysis is also a problem. It forms fairly stable chelates with almost all multivalent cations which are insoluble about pH 6 to 7, although pH, type, and concentration of cation have a tremendous influence on their solubility characteristics. In addition, at low pH and low cation concentration, phytate-protein complexes are formed due to direct electrostatic interaction, while at pH > 6 to 7, a ternary phytic acid-mineral-protein complex is formed which dissociates at high Na+ concentrations. These complexes appear to be responsible for the decreased bioavailability of the complexed minerals and are also more resistant to proteolytic digestion at low pH. Development of methods for producing low-phytate food products must take into account the nature and extent of the interactions between phytic acid and other food components. Simple mechanical treatment, such as milling, is useful for those seeds in which phytic acid tends to be localized in specific regions. Enzyme treatment, either directly with phytase or indirectly through the action of microorganisms, such as yeast during breadmaking, is quite effective, provided pH and other environmental conditions are favorable. It is also possible to produce low-phytate products by taking advantage of some specific interactions. For example, adjustment of pH and/or ionic strength so as to dissociate phytate-protein complexes and then using centrifugation or ultrafiltration (UF) has been shown to be useful. Phytic acid can also influence certain functional properties such as pH-solubility profiles of the proteins and the cookability of the seeds.

The nutritional and physiological impact of cereal products in human nutrition

There is a need for reeducation of the population, especially in developed countries, as to the value of cereals in the diet. Cereals provide calories and important nutrients to the diet. Refined cereal products and unrefined cereals have certain advantages and disadvantages. With refinement, some nutrients and fiber are removed, but the body is better able to make use of certain nutrients. Essential nutrients are being replaced through fortification to compensate for losses in processing. The high fiber content of unrefined cereal products is believed to aid in the prevention of certain diseases. Special dietary bakery products have been introduced for the treatment of conditions generally exacerbated by standard food items. The increased consumption of cereal products appears warranted as a means of decreasing the saturated fat and cholesterol consumption. Cereals and cereal products have been mentioned in connection with allergies, celiac disease, schizophrenia, obesity, dental caries, cancer, atherosclerosis, goiter, and diverticulosis. This review discusses the possible role of cereals in the prevention or cause of these health problems.

A possible relationship between high-extraction cereal and rickets and osteomalacia

The evidence of the present study suggests a strong and possibly causal relationship between high-extraction cereal and rickets and osteomalacia. It seems likely that this occurs when vitamin-D status is border-line. The rachitogenic component of high-extraction cereal remains to be identified; dietary phytate now seems unlikely and phytate-derived polyphosphate esters or dietary phosphorus may be incriminated. The present study strongly indicates that Mellanby's original suggestion of an "anti-calcifying substance" in high-extraction cereal remains valid.

Vitamin D status in different subgroups of British Asians

To assess the effect of religious dietary practices and social customs on the vitamin D status of Asian immigrants, we kept records of the dietary intake and time spent out of doors of 81 Ugandan Asian men, women, and girls (9-19 years old). Sera were analysed for 25-hydroxycholecalciferol (25-OHD3), and 28% of the subjects were found to have levels below the lower limit of normal. The (vegetarian) Hindus had the lowest dietary intakes, least time out of doors, and lowest serum 25-OHD3. The Goan (Roman Catholic) Asians, despite more pigmentation, had 25-OHD3 levels similar to those found among indigenous British people and had the most satisfactory vitamin D intakes. Among Asians, whose exposure to sunlight may be limited, dietary vitamin D becomes the major determinant of serum 25-OHD3.

Florid and subclinical rickets among immigrant children in Glasgow

200 Asian 300 African, Chinese, or Scottish children were examined for clinical, biochemical, and radiological evidence of vitamin-D deficiency. Among the Asians there were 10 with florid rickets and 15 with subclinical rickets. Among the African, Chinese, and Scottish children there were no cases of florid rickets and only 7 cases of subclinical rickets (3 African, 3 Chinese, and 1 Scottish). Loss of metaphyseal definition is considered to be the radiological pattern of minimal active rickets and metaphyseal bands to represent the healing stage. Serum 25-hydroxycholecalciferol concentrations were low in clinical and subclinical minimal active rickets although there was some overlap with the wide range found in the "normal" group. Elevated serum-alkaline-phosphatase levels alone should not be regarded as indicating vitamin-D deficiency. The continuing prevalence of rickets in Asian children and in particular among schoolchildren warrants immediate action, which is long overdue.

Plasma calcium levels in pregnant Asian women

Plasma calcium, phosphorus, alkaline phosphatase, total protein, and albumin were measured during pregnancy in a group of Asian women living in the south of England and in a control group. The Asian women had slightly lower mean plasma calcium concentrations than the control group. Exposure of Asian women to sunshine appeared to be low, and it was inferred that they probably had little endogenous synthesis of cholecalciferol as a result. Both Asian and control subjects ingested similarly low amounts of vitamin D. The Asian women consumed greater amounts of phytate and vegetable fibres than the controls, and it is suggested that these substances may reduce absorption of insoluble lipids (including cholecalciferol) and calcium in a setting where the dietary intake and endogenous synthesis of vitamin D are already borderline for the subject's requirements.

Hereditary pseudo vitamin D deficiency rickets in a Pakistani infant

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Nutritional rickets at puberty

Four adolescent Asians with vitamin D deficiency rickets were seen in Derby in the 5 years 1967 to 1971. They had an extremely low intake of vitamin D, and this, combined with the extra metabolic demands of puberty, was judged to be the main cause of the rickets. However, since investigation of their sibs revealed 4 further cases of rickets, it is possible that some of these children had an inherited disability in the metabolism of vitamin D. 2 cases of iron deficiency anaemia were found among their sibs. We suspect that nutritional deficiencies may be widespread in the Asian community in Britain and that prevention depends on dietary education.