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A person is suing TGI Friday's for false advertising regarding their bagged "Potato Skins" snacks. Part of the claim is that potato skins are associated with healthy eating, which makes the snack stand out among other bagged, crisp snacks.

The interesting claim is that:

The Idaho Potato Commission and others inside and outside the industry have associated potato skins with healthy eating since they started appearing on restaurant menus a half-century ago.

Does the Idaho Potato Commission associate potato skins with healthy eating?

What I'm assuming here is that "potato skins" is referring to the scooped potato halves filled with cheese, bacon, and other things, much like TGI Friday's in-restaurant appetizer.

Doctor Potato says you should be eating the skin of the potato because that’s where most of the nutrients come from.

Should I Be Eating The Skin Of The Potato?
...

Yes. Eat the skin to capture all the natural nutrition of a russet potato. The potato skin has more nutrients than the interior of the potato. It has lots of fiber, about half of a medium potato’s fiber is from the skin.

Baked Idaho® Potato with salsa makes for a low calorie healthy lunch, try it!

Doctor Potato is a character featured prominently on the Idaho Potato Commission website.

Dr. Potato isn't a real doctor but a team of potato experts ready to answer all your potato questions.

Have a question? Dr. Potato will be sure to get your question answered within a week.

Q: Does the Idaho Potato Commission associate potato skins with healthy eating?

Yes. The Idaho Potato Commission does this now.

In several postings they are responsible for they this:

Kids Menus - Healthful Tips

Fries are always a kid’s favorite. One suggestion that keeps these on the menu but makes them healthier is to cut the potato portion costs but fill out the plate by adding nutritious dipping sauces such as fresh tomato salsa. Another crowd favorite, especially in casual dining situations, is a baked potato skin with smaller quantities of fillings.

History of Potato Skins on the Menu

Idaho® Potatoes and Chemicals

Q: Can you tell me if the skins of Idaho potatoes absorb the chemical sprays that might be used on them?

Leaving the Skins on Potato Salad

Q: Is there any reason the skins cannot be left on a potato when making potato salad?

A: There’s no reason at all, so my advice is to leave the skins on. The skin on a potato adds a nice texture and flavor to the salad and it’s also the healthiest part. We have several potato salad recipes with the skins intact. This link shows off traditional, classics with a twist, even fried.

Should I Be Eating The Skin Of The Potato?

Yes. Eat the skin to capture all the natural nutrition of a russet potato. The potato skin has more nutrients than the interior of the potato. It has lots of fiber, about half of a medium potato’s fiber is from the skin.
Baked Idaho® Potato with salsa makes for a low calorie healthy lunch, try it!

The following is just for SE fun, in case you do not want to know: Reading the complaint from the law suit surely adds hilariousness on several levels.

"The presence of potato skins imparts a further value in the eyes of reasonable consumers,” the complaint states.

Is it actually the case that potato skins are 'healthy'?

This is quite stupid advice in general. Any 'reasonable consumer' believing this as phrased is being seriously misled.

Eating the skins of a potato increases the toxin load. Usually by an order of magnitude. And often beyond safety margins. The only other 'nutrients' in the skin – which are found in higher amounts than in the flesh – are fibre (says the IPC!) and iron, since 'most of the nutrients' are quite obviously in the big flesh of the tubers (PDF).

The skin is where this solanaceae plant stores most of its toxins, like chaconine and solanine:

Solanine poisoning is primarily displayed by gastrointestinal and neurological disorders. Symptoms include nausea, diarrhea, vomiting, stomach cramps, burning of the throat, cardiac dysrhythmia, nightmares, headache, dizziness, itching, eczema, thyroid problems, and inflammation and pain in the joints. In more severe cases, hallucinations, loss of sensation, paralysis, fever, jaundice, dilated pupils, hypothermia, and death have been reported.
Ingestion of solanine in moderate amounts can cause death.

One study suggests that doses of 2–5 mg/kg of body weight can cause toxic symptoms, and doses of 3–6 mg/kg of body weight can be fatal.
Symptoms usually occur 8 to 12 hours after ingestion, but may occur as rapidly as 10 minutes after eating high-solanine foods.

