The truth about DAIRY

sibetsimo

I have heard so many conflicting opinions on dairy over the years... A teacher in one of my nutrition classes (private school, not university) once said that the tonsils are the glands that produce he enzymes that digest dairy and that they "die" around or before age 6, essentially making everyone lactose intolerant to a certain degree. That's apparently why people sometimes need their tonsils taken out; since they're dead or out of use they are prone to problems and need to be removed.

But then a friend of mine in health sciences at my university said that none of that was true and that we can all digest dairy just fine as adults...

At any rate, I know I'm at least a little lactose intolerant because anything other than skim milk gives me tummy issues and makes me feel sick, and even then I can't have too much skim milk. But it's got quite a bit of protein and no fat and few cals and I do love my cold cereals so I was wondering... is dairy good? Is it good for weight loss? Is there a downside to dairy? Should we really be having several servings a day? Can it be used as a decent protein substitute in snacks without adverse effects?

Sooooo confused!!!!!:noway:

bethrs

Good Question. Wish I had the answer for you.
I guess, the best I've got is that Dairy has been a staple in the American diet, well, a long long time. We don't have a lot of great habits, but considering it's been around soooo long, I wouldn't imagine it could be too terrible for us. it's true that alot of other countries think that america is silly for drinking milk beyond infancy, as some other countries do not consume milk after they are weened from their mothers. But there is more to dairy than milk...

I know that Yogurt is pretty healthy, and I've heard a lot of good things about eating cheese in moderation.

However, just because it's okay for some folks doesn't mean you don't have a dairy allergy or intolerance. Could be bad for you.

krizti_kat

i've done a lot of research on dairy and the thing that strikes me the most about it is we are the only mammals that continue to drink milk after we are infants. and not even milk of our own species! milk is for baby cows. it does not aid in weight loss. it has nutrients in it to grow a tiny calf into a huge animal, think of what it will do to your body. also dairy creates a nasty sludgy layer in your colon (gross i know) which then makes your bowels slower. if your bowels are slow you are not properly digesting your food and getting all the nutrients from it. plus you are probably carrying around a few extra pounds of poo if you go back to when all the "got milk" adds were presented look at who funded them...the dairy farmers. my personal opinion is that dairy is not really good for human consumption, yet we are led to believe it is healthful.

AttilatheHoney8

There is nothing wrong with dairy foods if you are not lactose intolerant. Some hardcore vegans might argue otherwise, but I have yet to see any hard scientific evidence to support that dairy is in any way BAD for those who can handle lactose. However, some forms of milk/dairy are better than others. Obviously if your goal is weight loss drinking lowfat milk is best. I for one, when I can afford it, buy organic milk. Why? Because it negates the issues that a lot of anti-milk people have, such as antibiotics & hormones leeching into the milk and the conditions for cows on organic farms are better as well. I prefer it in taste as well.

Personally, I love milk and nothing I've come across yet in regards to factual and credible evidence has ever proven to me that milk is harmful. I think I would trust your friend in the health sciences when they give you that information as they are learning information that is more recent than what your nutrition teacher from years ago told you .

July24Lioness

I believe that dairy is good for you in its raw, unadulterated form................


I think the pasteurization and homogenization process ruins milk and other dairy, but they do this for supposedly reasons for germs and of course, longer shelf life.

I would rather have, raw, rich, sweet creamy full fat milk, straight from a cow that is going to spoil if it is not consumed rather quickly, than to buy some watery, substance they call 2% or skim milk. Even the regular milk is nothing like raw milk.........


I do eat Fage and Mountain High Yoghurt (it is organic) and I eat raw cheese from my Neighborhood Coop.

I get raw milk from a farmer that lives down the road from me. I also get my chicken and eggs from them also.

jowily

Actually - the tonsils don't produce enzymes to digest milk - the salivary glands start the process, then the stomach (not sure the tonsils actually make anything!) Additionally - the connection between milk tolerance and tonsils is that sometimes milk intolerance causes reactions in the body - including inflaming the tonsil. As such, sometime the tonsil is removed so as not to continue to be inflamed by the bodies reaction to lactose...not the other way around.

courtney_love2001

My physiology teacher recently had a discussion on this...he said that when we are born we have an abundance of enzymes to break down lactose, but as we age those enzymes become much less. That is not to say that we can't enjoy dairy, but it's just saying that we might have a few more problems associated with lactose intolerance.

The way I figure it, there are tons of things that aren't really meant for human consumption, but we do it anyway becaus we enjoy eating those things. What good does insoluble fiber actually do for us? Slow down the digestion process I'm sure, but it all comes out the other end . So IMHO, eat what you wish unless it causes problems...and dairy has done no such harm to me!

