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The fat-fueled brain: unnatural or advantageous?

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HEAL YOUR BRAIN with bacon and full-fat cheeses!

Two caveats:

Data exploring the potential neuroprotective effects of ketosis are still scarce, and we don’t yet know the side effects of a long-term ketogenic diet.

The science of ketosis:

In essence, a ketogenic diet mimics starvation, allowing the body to go into a metabolic state called ketosis (key-tow-sis). Normally, human bodies are sugar-driven machines: ingested carbohydrates are broken down into glucose, which is mainly transported and used as energy or stored as glycogen in liver and muscle tissue. When deprived of dietary carbohydrates (usually below 50g/day), the liver becomes the sole provider of glucose to feed your hungry organs – especially the brain, a particularly greedy entity accounting for ~20% of total energy expenditure. The brain cannot DIRECTLY use fat for energy. Once liver glycogen is depleted, without a backup energy source, humanity would’ve long disappeared in the eons of evolution.

The backup is ketone bodies that the liver derives primarily from fatty acids in your diet or body fat. These ketones – ?-hydroxybutyrate (BHB), acetoacetate and acetone – are released into the bloodstream, taken up by the brain and other organs, shuttled into the “energy factory” mitochondria and used up as fuel. Excess BHB and acetoacetate are excreted from urine, while acetone, due to its volatile nature, is breathed out (hence the characteristically sweet “keto breath”). Meanwhile, blood glucose remains physiologically normal due to glucose derived from certain amino acids and the breakdown of fatty acids – voila, low blood sugar avoided!

Ketosis can protect against brain diseases?!

Despite their superficial differences, many neurological diseases share one major problem – deficient energy production. During metabolic stress, ketones serve as an alternative energy source to maintain normal brain cell metabolism. In fact, BHB (a major ketone) may be an even more efficient fuel than glucose, providing more energy per unit oxygen used. A ketogenic diet also increases the number of mitochondria, so called “energy factories” in brain cells. A recent study found enhanced expression of genes encoding for mitochondrial enzymes and energy metabolism in the hippocampus, a part of the brain important for learning and memory. Hippocampal cells often degenerate in age-related brain diseases, leading to cognitive dysfunction and memory loss. With increased energy reserve, neurons may be able to ward off disease stressors that would usually exhaust and kill the cell.

A ketogenic diet may also DIRECTLY inhibit a major source of neuronal stress, by -well- acting like a blueberry. Reactive oxygen species are unfortunate byproducts of cellular metabolism. Unlike the gas Oxygen, these “oxidants” have a single electron that makes them highly reactive, bombarding into proteins and membranes and wrecking their structure. Increased oxidants are a hallmark of aging, stroke and neurodegeneration.

Ketones directly inhibit the production of these violent molecules, and enhance their breakdown through increasing the activity of glutathione peroxidase, a part of our innate anti-oxidant system. The low intake of carbohydrates also directly reduces glucose oxidation (something called “glycolysis”). Using a glucose-like non-metabolized analogue, one study found that neurons activate stress proteins to lower oxidant levels and stabilize mitochondria.

Due to its high fat nature, keto increases poly-unsaturated fatty acids (PUFAs, such as DHA and EPA, both sold over-the-counter as “brain healthy” supplements), which in turn reduces oxidant production and inflammation. Inflammatory stress is another “root of all evil”, which PUFAs target by inhibiting the expression of genes encoding for pro-inflammatory factors.

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