The arithmetic of yogurt

I’ve been recently discussing how and why we make yogurt with two strains of Lactobacillus reuteri to augment our oxytocin status and thereby enjoy additional weight loss, reduce appetite, grow muscle, increase bone density, obtain younger more supple skin with increased collagen, accelerate healing, increase testosterone in males, etc.

I’ve received a considerable amount of feedback from people who have been making L. reuteri yogurt and consuming 1/2 cup per day: reduced facial wrinkles, smoother skin, dramatic reduction or elimination of appetite, increased energy, better mood, reduced bruising (specifically senile purpora), receding surface veins, increased libido—some fairly dramatic results.

But I’ve also been hearing comments like “I made the yogurt and let it ferment for 7 hours and it was still liquid.” Or “I fermented my yogurt for 12 hours, then put it in the refrigerator.”

Too little time allowed for yogurt to ferment will impair your results. The doubling time of L. reuteri, i.e., the amount of time required for, say, 1000 microorganisms to become 2000 microorganisms, is around 3 hours in the presence of prebiotic fibers. (Bacterial reproduction—doubling time—is shortened by fermenting yogurt by adding prebiotic fibers such as inulin or raw potato starch or sugar.) This means 8 doublings over the course of 24 hours.

So let’s say that you start your yogurt-making experience with one billion microorganisms (“CFUs”) of L. reuteri. Three hours later, you will have two billion. Six hours later, four billion. Nine hours later, eight billion, and so on.

You let fermentation proceed for 24 hours and now have 256 billion. (We are not accounting for bacterial death for simplicity. And, anyway, L. reuteri does not have to be alive to exert oxytocin release from the hypothalamus.) But look at the numbers after the initial 24 hours:

27 hours: 512 billion
30 hours: 1.26 trillion
33 hours: 2.52 trillion
36 hours: 5.04 trillion

Get the idea? At 36 hours, the initial one billion microorganisms have ballooned to over 5 trillion, far better than, say, the 8 billion present after only 12 hours. Such is the magic of exponential expansion of numbers. The most important period of fermentation to generate substantial bacterial counts is not the initial period, but the later periods as doubling allows exponential growth to very substantial numbers. This cannot go on forever, of course, limited by competition for available nutrients, such as the prebiotic fiber we add at the beginning, as well as increasing separation into curds and whey.

Longer fermentation time also allows production of more lactic acid that reduces yogurt’s pH, making it more acidic, more tart. Beyond the gustatory aspect, an acidic pH further denatures, or breaks down, the casein beta A1 protein, the potentially immunogenic protein of North American dairy. It also increases butyrate content produced by L. reuteri, the short-chain fatty acid believed to account for many of the beneficial effects of bowel flora such as reduced blood pressure, reduced insulin resistance, reduced triglycerides, and perhaps the mind-emotional effects, effects outside of the oxytocin-boosting benefits.

Bottom line: Allow fermentation to proceed for a minimum of 24 hours, preferably 30-36 hours, to extract maximum benefit. This is not so much about yogurt but about maximizing the population of L. reuteri and its metabolites. And the end-product is far richer and flavorful than anything you can buy at the grocery store.

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