Hacker News Reader

noisy channels have information capacity.

reports are that the loss of sense of smell and taste are severe, sometimes total. things 'taste weird' or have no taste at all. it doesn't matter what the person's sense of smell was before - the magnitude of change reported by a noticeable amount of individuals in a geotemporal cluster is enough to trigger an alert. the key is 'noticeable amount', so you measure background noise first.

I’m covid19-positive and I don’t have any impairment in my ability to smell nor do I recall having such impairment in recent time. The most salient symptoms for me have been GI problems.

"[The doctors] concluded that roughly 80% of the people who lost their sense of smell would test positive for the coronavirus, and that somewhere between 30% and 60% of those who had tested positive for the virus had also lost their sense of smell."

covid19? --> ~30-60% chance of loss of smell

loss of smell? --> ~80% chance of covid19 [in the data they collected]

Other things can cause loss of sense of smell too, long before covid19, so it would have to be way more prevalent in covid than any other cause for that 80% to make sense. If so, that's interesting.

Is this loss of sense of smell permanent? That sounds very scary.

Olfactory neurons are somewhat notable for their ability to regenerate.

Does the virus damage olfactory neurons, or does it cause loss of smell via different mechanism?

For what it's worth, my grandma lost her sense of smell permanently in her 30s after a car crash. Unfortunately, now she can't tell if the food is burning.

Interesting. I didn’t know GI symptoms were significant until now

https://labblog.uofmhealth.org/lab-report/are-digestive-issu...

Your point about the fallibility of self-reporting sense of smell is valid, but please don't talk about real and serious food sensitivities in such a flippant way. They aren't subjective in the same way as smell, and there are medical tests available and widely used to verify intolerances (such as the hydrogen breath test for lactose intolerance, or the intestinal biopsy for Celiac disease).

For testing by sense of smell to work with any degree of certainty, there would have to be similar tests beyond self-reporting.

There are plenty of people with real allergies and real intolerances. There are also plenty of people who don't have any allergy or intolerance and convince themselves they do. Those people make it harder for those that have real allergies and intolerances.

Alternatively, they are people that pay attention to their bodies and have intolerances that aren't strong enough to warrant a medical diagnosis but still make them feel shitty.

I'm also skeptical of the idea that they make it harder for people with "real" intolerances - in the gluten example, there's been an explosion of GF foods, products, and menu signage ever since "gluten intolerance" became a familiar phrase.

> I'm also skeptical of the idea that they make it harder for people with "real" intolerances - in the gluten example, there's been an explosion of GF foods, products, and menu signage ever since "gluten intolerance" became a familiar phrase.

Per celiac relatives, the gluten free "fad" has helped in the creation and availability of a lot more prepackaged foods in stores, but hurt in that a lot of restaurants don't take it fully seriously and do things in ways that result in cross-contamination, so there's more crap to wade through to find the truly safe gluten-free places at which to eat out.

To me it seems like the main way they "make it harder" is that _other people_ like to talk about them a lot and might be inclined to take intolerances in general (including diagnosed ones) less seriously. Which I don't really understand -- it doesn't hurt me for someone else to avoid eating something, why should I fault them for that?

How?

I am not being flippant. Rather I was thinking of this review study of "lactose intolerance" that I've read recently (couple of days ago):

Allaying Fears and Fallacies about Lactose Intolerance

https://www.sciencedirect.com/science/article/abs/pii/S00028...

Abstract

Public awareness and misunderstandings of lactose intolerance are at an all-time high. Many people erroneously believe they are lactose intolerant or develop gastrointestinal symptoms after intake of lactose. Consequently, lactose-containing foods such as milk and other dairy foods may be eliminated unnecessarily from the diet. Because these foods are a major source of calcium, low intake of them can compromise calcium nutriture. This, in turn, can increase the risk of major chronic diseases such as osteoporosis (porous bones) and hypertension. This review is intended to help dietetics professionals alleviate clients' fears about lactose intolerance and recommend dietary strategies to improve tolerance to lactose. Scientific findings indicate that the prevalence of lactose intolerance is grossly overestimated. Other physiologic and psychologic factors can contribute to gastrointestinal symptoms that mimic lactose intolerance. Scientific findings also indicate that people with laboratory-confirmed low levels of the enzyme lactase can consume 1 serving of milk with a meal or 2 servings of milk per day in divided doses at breakfast and dinner without experiencing symptoms. Several dietary strategies are available to help lactose maldigesters include milk and other dairy foods in their diet without experiencing symptoms.

The full study cites results from breath hydrogen tests to support its claim that "the prevalence of lactose intolerance is grossly overestimated" (as stated in the abstract, above). In particular:

A diagnose of lactose maldigestion [by an increase in breath hydrogen concentration of 20 ppm or more above the baseline value measured by a breath hydrogen test] does not predict the occurrence of symptoms of intolerance (12, 13, 15, 22, 28, 30). Nor can symptoms that follow lactose or milk intake be used to diagnose low lactase levels or lactose maldigestion (28). Intolerance symptoms after a lactose load have been demonstrated to occur in lactose maldigesters and lactose digesters (28).

Or, in other words (citing from the paper):

There is no clear correlation between lactose maldigestion, lactose intolerance, and milk intolerance. This may be explained by the subjectiveness of symptoms and the quantity of lactose or milk required to demonstrate symptoms. Strong beliefs may contribute to lactose intolerance; that is, persons who believe they are lactose intolerant may experience symptoms (12,30). Johnson et al (12) reported that when 45 lactase-deficient African-Americans were fed either a lactose-containing milk or lactose-hydrolyzed milk under boudle-blind conditions, on third of the subjects experienced some minor intolerance to both types of milk. The subjects' symptoms were not due to the lactose content of milk, but perhaps to social and cultural attitudes that influenced their ability to tolerate milk (12). In a more recent double-blind investigation, Vesa et al (3) found that one half of lactose maldigesters reported symptoms after consuming a lactose-free milk or a greater level of symptoms after intake of smaller rather than larger intakes of lactose. The symptomes were due, therefore, to factors other than lactose intake.

I note that this is one study and rather dated, but I just happened to stumble upon it while looking for something else. There may be newer studies in the literature that contradict this one's findings.

Edit: also, I used the term "gluten intolerance", not "coeliac disease". Please don't accuse me of being flippant about coeliac disease when I did no such thing.

> I am skeptical. A test based on the sense of smell would have a very high amount of noise. There is no good, concrete measure of a person's sense of smell.

Parents with young children in diapers might disagree. I can think of one test that occurs consistently and is easy to validate.

(Joking aside, I do think about the fact that I can detect soiled diapers as evidence that I can still smell just fine!)