# Does filtered milk contain iodine? **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2018, 11:25pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529 "2018-11-14T23:25:07Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![sara20](https://avatars.discourse-cdn.com/v4/letter/s/e79b87/32.png) [@sara20](https://boards.straightdope.com/u/sara20)\ **Post date:** [November 14, 2018, 11:25pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/1 "2018-11-14T23:25:07Z")
I drink fairlife milk which is “ultra filtered” so the lactose is removed, but milk is the main source of iodine for most people and I have been worried I am not getting enough iodine. I am wondering if the filtering process removes the iodine? I contacted the company who basically told me they don’t know, so I am wondering if any chemistry majors here can figure it out. ---
**Author:** ![nearwildheaven](https://avatars.discourse-cdn.com/v4/letter/n/90db22/32.png) [@nearwildheaven](https://boards.straightdope.com/u/nearwildheaven)\ **Post date:** [November 14, 2018, 11:33pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/2 "2018-11-14T23:33:00Z")
Do you live outside the U.S.? I had never heard of filtered milk, so I Googled it and it appears to be a popular item in the U.K. According to what I saw, the iodine is mostly in the milkfat. In the States, the most common source of iodine is iodized salt, or seafood. Deficiency in the first world is extremely rare nowadays, and becoming less and less common in poverty-stricken and mountainous inland areas due to the iodination of table salt, the one food product that everyone on earth uses. ---
**Author:** ![sara20](https://avatars.discourse-cdn.com/v4/letter/s/e79b87/32.png) [@sara20](https://boards.straightdope.com/u/sara20)\ **Post date:** [November 14, 2018, 11:37pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/3 "2018-11-14T23:37:00Z")
> [@nearwildheaven](#): > > Do you live outside the U.S.? I had never heard of filtered milk, so I Googled it and it appears to be a popular item in the U.K. According to what I saw, the iodine is mostly in the milkfat. > > In the States, the most common source of iodine is iodized salt, or seafood. Deficiency in the first world is extremely rare nowadays, and becoming less and less common in poverty-stricken and mountainous inland areas due to the iodination of table salt, the one food product that everyone on earth uses. No I buy it in the US at walmart. This explains a bit about the filtering process [https://fairlife.com/faq/](https://fairlife.com/faq/) I don’t use any salt in my food since I have high blood pressure. I drink only the fairlife skim milk since I am lactose intolerant. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [November 14, 2018, 11:51pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/4 "2018-11-14T23:51:59Z")
The milk I buy is ultrafiltered, but doesn’t say anything about lactose on the label. It does keep a long time refrigerated (3-4 weeks). I can see that filtration could remove bacteria, but not how it could remove a dissolved substance like a sugar (lactose) or iodine. However the casein is somehow denatured (you cannot use it to make cheese and I buy ordinary milk for that). ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [November 15, 2018, 12:10am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/5 "2018-11-15T00:10:52Z")
> [@sara20](#): > > I drink fairlife milk which is “ultra filtered” so the lactose is removed I was going to call woo on this statement, then I read the link. Humpf. Makes some sort of sense. They ultrafilter, or what I would call, treat the milk to a constant flowing dialysis, essential separating everything, then reassembling it into something _like_ milk, with more of some components and less of the ones we associate with bad health. Ho-kay. I’ll play along. Wikipedia doesn’t highlight the amount of iodine in milk in its list of minerals here: [Milk - Wikipedia](https://en.wikipedia.org/wiki/Milk#Salts,_minerals,_and_vitamins) Maybe there aren’t any. Or maybe its negligible. Or maybe no one’s really noticed. As the Fairlife people reassemble the milk, the may add more or less. Maybe they will add it to their FAQ if you ask them. Offhand, their flow filtration ultra dialysis procedure could make more iodine or less. Or have no effect, if the amount there was negligible to begin with. Or a non-consistent effect – i.e. different each time, so not worth talking about. ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [November 15, 2018, 12:23am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/6 "2018-11-15T00:23:45Z")
Also defined more simply here: [Milk - Wikipedia](https://en.wikipedia.org/wiki/Milk#Filtration) one paragraph down. Ultrafiltration essentially strains out water, sugars and likely all minerals except calcium phosphate, which are parts of the Wikipedia article claim stabilizes clumps of casein molecules (I didn’t know that.) Then the Fairlife people add water back, less than they took, so more calcium, phosphorus and casein. It seems likely much of the rest is lost. ---
