Nutritional endocrine disorders

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Review Article

Nutritional endocrine disorders K. V. S. Hari Kumar, M. M. Baruah Department of Endocrinology, Command Hospital, Central Command, Lucknow, Uttar Pradesh, India

A B S T R A C T Diseases of the endocrine glands highlight the importance of hormonal and nutritional factors in the regulation of metabolism in human beings. The nutritional alterations affect each and every aspect of the functioning of the endocrine glands leading to serious disorders. The last century was marked by the classical deficiency disorders, such as goiter, cretinism, hypothyroidism, and rickets. Industrialization coupled with increased availability of junk food leads to the epidemic of different nutritional endocrine disorders, such as obesity, metabolic syndrome, and diabetes. Endocrine disruptors are the new kids on the block with a variety of implications ranging from obesity to pubertal disorders. We give a concise outlook on various nutritional endocrine disorders in this review. Key words: Calcium, endocrinology, iodine, nutrition, vitamin D

Introduction Nutrition and endocrinology are linked from time immemorial with the premise that adequate nutrition is required for statural growth. The spectrum is expanded later with recognition of thyroid disorders resulting from iodine deficiency in certain geographic areas.[1] Further the link between rickets and calcium and vitamin D deficiency was established leading to fortification of many food substances with vitamin D.[2] The association between childhood obesity leading to the metabolic consequences in adult life is a matter of great concern during the last couple of decades.[3] The last decade is buzzing with the effects of endocrine disruptors on various hormonal axes affecting the puberty and other functions in the latest generation.[4] It is evident from these reports that the endocrine gland function is affected by nutritional alterations. Nutritional endocrine disorders are characterized by alteration in the function or structure of the endocrine Access this article online Quick Response Code:

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glands with resulting clinical consequences due to the deficiency or excess of a dietary compound. The nutrients in the food are subdivided into major and minor nutrients. Carbohydrates, proteins, and fats constitute the major nutrients, whereas vitamins and minerals form the minor nutrients. Most of the nutritional endocrine disorders result from nutritional deficiency barring few disorders, such as obesity and diabetes, due to nutrient excess. From an era of nutrient deficiency disorders, such as short stature and rickets, we have evolved into nutrient excess conditions, such as obesity and metabolic syndrome. The spectrum of nutritional endocrine disorders is summarized in Table 1. In this article, we shall give a concise overview of the important nutrient endocrine disorders and relevant dietary recommendations. Nutritional thyroid disorders

Micronutrients, mostly iodine and selenium, are required for thyroid hormone synthesis and function. Iodine is an essential component of thyroid hormones and its deficiency is considered as the most common cause of preventable brain damage in the world.[1] Iodine deficiency disorders include goiter, hypothyroidism, and mental retardation, and are shown in Table 2. Iodine supplementation, in the form of iodized salt resulted in decrease of these disorders in the last few decades. Increased carbohydrate content in the diet results in a higher T3 production, leading to increased iodine requirement. The higher iodine requirement exceeds the availability of iodine

Corresponding Author: Dr. K. V. S. Hari Kumar, Department of Endocrinology, Command Hospital, Central Command, Lucknow - 226 002, Uttar Pradesh, India. E-mail: [email protected]

Journal of Medical Nutrition and Nutraceuticals, Vol 1 / Issue1 / Jan-Jun 2012

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Hari Kumar and Baruah: Nutritional endocrine disorders

from environmental sources in many regions of the world, resulting in the development of iodine deficiency disorders. Iodine excess is implicated in predisposition to autoimmune thyroid disease and rarely hyperthyroidism, which also known as Jod–Basedow phenomenon.[5]

Table 1: Nutritional endocrine disorders

Three different selenium-dependent iodothyronine deiodinases (types I, II, and III) are essential in physiology of thyroid hormones, making selenium an essential micronutrient for optimal thyroid function. Furthermore, selenium is found as selenocysteine in the catalytic center of enzymes protecting the thyroid from free radical damage. Substances introduced with food, such as thiocyanate and isoflavones interfere with micronutrients and influence thyroid function. Other micronutrients that have an essential role in thyroid function are iron, perchlorate, zinc, and vitamin A.[6] A deficiency of these micronutrients alone or together affects iodine nutrition and thyroid function, highlighting the importance of a balanced nutritious diet.

Bone

Nutrient alteration

Disorder

Thyroid

Iodine deficiency Selenium deficiency Iodine excess Iodine excess Calcium/Vit D deficiency Calcium/Vit D deficiency Fluoride excess Cow milk consumption Malnutrition

Goiter/hypothyroidism Goiter/hypothyroidism Hyperthyroidism Autoimmune thyroid disease Rickets/osteomalacia Osteoporosis Fluorosis Type-1 diabetes Malnutrition-related diabetes mellitus Fibrocalcific pancreatic disease Obesity/diabetes Diabetes Pubertal disorders Hypogonadism, bone loss, amenorrhea Short stature

Metabolic

Cassava consumption

Gonads Growth

Caloric excess Chromium deficiency Endocrine disruptors Anorexia nervosa Malnutrition including macro- and micronutrient deficiency