But potatoes also contain solanidine, nicotine, β-solanine, γ-solanine, β-chaconine, γ-chaconine, leptinines, leptines, solasodine, solanocapsine, demissine, calystegines, commersonine, solamargine, solasonine…

Asano et al. (1997) found that calystergines in S. tuberosum strongly inhibited mammalian liver b-glucosidaseand a-galactosidase activity.

In some cultivars, levels of a-solanine (+ a-chaconine) in potato disks increased 4-fold both under light and in the dark (Bergenstrahle et al. 1992). Recently, steroidal glycoalkaloid biosynthesis was found not to be associated with chlorophyll biosynthesis in potato tubers (Edwards et al. 1998). Both low (< 5°C) and high (> 15°C) temperature stimulated the accumulation of steroidal glycoalkaloids in potato tubers (Friedman and McDonald 1997).
_{Zhenbang Chen & A Raymond Miller: "Steroidal Alkaloids in Solanaceaous Vegetable Crops", Horticultural Reviews, Vol 25, 2001, p171–196. (DOI)}

These alkaloids are poorly absorbed but tend to accumulate in a body as they are also poorly eliminated.

The safety precautions on international Wikipedia pages, like Spanish:

In children poisoning is a frequent cause of death.

The clinical evolution of the affected person depends on the type of poisoning, which can be acute, subacute or chronic.

Acute form

Caused by the ingestion of high amounts of a-solanine; in experimental animals a gastrointestinal syndrome associated with diarrhoea appears. In humans with high amounts of solanine poisoning the symptomatological picture corresponds to gastrointestinal disorders. These symptoms have also been described in cattle. Solanin has haemolytic action and in severe cases can lead to stroke.

Subacute form

Resulting from the ingestion of small doses of these glycoalkaloids, is associated with enteric lesions once the toxic has been absorbed. In this form the symptoms of neurological character stand out because they appear relevant signs of motor incordination, facilitating falls, nystagmus, convulsions and opisthotonos, complemented in some cases by cardiac irregularities, hemolysis and sometimes diarrhea. The blockage of nerve signals can lead to death in one or two days, in the most extreme cases.

Chronic form

You may observe signs including edema of the breast and forelimbs, anemia, renal failure, yellow mucous membranes, constipation and abdominal distension.

Also the pages for Italian, Portuguese, Dutch which say: "best to remove the skins".

Unless it's a very young potato from a breeding target of very low alkaloid content that was stored perfectly and shortly, undamaged (and low solanine requires more pesticides) then the skins should always be removed quite graciously.

The toxins are always present, concentrated in the skin. Present in harmful concentrations even before taste buds can detect them or greening might indicate unreliably the same to the eyes. Not removing the skin is idiotic.

The cultivars differ widely, already during grow and harvest, but post-harvest the toxin levels vary even greater. The generalised advice of "eating the skin is good for you" is indefensible in this phrasing.

The IPC's "Dr Potato" seems to know nothing about alkaloids. But the IPC itself does offer one document (PDF) that mentions alkaloids:

glycoalkaloids: Naturally occurring chemicals found in potatoes that may cause illness in humans at high levels (primary compounds are α-solanine and α-chaconine). Potato cultivars/varieties are bred for low levels of glycoalkaloids. Levels may increase if tubers are exposed to light during the growing period, harvest, storage or transportation.

In other words: alkaloids may increase at any time and a consumer has no reliable way of knowing how high the alkaloid content of a tater on his plate will be. Apart from that the IPC fails to mention that temperatures and moisture, as well as simply time, also tend to increase the alkaloid content. Reality dictates a modification to the euphemistic description the IPC presents: "Naturally occurring chemicals found in potatoes that certainly will cause illness in humans at high levels".

