Oral rehydration therapy at home #2

Following up my last post on oral rehydration therapy, it was pointed out to me that coconut water is a rich source of potassium. So much so that it can be used to make an alternate home recipe for Oral Rehydration Solution. The recipe, illustrated above, is:

  • 3 metric cups (750 ml) of water
  • 1 metric cup (250 ml) of coconut water
  • 8 metric teaspoons (40 ml) of lemon or lime juice, as a source of citrate
  • 1 metric teaspoon (5 ml) of honey, to supply additional glucose
  • ½ metric teaspoon of salt, to supply additional chloride and sodium
  • ½ metric teaspoon of baking soda (sodium bicarbonate), to supply additional sodium, and as a way of neutralising the acidity in the lemon or lime juice

Advertisements

Oral rehydration therapy at home

Oral rehydration therapy is one of the most cost-effective lifesavers in the history of medicine. It stops people dying from cholera and other diarrheal diseases. It works because of the sodium-glucose co-transport mechanism in the intestines, discovered by Robert K. Crane around 1960.

The WHO has guidelines for Oral Rehydration Solution, and the recipe pictured at the top of this post is my attempt to approximate these guidelines using ordinary kitchen ingredients and easy measurements (doing a computerised search through the space of valid options). The mix actually tastes OK too. The recipe is:

  • 1 litre of water
  • 8 metric teaspoons (40 ml) of lemon or lime juice, as a source of citrate (10 millimoles, by my calculation)
  • 3 metric teaspoons (15 ml) of honey, as a source of glucose and other sugars (90 millimoles)
  • 1 metric teaspoon (5 ml) of cream of tartar (potassium bitartrate), as a source of potassium (19 millimoles)
  • ¾ metric teaspoon of salt, as a source of chloride (73 millimoles) and sodium
  • ¼ metric teaspoon of baking soda (sodium bicarbonate), as an additional source of sodium (giving 87 millimoles in total), and as a way of neutralising the acidity in the lemon or lime juice

The total osmolarity here is just under 300 millimoles, which is above the optimum of 245, but under the upper limit of 310. The specific WHO criteria for glucose (between the sodium level and 111 millimoles), sodium (60–90), potassium (15–25), citrate (8–12) and chloride (50–80) are also satisfied.

Possible substitutions are 13.5 grams of glucose powder for the honey and 2.1 grams of citric acid monohydrate for the lemon juice. The three other ingredients can also be replaced by ½ teaspoon “lite salt” (which provides sodium and potassium), ¼ teaspoon ordinary salt, and ½ teaspoon baking soda.


Angélique du Coudray, pioneer midwife


Angélique du Coudray

Angélique du Coudray (c. 1714–1794) was a pioneering French midwife. In 1759 she published a midwifery textbook, Abrégé de l’art des accouchements. Her introduction notes the fact that incompetence or lack of care can lead to the death of both mother and child, and continues with a politico-religious imperative: “Ignorons-nous que ces deux viâimes étoient chères aux yeux de Dieu, utiles à leur famille, & nécessaires à l’État? C’étoit un dépôt qui nous avoit été confié. Pouvons-nous, en les sacrifiant à un vil intérêt, ne pas trembler sur le compte exact que nous en rendrons un jour à celui qui leur avoit donné l’être?” (“Do we not know that these two lives were dear to the eyes of God, useful to their families, and necessary to the State? They were a deposit which was entrusted to us. Can we, if we sacrifice them to a vile interest, not tremble at the exact account that we shall one day render to Him who gave them to be?”).

To avoid such deaths, du Coudray explains proper prenatal care, and provides instruction on both normal deliveries and a range of common obstetric problems.


Illustration of a normal delivery, from the 1777 edition of Abrégé de l’art des accouchements

Also in 1759, Angélique du Coudray was commissioned by King Louis XV to tour the country training midwives, in the hope of reducing perinatal mortality. She personally trained thousands of midwives, many of whom went on to train others. Her training course was assisted not only by her book, but also by her Machine, a pioneering lifesize obstetric simulator. The Machine included realistic internal structure, such as bones and ligaments, and could be used to practice delivery of a baby in a range of different positions, while giving the trainee midwife a feel for the forces involved.