**Author:** ![Asimovian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asimovian/32/172_2.png) [@Asimovian](https://boards.straightdope.com/u/Asimovian)\ **Post date:** [November 15, 2018, 12:56am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/7 "2018-11-15T00:56:23Z")
**Moderator Note** Thread relocated from IMHO to GQ for the best shot at a factual answer. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [November 15, 2018, 1:10am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/8 "2018-11-15T01:10:15Z")
> [@sara20](#): > > I drink fairlife milk which is “ultra filtered” so the lactose is removed, but milk is the main source of iodine for most people … Not really. Here’s the NIH on sources of iodine: > [@](#): > > ``` > Fish (such as cod and tuna), seaweed, shrimp, and other seafood, which are generally rich in iodine. > Dairy products (such as milk, yogurt, and cheese) and products made from grains (like breads and cereals), which are the major sources of iodine in American diets. > Fruits and vegetables, which contain iodine, although the amount depends on the iodine in the soil where they grew and in any fertilizer that was used. > Iodized salt, which is readily available in the United States and many other countries. Processed foods, however, such as canned soups, almost never contain iodized salt. > > ``` Dairy products as a whole are one of several major sources of iodine. But very few people get all of their dairy just from bottled milk. If someone drinks Fairlife they’ll still be getting iodine from other forms of dairy. I can’t say it would be impossible for a person with a weirdly restricted and unbalanced diet to become deficient in iodine. But such a person wouldn’t get enough iodine even if they drank regular milk. It’s highly unlikely to be an issue for anyone with a varied diet. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [November 15, 2018, 12:22pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/9 "2018-11-15T12:22:51Z")
> **[Ultrafiltered milk](https://en.m.wikipedia.org/wiki/Ultrafiltered_milk)** > > Ultrafiltered milk, also known as UF milk, UF skim, or diafiltered milk, is a subclassification of milk protein concentrate that is produced by passing milk under pressure through a thin, porous membrane to separate the components of milk according to size. Specifically, ultrafiltration allows the smaller lactose, water, mineral, and vitamin molecules to pass through the membrane, while the larger protein and fat molecules (key components for making cheese) are retained and concentrated. (D Ultra... > [@](#): > > Specifically, ultra filtration allows the smaller lactose, water, mineral, and vitamin molecules to pass through the membrane, while the larger protein and fat molecule (key components for making cheese) are retained and concentrated. So everything with a hydrated kinetic radius smaller than lactose is going to be rejected. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [November 15, 2018, 3:10pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/10 "2018-11-15T15:10:03Z")
It was my understanding, perhaps outdated, that people who live near coasts get adequate iodine by eating locally-grown foods. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [November 15, 2018, 3:44pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/11 "2018-11-15T15:44:13Z")
Too much can be as bad as too little, although it seems to be less of a problem for adults who are already fully developed. The people most at risk from low iodine levels are pregnant mothers and their babies. > [@](#): > > The researchers found that the majority of dairy-free milks do not have adequate levels of iodine, with concentration levels found to be around two per cent of that found in cows’ milk > [Dairy-free milks could leave consumers at risk of iodine deficiency, study finds | The Independent | The Independent](https://www.independent.co.uk/life-style/health-and-families/dairy-free-milk-iodine-deficiency-alternatives-almond-coconut-oat-health-study-a7965756.html) > [@](#): > > Iodine is important for the production of thyroid > hormones. It is dangerous to have too little or too > much Iodine. Good dietary sources include fish, > shellfish and dairy products. During pregnancy, > iodine is essential for the correct > development of the baby’s brain. > [https://www.bda.uk.com/foodfacts/Iodine.pdf](https://www.bda.uk.com/foodfacts/Iodine.pdf) ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [November 15, 2018, 11:47pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/12 "2018-11-15T23:47:13Z")
I checked and the milk I buy is called “Pur-filtre” and is not the same as ultrafiltered. It still doesn’t make cheese; I don’t know why. It is not UP milk. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [November 16, 2018, 1:46am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/13 "2018-11-16T01:46:25Z")