Tjeert T. Mensinga et al.: "Potato glycoalkaloids and adverse effects in humans: an ascending dose study", Regulatory Toxicology and Pharmacology
Volume 41, Issue 1, February 2005, Pages 66-72. DOI

An analysis of the literature proves that GAs, the natural components of potato, clearly are toxic to both humans and animals. The concentration of GAs in potatoes destined for human consumption in many countries, 200 mg kg21 – which is generally accepted as a ‘total alkaloid taste standard’ – has a ‘zero’ safety threshold. One reason for this conclusion is best stated by the words of Parnell et al. 29, in a paper published 20 years ago:
‘Many authors have assumed without further evidence that levels below 200 mg/kg are safe. They ignore the fact that the 200 mg/kg (FW) level only relates to acute and/or subacute effects and not to possible chronic effects…’
It is obvious that the existing total alkaloid taste standard should be revised and new guidelines for potato consumers and breeders should be formulated.
_{Yaroslav I. Korpan et al.: "Potato glycoalkaloids: true safety or false sense of security?", Trends in Biotechnology, Volume 22, Issue 3, P147-151, March 01, 2004. DOI}

Even in peeled potatoes the levels of these toxins can be way too high for safety. To issue any general "eat the skins, they are healthy" is not wise:

… 15 different varieties of potato were considered, some of which are among the most cultivated varieties… The potatoes were harvested in the same period and analysed immediately after harvest to evaluate their a-solanine and a-chaconine contents. Then, the potatoes were stored in the dark at room temperature to simulate common storage conditions before similar potatoes would be sold.

The a-solanine content in almost all varieties was higher than the a-chaconine content. … the a-chaconine content increases to alarming levels, which were even beyond the limits of the guard.
_{Valeria Romanucci et al.: "Toxin levels in different variety of potatoes: Alarming contents of a-chaconine", Phytochemistry Letters 16 (2016) 103–107 DOI}

Consider the above a small fraction of the literature that demonstrates again and again how irresponsible the primitive equation "potato skins – vitamins – healthy – eat them" is.

This is summarised by the Federal Institute of Risk Assessment in:

• Old, dried up, green or strongly germinating potatoes, as well as potato peels as snacks consisting mainly of potato peelings, are not suitable for consumption
  


• If consumers want to eat the skin along with the potato, only undamaged, fresh potatoes are fundamentally suited for this purpose


• 
  Small children in particular should not eat unpeeled potatoes
  _{BfR: Solanine in potatoes: Green and strongly germinating potato tubers should be sorted out (2019)}

From a 1996 study, the 'on average' the concentrations in potatoes, and their parts are, in mg/kg:

 Whole potato 10-150
 Peel (outer 10%) 150-1068

Fried potato skins (common in the US) have concentrations from 560-1450 mg/kg.

However, jacket potatoes, and more recently potato skin preparations have a relatively high content of GA; levels in excess of the 200 mg/kg limit (and up to eightfold higher) have been reported for potato skin preparations and potato crisps made from unpeeled potatoes. Moreover, heat processing does not inactivate potato GAs.
_{David B. Smith, JamesG. Roddick and J. Leighton Jone: "Potato glycoalkaloids: Some unanswered questions", Trends in Food Science & Technology 7.4 (1996): 126-31.}

The skins of three medium sized tubers can kill a kid. Incidentally 78 kids were poisoned in 1979 London. The highest dose an individual consumed in a lab setting was up to 1.25 mg/kg until that individual started vomiting…

Available information suggests that the susceptibility of humans to glycoalkaloid poisoning is both high and very variable: oral doses in the range 1–5 mg/kg body weight are marginally to severely toxic to humans whereas 3–6 mg/kg body weight can be lethal.

The narrow margin between toxicity and lethality is obviously of concern. Although serious glyco-alkaloid poisoning of humans is rare, there is a widely held suspicion that mild poisoning is more prevalent than supposed; however, because the symptoms (e.g. abdominal pain, vomiting, diarrhoea) are similar to those of other common gastrointestinal ailments, it is rarely diagnosed or treated.