I dairy :bigsmile:

and btw...those lactose enzymes are in the GI tract...not the lymphatic system. Tonsils definitely don't do that...unless my professors aren't telling me something!

christahollis

Some things about diary:
The human body produces lactase (the enzyme that digests lactose) in baby/childhood in great quantities--that would be in the digestive system. As we mature, the body produces less--because we're no longer babies who need to be able to digest milk).
Humans are the ONLY species that drinks milk into adulthood...and the ONLY species that drinks the milk of another species. Um...if you actually think about that...yick... The concept of drinking breast milk grosses people out...but seriously...at least it's your own species!
The majority of adults are lactose intolerat to at least a small degree because of the decline in enzyme production.
Milk also has been tested and shown to contain growth hormones, pesticide residues, and other toxins that bioconcentrate just like we see with Mercury and fish. It also contains low doses of opiates--produced by the mother to soothe her calf. AND the milk industry doesn't take ill cows off the line, so if they've got infections in their udders (extremely common)...the pus they produce also goes into the milk...the assumption being that pasturization takes care of any bacteria that come along with it.

That said, it does contain a lot of nutrients along with all the crapola...but...those can all be gained from other sources...so I prefer to avoid it.

Oh... and that whole "organic milk" claim is all but worthless if it's certified organic by the USDA...just in case you didn't know...the farmers associations and processing plants get their own USDA stamp (and can stamp anything they feel like, basically) and are so poorly monitored by the actual USDA that there is no gurarantee that you're getting anything better than regular old milk... with all it's junk.
If you want to be sure it's organic, it should be evaluated by an independent third party.

sibetsimo

I heard that yogurt and cheese were easier to digest because the bacteria in them have sort of already done some of the "digesting", making less work for your own digestive system. I'm hearing a lot of negative opinions on dairy... but what about lactose-free milk? Is there really a significant difference in certain respects other than it being easier to digest for those who have an intolerance?

Thanks for all the replies!!!!!

mrd232

Whole goat's milk is more easily digested by humans for the most part. Yogurt is beneficial on account of the bacteria present, as is kefir.

Personally I just use organic, whole fat milk in moderation.

fjtcjt

ICECREAM, Yum!!! I love dairy products.

SusieSonshine

I have heard so many conflicting opinions on dairy over the years... A teacher in one of my nutrition classes (private school, not university) once said that the tonsils are the glands that produce he enzymes that digest dairy and that they "die" around or before age 6, essentially making everyone lactose intolerant to a certain degree. That's apparently why people sometimes need their tonsils taken out; since they're dead or out of use they are prone to problems and need to be removed.

But then a friend of mine in health sciences at my university said that none of that was true and that we can all digest dairy just fine as adults...

At any rate, I know I'm at least a little lactose intolerant because anything other than skim milk gives me tummy issues and makes me feel sick, and even then I can't have too much skim milk. But it's got quite a bit of protein and no fat and few cals and I do love my cold cereals so I was wondering... is dairy good? Is it good for weight loss? Is there a downside to dairy? Should we really be having several servings a day? Can it be used as a decent protein substitute in snacks without adverse effects?

Sooooo confused!!!!!:noway:

Obviously, it's a controversial subject! However, if you are somewhat intolerant, then I suggest you don't consume it. There are plenty of other alternatives that you can have with your cereal, such as almond milk, soy milk, rice milk, hemp milk, and coconut milk. If you can, get an ELISA test to see what foods might cause an allergic reaction in you. Food intolerances can cause all manner of illness, several of which are Multiple Sclerosis, Fibromyalgia, Candida, etc. The beginnings of these auto-immune diseases, and other allergic reactions can be as mild as lack of energy.

The key is to know your own body and work with it!

All the best to you!

Susie

:flowerforyou:

fjtcjt

Humans are the ONLY species that drinks milk into adulthood...and the ONLY species that drinks the milk of another species. Um...if you actually think about that...yick... The concept of drinking breast milk grosses people out...but seriously...at least it's your own species!

I am sorry but this is a silly statement. Humans are also the only mammals to do tons of stuff. Bears don't cook their meat before eating it so should we start eating meat raw...bears and other mammals will eat their own kind!! Don't compare us to other mammals like that.

If we were like other mammals, anyone with an injury or over weight would be the first to get eaten so everyone would be lean...

July24Lioness

I have heard so many conflicting opinions on dairy over the years... A teacher in one of my nutrition classes (private school, not university) once said that the tonsils are the glands that produce he enzymes that digest dairy and that they "die" around or before age 6, essentially making everyone lactose intolerant to a certain degree. That's apparently why people sometimes need their tonsils taken out; since they're dead or out of use they are prone to problems and need to be removed.

But then a friend of mine in health sciences at my university said that none of that was true and that we can all digest dairy just fine as adults...

At any rate, I know I'm at least a little lactose intolerant because anything other than skim milk gives me tummy issues and makes me feel sick, and even then I can't have too much skim milk. But it's got quite a bit of protein and no fat and few cals and I do love my cold cereals so I was wondering... is dairy good? Is it good for weight loss? Is there a downside to dairy? Should we really be having several servings a day? Can it be used as a decent protein substitute in snacks without adverse effects?