Angélique du Coudray’s Machine (photo: Ji-Elle)


New antibiotics urgently needed

The World Health Organization (WHO) has recently released a list of bacteria for which new antibiotics are urgently needed. They are hoping for new research and development, especially on multi-drug-resistant gram-negative bacteria. The list is divided into three priority categories:

CRITICAL PRIORITY

HIGH Priority

Medium Priority


Homeopathy

Homeopathy is an alternative medicine based, in large part, on extremely dilute solutions of illness-producing agents. For example, diluted coffee is used to treat insomnia.

Given the levels of dilution used, and the fact that 18 grams of water (about one tablespoon) contains about 6 × 1023 molecules, this means that homeopathic medicines generally contain zero molecules of the active ingredient – that is, they are generally plain water. The 10:23 anti-homeopathy campaign is based on that idea:

Last year, the Australian National Health and Medical Research Council (NHMRC) completed a review of the effectiveness of homeopathy, concluding that there are no health conditions for which there is reliable evidence that homeopathy is effective because no good-quality, well-designed studies with enough participants for a meaningful result reported either that homeopathy caused greater health improvements than placebo, or caused health improvements equal to those of another treatment.

See also a blog post by the report chair here, or listen to this interview with Edzard Ernst, former Professor of Complementary Medicine at Exeter. XKCD makes an economic argument about effectiveness:


Mercury and formaldehyde in vaccines?

The anti-vax community runs regular scare campaigns regarding “toxins in vaccines.” Mercury and formaldehyde are the two most often mentioned. Mercury occurs in the form of the antibacterial thiomersal (thimerosal), but not in vaccines routinely administered to children. Thiomersal is present in multi-dose vials (not in single-use vials) of influenza vaccine, typically at a level of 25 micrograms (0.025 milligrams) per dose. For comparison, though, the normal mercury intake is about 2410 micrograms (2.41 milligrams) per year, so an annual “flu shot” adds very little extra. And even that exaggerates the risk, because thiomersal breaks down into ethylmercury, which is less dangerous than other forms.

Formaldehyde, though toxic in moderate to large quantities, is naturally produced and consumed as part of human metabolism, with a turnover of about 50 grams of formaldehyde per day for a person weighing 50 kg. Formaldehyde occurs naturally in blood at levels of about 2.6 milligrams per litre. Even for a 3.5 kg newborn baby (with 85 mL/kg of blood), that comes to 0.77 milligrams of formaldehyde (and there’s more in body tissue). Vaccines contain at most 100 micrograms (0.1 milligrams) of formaldehyde, and so add very little to the blood (and that is very quickly eliminated). That’s even more true for older children, with their much greater blood volume.

Part of the problem here, I suspect, is widespread confusion between grams, milligrams, and micrograms. At the other end, of course, some people also have problems in economics with understanding the difference between millions, billions, and trillions.


Circulation: William Harvey’s Revolutionary Idea (a review)


Circulation by Thomas Wright

I recently read Circulation: William Harvey’s Revolutionary Idea by Thomas Wright. This interesting biography of William Harvey concentrates on his discovery of the circulation of the blood through the body, and his publication of Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus in 1628. The historical and social context of Harvey’s work is described particularly well.


William Harvey

Harvey’s idea had the potential to revolutionise medicine, doing for biology what Galileo had done for astronomy. Sadly, although Harvey’s work undermined the basis for pointless treatments like bloodletting, the respect accorded to ancient Greek medicine kept such treatments alive for centuries after they should have ceased.


An illustration from Harvey’s book

This well-written book is well worth reading, and of interest to students of science, history, and medicine (although the descriptions of live dogs being dissected are a little disconcerting). It won the 2012 Wellcome Trust Book Prize.


Circulation by Thomas Wright: 3.5 stars