The widely accepted safety limit for the levels of GA in tubers remains at 200 mg/kg fresh weight - a level that was proposed more than 70 years ago when little information was available concerning subacute and chronic glycoalkaloid toxicity. However, owing to the large and often unpredictable variations in levels of GA, which can arise from differences in variety, locality, season, cultural practices and stressfactors, and the fact that so many aspects of the biochemistry and toxicity of these compounds remain poorly understood, it has been suggested that the limit should be reduced to 60-70 mg/kg (Ref. 27).
_{(Again: Smith 1996)}

Supermarkets do not present their wares in dark and cool rooms. Every hour of a potato in the shelves raises the GA content. The WHO sees up to 100mg/kg GA of fresh weight for the whole tater to be 'normal'.

Only for very fresh and perfectly handled Idaho russet potatoes you may wager that the skins are somewhat edible and probably might contain low enough toxins (Friedman/Dao 1992 DOI), that doesn't make them 'healthy'. For other regions, or for other cultivars, or for other growing and harvesting and storage and processing and (…) this is certainly not the case:

The TGA concentration in the peel of all tested potato cultivars in this study was higher than the limit recommended by FAO/WHO for their food concerns. Moreover, the amount of TGA in the flesh of potato cultivars, that is, SH-5, Diamant, FD 35-36, FD 8-1, FD 40-10, FD 1-8, FD 19-2, and FD 3-9 were lower than the prescribed limits. Therefore, these cultivars are considered safe for human consumption. Furthermore, the dietary intake assessment of selected potato cultivars revealed that cardinal, FD 35-36, FD 8-3, and FD 3-9 cultivars possessed higher amount of TGA than the safe value but their flesh contains well below MPI.
_{(Abdl Aziz et al.: "Glycoalkaloids (α‐Chaconine and α‐Solanine) Contents of Selected Pakistani Potato Cultivars and Their Dietary Intake Assessment", Food Science, Volume 77, Issue 3, March 2012, Pages T58-T61, online)}

To get practical with Swedish potatoes (albeit with the much too high 200mg/kg fresh produce level):

A no-observed-effect level has not been established, but 200mg GA/kg potato has been most frequently cited in the literature as a 'safe' (non-toxic) concentration. Based on the estimated average daily intake of 300 g potato (Sweden) this would roughly correspond to the dose 1mg GA/kg body weight, which could be considered to be the ADI for an adult. As can be seen a safety factor of 2 (based on LOEL) is incorporated in such calculations.

Given the fact that higher than average consumption often occurs as well as the fact that GA levels can occasionally exceed 200mg/kg potato (about 9% of the early potato varieties in Sweden) the health--safety margin for 'solanine' cannot be considered satisfactory.

In contrast, in the risk assessment of, for example, pesticide residues in potato a safety factor of 100 (extrapolation from animal studies) is most often used. The amounts of pesticides present in an average portion of potato (Sweden) constitute only a fraction of the ADI.

This comparison illustrates the discrepancy that exists between the risk assessment of synthetic chemicals and naturally occurring toxins.
_{P. Slanina: "Solanine (Glycoalkaloids) In Potatoes: Toxicological Evaluation", Fd Chem. Toxic. Vol. 28, No. 11, Pp. 759-761, 1990. (PDF)}

Compare that to the BfR NOAEL below and realize that Swedes had even peeled potatoes regularly exceeded that level on average by >100%.

Or a more recent sample from the US:

…the glycoalkaloid content of four skins we obtained from four restaurants ranged from 56.3 to 203.0 mg/kg of original product.

sample  total (α-chaconine + α-solanine ) 
Atlantic potato peel 83.8 
Atlantic potato flesh 36.5 
Russet Narkota potato peel 425
Russet Norkota potato flesh 6.4
Dark Red Norland potato peel 1264
Dark Red Norland potato flesh 22.1
Snowden potato peel 3526
Snowden potato flesh 591
Russet whole potatoes 100
White whole potatoes 43.5
Benji whole potatoes 98.3
Lenape whole potatoes 629

processed original product
 total GA 
skins, A 56.3 
skins, B 67.6 
skins, C 188.4 
skins, D 203.0 

