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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
Women are two-thirds more likely than men to develop irritable bowel syndrome. This may be attributable to hormonal changes related to their menstrual cycles.
Calcitonin is a naturally occurring hormone. In women who are at least 5 years beyond menopause, it slows bone loss and increases spinal bone density.
The people with the highest levels of LDL are Mexican American males and non-Hispanic black females.