Author: Smith

Once initiated, the HPA axis begins in the brain structure known as the hypothalamus—the H in HPA. One of the most important functions of the hypothalamus (aside from its role as a metabolic master controller) is to link the brain to the body’s hormone system via the pituitary gland. The hypothalamus sends out some corticotropin-releasing hormone (CRH) to the pituitary gland—the meat in the HPA sandwich. After receiving word of turmoil from the hypothalamus, the pituitary gland then secretes something c a l l e d adrenocorticotropic hormone (ACTH) into circulation. (Recall that hormones are long-range messengers, which differ from…

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In adults, growth hormone, or GH, is known primarily for its role as a repair hormone. Athletes have been known to use GH for its performance-enhancing qualities, namely its ability to accelerate repair of connective tissue. But GH, which is secreted by the brain’s pituitary gland, is also a powerful cognitive modulator, shown to improve many aspects of brain function, including processing speed and mood. In older adults, GH replacement therapy has been shown to boost cognitive function in patients with mild cognitive impairment (pre-dementia that often leads to Alzheimer’s disease) and in healthy controls after just five months. 17…

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Sleep can also negatively affect another hormone involved in hunger called leptin. Leptin is the “satiety” hormone that helps regulate energy balance by inhibiting hunger, and it plummets with sleep deprivation. Leptin’s job is to control energy expenditure through its action on the hypothalamus, the brain’s master metabolic regulator. Because leptin is secreted by fat cells, the more fat cells one has, the more circulating leptin. The brain interprets higher levels of leptin as permission to open up the throttle a bit on the rate at which our bodies burn calories—after all, food is seemingly plentiful! But as with insulin,…

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Crew Anatomy textbooks are not updated too often these days. After the advent of the microscope, physiologists were quick to slice, dice, stain, map, and draw every square millimeter of the human body—and within a few short decades, there was seemingly nothing left to explore. So it was a major geek-out moment for biology lovers when Jeffrey Iliff and his team at the University of Rochester discovered what could rightly be called an uncharted organ —th e glymphatic system. This system forcefully pushes cerebrospinal fluid through the brain while we sleep, providing a free power-wash for our brains every single…

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Growing up in New York City, I would always feel my spirits drop come the fall. The impending winter months of long, dark days with little sun exposure gave rise to a kind of depression known as seasonal affective disorder, or SAD. Also known as winter depression, SAD affects an estimated ten million people in the United States—and while the majority of those affected are women, everybody is at risk. When I was seventeen, I learned that the skin made vitamin D from exposure to the sun, and I realized that my lack of sun exposure during those dark months…

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Have you seen a baby lately? I’m talking about a newborn, fresh out of the womb. They’re fat. And cute. But mostly fat. Packed with stored energy prior to birth in the third trimester, the fatness of human babies is unprecedented in the mammal world. While the newborns of most mammal species average 2 to 3 percent of birth weight as body fat, humans are born with a body fat percentage of nearly 15, surpassing the fatness of even newborn seals. Why is this so? Because humans are born half-baked. When a healthy human baby emerges from the womb, she…

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Bacteria In industrialized countries, and based on reports from those that have carried out comprehensive assessments of the number of illnesses, hospitalizations and deaths from contaminated foods, the most common causes of foodborne illness are norovirus, Salmonella enterica, Campylobacter spp., Clostridium perfringens and Staphylococcus aureus, (Scallan et al. 2011a, 2013; Adak et al. 2002; Hall and Kirk 2005). Due to its high case fatality rate, L. monocytogenes has also become a much noted cause for concern. Scallan et al. (2011a) reported that norovirus was responsible for most (58%) foodborne illness in the US, while non-typhoidal Salmonella was the leading cause of hospitalizations and…

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Our brains are massive oxygen consumers. Twenty-five percent of every breath you take is going directly to support the ravenous metabolic needs of your brain, and ensuring that your blood lipids are healthy is one way of keeping your cognitive power supply free of interruption. Thankfully, there are some other ways of increasing healthy blood flow to the brain: Eat dark chocolate. Compounds in dark chocolate (called polyphenols) have been shown to boost brain perfusion, or blood flow to the brain. As we learned with Genius Food #4, stick to 80% or higher for the cocoa content (ideally 85% or…

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Once you are fat adapted, periodic high-carb meals can be a potent way of promoting healthy leptin dynamics. This is because carbohydrate consumption and the insulin secreted as a result are powerful leptin boosters. 14 The corresponding leptin surge messages the hypothalamus to ramp up the body’s metabolic engines. This system becomes dysregulated if there is chronic high-carbohydrate consumption, which can promote leptin resistance. But when combined with exercise, a weekly higher-carb “refeed” can increase energy expenditure, recalibrate mood, and accelerate fat loss, especially for those who’ve seen their weight loss stall. A refeed of 100 to 150 grams of…

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Ready for a paradigm shift? Some very interesting studies have emerged recently highlighting the value that probiotics–foods or supplements rich in live bacteria–may hold for those of us suffering from depression, anxiety, and even dementia. In a small study from Holland’s Leiden Institute for Brain and Cognition, women who took a probiotic supplement designed to enhance gut bacterial diversity experienced less reactivity to sad thoughts than those who took a placebo. Resilience to sad thoughts is a sign of strong mental health. For example, in depressed people, a sad stimulus can turn an otherwise spotless sky into an overcast day,…

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