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Douglas Bader:Was one of the greatest fighter pilots in history.And he did it without legs. He’d lost them during a training accident. Consequently, he says he was able to hold more G’s without fainting than most pilots during dogfights (people faint when they are unable to get oxygen to their brain) This was a key advantage during World War 2 when air combat was much more intimate and planes were cutting steep, fast angles to avoid being shot out of the sky.Presumably, his amputations made it easier for him to store blood up near his head as there were fewer places to have to send all the blood.His fighter plane was specially modified for him to use prosthetics during his air combat missions. Regardless of whether it was true or not, he is a very impressive man.

I’d say that just about every claim about nutrition is a myth or, at best, a vast oversimplification of a complex question.The truth is that studying the effects of diet on health is preposterously hard for a great many reasons:People lie about what they eat“Health” is ill-definedThe same food can have different effects on different peopleWhen you ask people to modify their diets in one way, they will modify them in other ways as wellMany of the effects of a particular food (say, Porterhouse steak) on a particular aspect of health (say, blood pressure) are nonmonotonic.Many measures of health are nonmonotonic (e.g. very low blood pressure is bad, so is very high blood pressure).Many things that are bad for one aspect of health are good for other aspects

The blood–brain barrier (BBB) refers basically to especially tight seals between the cells of the blood capillaries in the brain, blocking the movement of many blood-borne substances into the brain tissue.Blood capillaries are composed of thin endothelial cells curled into tubes, like crepes. In most places, they are fairly leaky, with gaps between the cells that let water and dissolved matter pass from the bloodstream into the surrounding tissue. The gaps are called intercellular clefts (see the third label from the top).In the brain, however—for the extra protection of the vital and irreplaceable neurons—these clefts are sealed off. Certain supporting cells of the developing brain called astrocytes (green cell below) send out long tentacles that touch the blood capillaries with their perivascular feet. They secrete a signal that makes the endothelial cells grow closer together and form tight junctions (see bottom label above).Some textbooks and online images give the impression, or explicitly state, that the BBB consists of these perivascular feet themselves wrapped around the capillaries. That’s incorrect; they do not completely enwrap the capillaries, and do not compose the BBB but only stimulate its formation.As for what the BBB looks like, this requires special microscopic imaging techniques. With the aid of fluorescent tissue-specific dyes, the image below shows blood capillaries (the black channels) and the blood-brain barrier (fluorescent green) separating the blood (not seen) from the surrounding brain tissue cells (red).Image credit: The Blood-Brain BarrierThe BBB ensures that anything passing from blood to brain has to pass through the cytoplasm of the endothelial cells, and not between them. This gives the endothelial cells the ability to accept, reject, or modify anything trying to get to the nerve cells. Endothelial cells are much more selective than the clefts between them. They exclude antibodies, other blood-borne proteins, toxins, and so forth, while allowing such vital materials as water, glucose, amino acids, electrolytes, oxygen, and carbon dioxide to pass through.Alcohol, caffeine, nicotine, anesthetics, and other materials not natural to the body can also get through, which is why some babies are born with fetal alcohol syndrome and other drug addictions. Metastasizing cancer cells have a way of breaking down the blood-brain barrier so they can invade the brain tissue.Unfortunately, the BBB doesn’t let medications such as antibiotics and cancer drugs through, so while it normally protects the brain, it’s an obstacle to the delivery of many medications. One of the great frustrations of pharmaceutical research is that drugs can be developed that work great in tissue cultures in the laboratory, but cannot get through the BBB to do any good for living patients. This is why chemotherapy is not generally an option for brain cancers. One of the major areas of drug development is designing drugs so they can pass the BBB.