Table 2: Iodine deficiency disorders

Nutritional bone disorders

Nutrition plays a major role in the prevention and treatment of bone disorders, such as rickets, osteomalacia, and osteoporosis.[2] The macronutrients of major importance are dietary protein intake and the micronutrients of greatest importance are calcium and vitamin D. Vitamin D deficiency in childhood predisposes to osteoporosis and nonskeletal disorders, such as diabetes mellitus, cancer, and multiple sclerosis.[7] The other micronutrient needs for optimum bone health are explained in Table 3. Rickets/osteomalacia Adequate calcium intake is the most critical nutritional factor to achieve optimal peak bone mass. Vitamin D is essential for intestinal calcium absorption. Low calcium in the setting of vitamin D deficiency leads to stimulation of parathyroid gland, which leads to release of calcium and phosphorus from the bone.[2] The cumulative effects are decreased bone mineralization and disorganized growth leading to characteristic deformities. Milk and dairy products are an optimal source of calcium and sunlight for vitamin D. Nutritional rickets is a disease of growing bones caused by calcium and vitamin D deficiency or both in combination. Rickets is characterized by delayed fontanelle closure, enlarged wrists, rickety rosary, craniotabes, enamel hypoplasia, and skeletal deformities. A daily intake of 400–800 IU of vitamin D along with 1000 mg of calcium is recommended to prevent the nutritional bone disorders. Rich sources of vitamin D include fatty fish, fish-liver oils (cod liver oil), and liver and dietary sources of calcium are dairy products (milk, yogurt, cheese), dark green vegetables, and nuts. 6

Endocrine system

Age group

Disorders

All ages Fetus Neonate Children Adults

Goiter, hypothyroidism, radiation susceptibility Abortion, still birth, congenital anomalies Infant mortality, endemic cretinism Subnormal mentation, delayed development Impaired mental function, poor performance

Table 3: Micronutrients affecting bone metabolism Micronutrient

Functional role in bone physiology

Phosphorus

• Phosphorus deficiency limit osteoblast function and enhance osteoclastic bone resorption • Low serum phosphate will limit bone formation and mineralization • High phosphorus and low calcium lead to secondary hyperparathyroidism and bone loss. • Higher salt intake leads to higher levels of parathyroid hormone and greater rates of bone resorption • Increased sodium intake leads to increased renal calcium excretion • Low potassium diets increase urinary calcium losses and high potassium diets reduce it • Increased potassium intake ameliorates the higher bone resorption seen with high-salt diets • Facilitates carboxylation of proteins, such as osteocalcin • Reduces urinary calcium excretion • Vitamin K antagonists lead to undercarboxylation of anabolic proteins, such as osteocalcin • Vitamin C is essential for collagen formation and synthesis of hydroxyproline and hydroxylysine • Low intakes of vitamin are associated with a faster rate of decline in bone mineral density • Vitamin A is required for bone remodeling and excess levels are detrimental to bone health • Higher magnesium intakes are associated with higher bone mineral density • Adequate intake of boron, copper, zinc, and silicon is essential for good bone nutrition

Sodium

Potassium

Vitamin K

Vitamin C

Vitamin A Magnesium Others

Journal of Medical Nutrition and Nutraceuticals, Vol 1 / Issue1 / Jan-Jun 2012


Hari Kumar and Baruah: Nutritional endocrine disorders

Osteoporosis Osteoporosis is a disease characterized by low bone mass, microarchitectural deterioration leading to increased fracture risk of the bones. In addition to calcium and vitamin D, other micronutrients and their relevant functions in bone health are shown in Table 3. Excess dietary protein is detrimental to bone health due to hypercalciuria and acidosis.[8] Hypercalciuria is due to increased glomerular filtration rate and decreased tubular calcium reabsorption, resulting in negative calcium balance. Fluorosis Fluorosis is a skeletal disease caused by the consumption of excess fluoride. The common cause in India is the consumption of ground water from bore wells, which have an unacceptably high fluoride levels.[9] The disease is endemic in certain southern states, such as Andhra Pradesh. Excess fluorine forms an insoluble salt-like calcium fluoride leading to increased bone density but decreased bone strength. The disease is characterized by pain and stiffness of joints, arthritis, enamel abnormalities, skeletal deformities, and other systemic effects. The best way to prevent the problem is defluoridation of water prior to consumption. Nutritional metabolic disorders including diabetes

The world is grappling with increased prevalence of obesity, diabetes, and associated metabolic disorders in children and adults. The primary reason for this excess prevalence is due to increased calorie consumption on a background genetic predisposition. Although obesity is the leading nutritional endocrine disorder we shall restrict our discussion to other metabolic disorders, including diabetes: Type-1 diabetes The development of type-1 diabetes mellitus is thought to be related to environmental trigger factors acting upon a background of genetic predisposition. Apart from congenital rubella infection, other infections, toxins, and dietary factors are considered as causative factors. The nutritional factors proposed to increase the risk of type-1 diabetes mellitus are the early introduction of bovine milk, and cereals in less than 3 months age infants.[10] Fibrocalcific pancreatic disease (FCPD) Malnutrition-related diabetes mellitus is an entity described from Asia and Sub-Saharan Africa and was subdivided into protein-deficient diabetes mellitus and fibrocalculous pancreatic disease. The dietary factors claimed to have a pathophysiologic role in FCPD are cyanide toxicity from consumption of cassava, another starchy root Ensete

ventricosum in Africa, and cabbage intake.[11] The recent WHO classification of diabetes merged the two entities and retained the FCPD (also known as type-3C diabetes), which has the following characteristics: i. Prevalence in a defined geographic area ii. Consumption of low proteins