First voyage of James Cook Cook had lost not a single man to scurvy, a remarkable and practically unheard-of achievement in 18th-century long-distance seafaring. Adhering to Royal Navy policy introduced in 1747, Cook persuaded his men to eat foods such as citrus fruits and sauerkraut. At that time it was known that poor diet caused scurvy but not specifically that a vitamin C deficiency was the culprit. Sailors of the day were notoriously against innovation, and at first the men would not eat the sauerkraut. Cook used a "method I never once knew to fail with seamen." He ordered it served to himself and the
Vitamin D and neurology vitamin D blood concentration standard for diagnosing hypovitaminosis D does not exist. In the past, hypovitaminosis D has been defined by blood concentrations lower than 20 ng/ mL. However, in more recent literature many researchers have considered 30 ng/ mL to be an insufficient concentration of vitamin D. Subnormal levels of vitamin D are usually caused by poor nutrition or a lack of sun exposure. Risk factors for hypovitaminosis D include premature birth, darker skin pigmentation, obesity, malabsorption, and older age. The brain requires the use of many neurosteroids to develop and function properly. These molecules are often identified as