None of the listed wet whole potatoes exceeded 200 mg of total glycoalkaloids/kg of potatoes. However, this was not the case for potato peel. The values for three wet peel samples (Atlantic, Dark Red Norland, and Russet Norkota) are <200 mg/kg and those for the other five, >200 mg/kg.
High levels of glycoalkaloids in potato skins may be a concern for commercial products that have high skin/flesh ratios, for example, potatoes from which the flesh has been mostly removed and the skin is used to scoop up condiments such as salsa. Peel from potato-processing plant wastes may also be a concern if the peel is not thoroughly mixed with other waste streams.
_{Mendel Friedman: "Potato Glycoalkaloids and Metabolites:  Roles in the Plant and in the Diet", Journal of Agricultural and Food Chemistry, 2006, 54 (23), pp 8655–8681 (DOI)}

The level of nutritional stupidity and stubbornness seems at a constant level in America, however simple and accessible the language used:

"People think the skin is the nutritious part of the potatoes. Glycoalkaloids are a natural constituent of the potatoes. And it doesn't have to turn green to have glycoalkaloids. They can still synthesize glycoalkaloids without exposure to light,"
Glycoalkaloids can range from two to 30 milligrams per 100 grams in a single potato. Amounts, however, double and triple when potatoes turn green, usually upon exposure to light.

In previous studies, researchers found that the average glycoalkaloid content in baked potato peels was 20 milligrams per 100 grams of fresh weight, the upper limit considered safe. When fried, however, the content of the chemical more than doubled to 44 milligrams per 100 grams.

According to Mondy's report, the high glycoalkaloid content of fried potato peels could cause possible toxicity. "These findings are important because fried potato peels have become a popular snack."

However, if you peel the potato, the level of compound is much reduced. "You can get rid of about 90% of the glycoalkaloid," Gosselin said.
_{Rose Dosti: "Toxicity of Potato Skins Becomes a Hot Issue : Natural Chemicals in Peels Can Pose Problems If Eaten in Huge Quantities", Los Angeles Times, June 25, 1987.}

A dissertation on developing analysis methods for GA content used German market bought potatoes from conventional and organically farmed cultivars. Result: the flesh of all fruits was toxicologically unproblematic, with one exception; while the skins were all completely unfit for human consumption with again two exceptions that posed moderate risk.
_{(Melanie Distl: "Entwicklung von Nachweisverfahren für toxische Solanum-Glykoalkaloide und ihre Anwendung in Kartoffeln und daraus zubereiteten Produkten", Dissertation, Heidelberg, 2007, PDF.)}

Potato skins are a toxic waste product sold to stupid customers:

Though potato skins originally served as a clever way to repurpose food scraps, they’ve now been turned into a commodity all their own.

To re-iterate: the toxicological expert opinion is that the in 1924 arbitrarily set upper limit of 200 mg/kg is too high, that the FAO/WHO limit of 100 mg/kg is very probably also too high, and the proper limit should be at 50–60 mg/kg for fresh produce. As should be clear from the findings above: all real world data suggest that no tested US potato peel product can be safely assumed to be below that level of concern. Often not even for the old and unscientific highest level.

Consumers insisting on 'potato peels are healthy' may have already eaten too much of them to be now unable to properly discuss the matter at hand: This class of compounds is a neuroteratogen.

Studies have reported various ranges in the total glycoalkaloid levels of 8.4–222.6 mg 100g^-1 in dry peels and 0.5–59.2 mg100g^-1 in dry flesh, 17.4–549.7 mg 100g^-1 in dry peel, 64.2 mg100g^-1 in dry boiled flesh, and 58.5–534.2 mg100g^-1 1 in dry peel and from 0.7–46.6 mg100g^-1 in dry flesh.

 mg/kg, fresh weight (200mg threshold)
Normal tuber 10-150
- Skin (2-3% of tuber) 300-640
- Peel (10-12% of tuber) 150-1070
- Flesh 12-100 

The occurrence of the glycoalkaloids in potato and potato products cannot be wished away. Glycoalkaloid intake through consumption should also consider the effects that various processing and postharvest handling practices may have on the levels of glycoalkaloids. There is need for assessment of glycoalkaloid occurrence in potato and potato products in growing and consuming countries. intake levels need to be established to guide policy makers.
_{Duke Gekonge Omayio et al.: "A Review of Occurrence of Glycoalkaloids in Potato and Potato Products", Current Research in Nutrition and Food Science Vol. 4(3), 195-202 (2016) (PDF).}