Around here, milk _used to be_ a significant (but not necessarily adequate) source of Iodine for people who were Iodine deficient. That was because Iodine solutions were used to treat and help prevent teat infection on the milking cows. That practice stopped because there was some (possibly groundless ??) concern about iodine contamination of the milk ?? In any case, milk is no longer a source of iodine here, and probably not in the USA either. ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [November 16, 2018, 1:52am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/14 "2018-11-16T01:52:59Z")
Actually, Google says the mail provides 35% of the DV of iodine per serving, whereas iodized salt provides 47% per 1/4 tablespoon. So people could well be getting most of their iodine from their milk, if they eat milk often and aren’t salting their food as much. Again, its up to the Fairlife people to explain how much iodine is in their milk after processing. I eat seafood at least once a week usually. I assume I’m getting enough iodine that way. ---
**Author:** ![Grave](https://avatars.discourse-cdn.com/v4/letter/g/71c47a/32.png) [@Grave](https://boards.straightdope.com/u/Grave)\ **Post date:** [November 16, 2018, 2:11pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/15 "2018-11-16T14:11:34Z")
Personal anecdote, apologies in advance. My mother developed a [goiter](https://www.mayoclinic.org/diseases-conditions/goiter/symptoms-causes/syc-20351829) in the early 1990s due to 1) a strict avoidance of salt, 2) rarely eating seafood since fresh water fish is the norm inland, and 3) living on a dairy farm (no commercial dairy products). So even in the US it is quite possible for otherwise healthy people to have an iodine deficiency. The salt avoidance was due to blood pressure issues, and it was probably the biggest contributor. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 16, 2018, 2:13pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/16 "2018-11-16T14:13:03Z")
> [@Arkcon](#): > > Actually, Google says the mail provides 35% of the DV of iodine per serving How much is a serving of mail though? Should I stop recycling my junk mail unread?😉 ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [November 17, 2018, 11:11am UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/17 "2018-11-17T11:11:29Z")
> [@Arkcon](#): > > Actually, Google says the mail provides 35% of the DV of iodine per serving, whereas iodized salt provides 47% per 1/4 tablespoon. So people could well be getting most of their iodine from their milk, if they eat milk often and aren’t salting their food as much. Again, its up to the Fairlife people to explain how much iodine is in their milk after processing. > > I eat seafood at least once a week usually. I assume I’m getting enough iodine that way. Well, around here milk /used to/ provide iodine. Does your google cite provide any information about date and location? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 17, 2018, 2:48pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/18 "2018-11-17T14:48:45Z")
Here’s a pubmed article from 2017 on the topic of iodine levels in milk: > [@](#): > > Milk iodine concentrations in industrialized countries range from 33 to 534 μg/L and are influenced by the iodine intake of dairy cows, goitrogen intake, milk yield, season, teat dipping with iodine-containing disinfectants, type of farming and processing. > **[Iodine in dairy milk: Sources, concentrations and importance to human health...](https://pubmed.ncbi.nlm.nih.gov/29221567/)** > > Milk and dairy products are major iodine sources in industrialized countries. However, consumption of milk and dairy, as well as their iodine concentrations, vary widely, making them an unpredictable iodine source. Milk iodine concentrations in... ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 17, 2018, 3:51pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/19 "2018-11-17T15:51:49Z")
I have nothing constructive to add, although I’m curious to see if there’s an answer. I’m also curious WHY anyone would “ultra filter” milk or drink milk that’s been processed like that. I thought milk treated with lactase to break down the lactose, such as “Lactaid” was the standard work-around for lactose-intolerant dairy-lovers. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [November 17, 2018, 5:43pm UTC](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529/20 "2018-11-17T17:43:44Z")
> [@puzzlegal](#): > > I’m also curious WHY anyone would “ultra filter” milk or drink milk that’s been processed like that. My wife likes that it has 50% more protein and 50% less sugar than regular milk. It’s also lactose free and as mentioned above has a much longer shelf life. [Next page](https://boards.straightdope.com/t/does-filtered-milk-contain-iodine/824529.md?page=2)