Subclinical health effects in a population exposed to excess vitamin D in milk

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

Iatrogenic vitamin D toxicity in an infant--a case report and review of literature

Public concern over vitamin D deficiency has led to widespread use of over the counter (OTC) vitamin D (-D3 or -D2) supplements, containing up to 10,000 IU/unit dose (400 IU=10μg). Overzealous use of such supplements can cause hypercalcemia due to vitamin D toxicity. Infants are particularly vulnerable to toxicity associated with vitamin D overdose. OTC supplements are not subject to stringent quality control regulations from FDA and high degree of variability in vitamin D content in OTC pills has been demonstrated. Other etiologies of vitamin D induced hypercalcemia include hyperparathyroidism, granulomatous malignancies like sarcoidosis and mutations in the CYP24A1 gene. The differential diagnosis of hypercalcemia should include iatrogenic and genetic etiologies. C24-hydroxylation and C3-epimerization are two important biochemical pathways via which 25-hydroxyvitamin D3 (25(OH)D3) is converted to its metabolites, 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) or its C3 epimer, 3-epi-25-OH-D3 respectively. Mutations in the CYP24A1 gene cause reduced serum 24,25(OH)2D3 to 25(OH)D3 ratio (<0.02), elevated serum 1,25-dihydroxyvitamin D (1,25(OH)2D3), hypercalcemia, hypercalciuria and nephrolithiasis. Studies in infants have shown that 3-epi-25(OH)D3 can contribute 9-61.1% of the total 25(OH)D3. Therefore, measurements of parathyroid hormone (PTH) and vitamin D metabolites 25(OH)D3, 1,25(OH)2D3, 3-epi-25(OH)D3 and 24,25(OH)2D3 are useful to investigate whether the underlying cause of vitamin D toxicity is iatrogenic versus genetic. Here we report a case of vitamin D3 associated toxicity in a 4-month-old female who was exclusively breast-fed and received an oral liquid vitamin D3 supplement at a dose significantly higher than recommended on the label. The vitamin D3 content of the supplement was threefold higher (6000 IU of D/drop) than listed on the label (2000 IU). Due to overdosing and higher vitamin D3 content, the infant received ∼50,000 IU/day for two months resulting in severe hypercalcemia, hypercalciuria and nephrocalcinosis. We also review the relevant literature on vitamin D3 toxicity in this report.

New perspectives on vitamin D food fortification based on a modeling of 25(OH)D concentrations

BACKGROUND

In Germany, vitamin D intake from food and synthesis in the skin is low, which leads to low 25(OH)D serum concentrations. In contrast to many other countries, general vitamin D food fortification is still prohibited in Germany, although the European Commission published a regulatory framework to harmonize addition of vitamins to foods. Thus the purpose of our study was to develop a vitamin D fortification model, taking into account all vitamin D sources with the goal to fulfill requirements of intake recommendations or preferable 25(OH)D serum concentrations. Finally, the aim was to assess the suitability of different carriers and associated risks.

METHODS

We developed a mathematical bottom-up model of 25(OH)D serum concentrations based on data about vitamin D sources of the German population such as sunlight, food and supplements for all federal states taking seasonal and geographical variations into account. We used this model to calculate the optimal fortification levels of different vitamin D carriers in two approaches. First we calculated required fortification levels based on fixed intake recommendations from e.g. the IOM or the DGE and second based on achieving certain 25(OH)D serum concentrations.

RESULTS

To lift 25(OH)D serum concentration in Germany to 75 nmol/L, e.g. 100 g bread has to be fortified with 11.3 μg during winter, resulting in a daily vitamin D intake of 23.7 μg. Bread seems to be a suitable carrier for base supply. However, overdose risk with a single fortified product is higher than the risk with several fortified carriers.

CONCLUSIONS

With the model in hand, it is possible to conceive vitamin D fortification strategies for different foodstuffs and model its impact on 25(OH)D serum concentrations.

Hypercalcemia due to hypervitaminosis D: report of seven patients

We retrospectively studied seven children (six girls, one boy) aged from 7.5 to 25 months who presented to our institution after taking large doses of vitamin D (900 000-4 000 000 U) prescribed by medical practitioners for wrong indications like failure to thrive, etc. The clinical manifestations were constipation, decreased appetite, lethargy, polyuria, dehydration and failure to thrive. All patients had hypercalcemia (serum calcium ranging from 12 to 16.8 mg/dl), high 25[OH]D levels (ranging from 96 to >150 ng/ml), suppressed intact parathyroid hormone (ranging from <3 to 8.1 pg/ml). Hypercalciuria (urinary calcium/creatinine ranging from 1 to 2.45) was found in all patients, while nephrocalcinosis was present in five patients. All were treated with intravenous fluids, oral prednisolone, restriction of calcium in diet, while four patients received pamidronate infusion for reducing hypercalcemia.

Vitamin D requirement and setting recommendation levels: long-term perspectives

Target intakes of vitamin D to prevent rickets and osteomalacia are difficult to estimate because of the dual sources of vitamin D with dermal production and absorption from the intestine. However, vitamin D deficiency is associated with other diseases, e.g., myopathy, falls, fractures, autoimmune disorders, cardiovascular diseases, and malignancies, which underlines the necessity of redefining recommendations. A plasma level of 25-hydroxyvitamin D (25OHD) <50 nmol/L increases the risk of secondary hyperparathyroidism, whereas levels between 75 and 100 nmol/L appear optimal for maintaining general health. In adults, a minimum dietary intake of 17.5-25 microg/day is necessary to achieve these levels. Perspectives of future research are outlined here.