The FDA DB Poisonous Plants reports:

In recent outbreak of solanine poisoning […] a hotel proprietor and his family of four ate potatoes baked in their jackets for supper on three successive Sunday evenings. All who ate the skins were ill on each occasion with vomiting, diarrhoea, and abdominal pain. The symptoms were delayed some eight hours and recovery was complete in 24 hours. The hotel proprietor, who ate only the flesh of the potatoes each time, remained well.

Another case of a whole family being poisoned from November 2015: after the consumption of legally bought supermarket potatoes and preparing them as baked potatoes with skin. The family didn't notice any bitter taste when making a puree from those taters but a bitter taste when making a potato salad from them.

The German BfR used this case to re-iterate the 200 mg/kg for fresh produce is likely too high and that consumers should aim to stay below a NOAEL (No-Observed Adverse Effect Level) of 0.5 mg/kg/day (kg here for human body weight). –– And that snacks made from potato skins should not be consumed!

(DOI: 10.17590/20180423-085250. Another case report from 2011 with wedges with skin, 125g of finished product being poisonous PDF. And one from HongKong, 2015, PDF)

So, if you see anywhere on the net a statement like "Doctor Potato says you should be eating the skin of the potato because that’s where most of the nutrients come from", then now you know that nothing in that statement is true.

Peeling reduces the quantity of glycoalkaloids in potatoes since 30 to 80% of the glycoalkaloids are found in the outer peel. Baked and fried potato peels are a major source of large quantities of a-chaconine and a-solanine in the diet.

Poisoning resulting from ingesting potatoes containing high levels of glycoalkaloids has been demonstrated in a number of case studies. Symptoms, which generally occur 8 to 12 hours after ingestion, include gastrointestinal disturbances and neurological disorders. One study analyzing case reports of poisoning determined that glycoalkaloid doses of 2 to 5 mg/kg (0.0023- 0.0058 mmol/kg) induce toxic symptoms in humans, and doses of 3 to 6 mg/kg (0.0035-0.007 mmol/kg) are fatal.

Fried potato peels are a source of large quantities of a-chaconine and a-solanine; one study indicated that fried potato peels had a-chaconine plus a-solanine levels of 1.4 to 1.5 mg/g potato peel (Bushway and Ponnampalam, 1981), which is seven times the recommended upper safety limit (0.2 mg/g potato) (Beier, 1990). Another study found that combined a-chaconine and a-solanine levels in baked or fried peels of commercial potato varieties ranged from 0.02 to 1.1 mg/g potato peel and 0.03 to 1.6 mg/g potato peel, respectively (Bushway et al., 1983).
_{Raymond Tice for National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, February 1998. (PDF)}

The glycoalkaloid a-chaconine is considered more toxic than a-solanine. Temporary gastrointestinal problems have been reported for some individuals eating potatoes that contained 3-10 mg/100g glycoalkaloids. Most of the laboratory studies on glycoalkaloids have been done on animals. The only comprehensive laboratory experiment on solanine toxicity to humans showed that 2 mg of glycoalkaloid per kg body weight produced classic symptoms of poisoning. An 80 kg person who ate 100 g of peels from the potatoes mentioned above with 180 mg solanine/100g peel would probably experience symptoms of solanine toxicity.
_{Marita Cantwell: "A Review of Important Facts about Potato Glycoalkaloids", Perishables Handling Newsletter Issue No. 87, August 1996 (PDF)}

To all those poisoning their kids needlessly with potato skins and upvoting obsolete comments: the gist of these fun facts of the day above is still: yes, the Idaho Potato Commission claims irrational things, and yes, "potato skins are healthy" is one embodiment of careless stupidity that still looks for a match. For a small amount of increased fibre and vitamins you always increase the toxic load drastically. Skins can be edible, but their measly fibre content compared to their toxic content will not make them any kind of "healthy". Eat the fleshy part and be good.