Development of a model for optimal food fortification: vitamin D among adults in Finland

BACKGROUND

Average vitamin D intake is low in Finland. Even though almost all retail milk and margarine are fortified with vitamin D, the vitamin D intake is inadequate for a significant proportion of the population. Consequently, expanded food fortification with vitamin D would be motivated. However, there is a risk of unacceptably high intakes due to the rather narrow range of the adequate and safe intake. Therefore, a safe and efficient food fortification practice should be found for vitamin D.

AIM OF THE STUDY

To develop a model for optimal food fortification and apply it to vitamin D.

METHOD

The FINDIET 2002 Study (48-h recall and data on supplement use (n = 2007), and 3 + 3 days' food records, n = 247) was used as the test data. The proportion of the population whose vitamin D intake is between the recommended intake (RI) and the upper tolerable intake level (UL) was plotted against the fortification level per energy for selected foods. The fortification level that maximized the proportion of the population falling between RI and UL was considered the optimal fortification level.

RESULTS

If only milk, butter milk, yoghurt and margarine were fortified, it would be impossible to find a fortification level by which the intake of the whole population would lie within the RI-UL range. However, if all potentially fortifiable foods were fortified with vitamin D at level 1.2-1.5 microg/100 kcal, the intake of the whole adult population would be between the currently recommended intake of 7.5 microg/d and the current tolerable upper intake level of 50 microg/day (model 1). If the RI was set to 40 microg/day and UL to 250 microg/day, the optimal fortification level would be 9.2 microg/100 kcal in the scenario where all potentially fortifiable foods were fortified (model 2). Also in this model the whole population would fall between the RI-UL range.

CONCLUSIONS

Our model of adding a specific level of vitamin D/100 kcal to all potentially fortifiable foods (1.2-1.5 microg/100 kcal in model 1 and 9.2 microg/100 kcal in model 2) seems to be an efficient and safe food fortification practise.

Fortification of industrialized foods with vitamins

Vitamins are essential to life. Inadequate eating habits, high caloric intake and metabolic defects lead to micronutrient deficiencies, affecting more than two billion people worldwide. The increasing intake of industrialized foods, combined with low vitamin stability has led to the common practice of adding these nutrients to processed foods. This review discusses the terminology, availability, intake and risk of hypervitaminosis, due to the intake and nutritional importance of foods fortified with vitamins. The addition of nutrients should occur in foods that are effectively consumed by the target population and must meet the real needs of a significant segment of the population. In Brazil, a total of 166 products available in supermarkets are vitamin-enriched. A 10-year study involving children and adolescents in Germany showed that 90% of those surveyed used at least one fortified food. During this 10-year period, 472 fortified products were consumed. The enrichment of foods should be based on the needs of each country and, if possible, regional needs. For instance, in order to increase its intake, Vitamin D is added to foods in Denmark during the winter, mainly for the elderly. However, in Brazil, there is no evidence of the need to fortify food with this vitamin. A survey showed that of the 76 enriched dairy products, 37 contained vitamin D. Food-fortification is a very important strategy to solve nutritional deficiency problems, but it can also cause many health problems.

Vitamin D and the elderly

This review summarizes current knowledge on vitamin D status in the elderly with special attention to definition and prevalence of vitamin D insufficiency and deficiency, relationships between vitamin D status and various diseases common in the elderly, and the effects of intervention with vitamin D or vitamin D and calcium. Individual vitamin D status is usually estimated by measuring plasma 25-hydroxyvitamin D (25OHD) levels. However, reference values from normal populations are not applicable for the definition of vitamin D insufficiency or deficiency. Instead vitamin D insufficiency is defined as the lowest threshold value for plasma 25OHD (around 50 nmol/l) that prevents secondary hyperparathyroidism, increased bone turnover, bone mineral loss, or seasonal variations in plasma PTH. Vitamin D deficiency is defined as values below 25 nmol/l. Using these definitions vitamin D deficiency is common among community-dwelling elderly in the developed countries at higher latitudes and very common among institutionalized elderly, geriatric patients and patients with hip fractures. Vitamin D deficiency is an established risk factor for osteoporosis, falls and fractures. Clinical trials have demonstrated that 800 IU (20 microg) per day of vitamin D in combination with 1200 mg calcium effectively reduces the risk of falls and fractures in institutionalized patients. Furthermore, 400 IU (10 microg) per day in combination with 1000 mg calcium or 100 000 IU orally every fourth month without calcium reduces fracture risk in individuals over 65 years of age living at home. Yearly injections of vitamin D seem to have no effect on fracture risk probably because of reduced bioavailability. Simulation studies suggest that fortification of food cannot provide sufficient vitamin D to the elderly without exceeding present conventional safety levels for children. A combination of fortification and individual supplementation is proposed. It is argued that all official programmes should be evaluated scientifically. Epidemiological studies suggest that vitamin D insufficiency is related to a number of other disorders frequently observed among the elderly, such as breast, prostate and colon cancers, type 2 diabetes, and cardiovascular disorders including hypertension. However, apart from hypertension, causality has not been established through randomized intervention studies. It seems that 800 IU (20 microg) vitamin D per day in combination with calcium reduces systolic blood pressure in elderly women.

Dental changes in hypervitaminosis D

Vitamin D is required for the normal development of teeth and bones. When there is excess vitamin D, systemic and dental changes may occur. This is a case report of a girl who experienced hypercalcemia secondary to excess vitamin D derived from the consumption of milk that was incorrectly fortified. The changes in the permanent dentition to date are enamel hypoplasia and focal pulp calcification. These changes correspond to the timing of the toxemia caused by hypervitaminosis D.