Sooooo confused!!!!!:noway:

Obviously, it's a controversial subject! However, if you are somewhat intolerant, then I suggest you don't consume it. There are plenty of other alternatives that you can have with your cereal, such as almond milk, soy milk, rice milk, hemp milk, and coconut milk. If you can, get an ELISA test to see what foods might cause an allergic reaction in you. Food intolerances can cause all manner of illness, several of which are Multiple Sclerosis, Fibromyalgia, Candida, etc. The beginnings of these auto-immune diseases, and other allergic reactions can be as mild as lack of energy.

The key is to know your own body and work with it!

All the best to you!

Susie

:flowerforyou:

I use hemp milk in my egg creams and protein shakes. It is fabulous!!

SHBoss1673

This is an interesting topic. Some of the stuff I hear about dairy really astounds me.

I'm going to try to throw a little devil's advocate into this because I feel milk's getting a bad wrap here.

1st, we are the only species to drink milk as adults BECAUSE we are the only species with the ability, and tools with which to do so (and actually that's not the case, other species will willingly drink milk if given to them, cats for instance, dogs as well). There's no demonic reason why we do this, it's a relatively humane way to receive a very nutritious and renewable food source (large production dairy farms not widthstanding).

2nd, Pasturization has been studied, tested, and proven to do far more good than the bad it can do. If you live on or near a farm, and can confirm a cow is healthy, and get the milk the same day, then fine, go for it, but that's no guarantee that the milk won't have some parasite in it as well. I'll take my chances with pasturization over getting tuberculosis, diphtheria, salmonella, strep throat, scarlet fever, listeriosis, and typhoid fever among other things.

3rd, of course we have less lactase, we are adults who have the ability and need to use many different food sources, but we are also omnivores who have digestive systems able to deal with all kinds of food and as such we still retain the ability to digest and use a moderate amount of dairy products without issue.

4th, many dairy products contain bacteria that help the digestion process. Beneficial bacteria can help keep us regular and healthy. The idea that milk itself contains hormones and other contaminants is untrue, the milk can carry, if given to the cows that produce it, a small amount of hormones and other toxins, the same way a mother can do so with a breastfeeding infant, that's just ignorance and greed on the part of the commercial farmers, but it has nothing to do with milk itself as a food source. If that's someone's argument, then they have no argument against milk from natural, grass fed cows with no hormones, pesticides, or other toxins in their system. And there are plenty of places around that offer this type of milk.

All that being said, I have no problem with someone choosing not to drink milk for any reason, what I don't understand though, is people using these arguments as ways to shoot down Dairy. Consume dairy, or don't, but I see no reason to tell others to avoid it. That's just MHO though.

fjtcjt

Thanks SHBoss, that is really what I wanted to say...but got distracted with other thoughts and didn't have the time to put it quite as nice as you.

Thanks for being the voice of reason.

paulamma1

Humans are the ONLY species that drinks milk into adulthood...and the ONLY species that drinks the milk of another species. Um...if you actually think about that...yick... The concept of drinking breast milk grosses people out...but seriously...at least it's your own species!

I am sorry but this is a silly statement. Humans are also the only mammals to do tons of stuff. Bears don't cook their meat before eating it so should we start eating meat raw...bears and other mammals will eat their own kind!! Don't compare us to other mammals like that.

If we were like other mammals, anyone with an injury or over weight would be the first to get eaten so everyone would be lean...

Brilliant :laugh:

FireMonkey

Dairy is a great source of calcium. Osteoporosis is no fun and women are at greater risk, especially after menopause - and with life expectancies these days, that can be many years you're living with constant fear of falling and breaking something, and even if you don't break your hip you'll probably get a few compression fractures in your back. They are painful and debilitating.

If you find that you're lactose intolerant, there are ways around it. For most people it's drinking a glass of milk that brings on tummy cramps, but cheese and yogurt is okay. If you really like to drink milk, you can get lactase drops (that's the enzyme) or milk with lactase added. If you can't tolerate any dairy, make sure you get enough calcium in other ways, pill form if necessary.

By the way, the tonsils are part of the lymphatic system - that's why they swell when you get a throat infection. They're fighting off germs!

astridfeline

Humans are the ONLY species that drinks milk into adulthood...and the ONLY species that drinks the milk of another species. Um...if you actually think about that...yick... The concept of drinking breast milk grosses people out...but seriously...at least it's your own species!

I am sorry but this is a silly statement. Humans are also the only mammals to do tons of stuff. Bears don't cook their meat before eating it so should we start eating meat raw...bears and other mammals will eat their own kind!! Don't compare us to other mammals like that.

If we were like other mammals, anyone with an injury or over weight would be the first to get eaten so everyone would be lean...

Thanks, I was going to play devil's advocate with this one---maybe drinking milk is an evolutionary step forward, since cultures that drink more dairy have a higher prevalence of people who produce lactase. :bigsmile:

kankan213

Technically, being lactose-tolerant is abnormal, because the enzyme that breaks down lactase (found in lactose) dissolves at some point before we reach adulthood (I think someone covered this already).

Nonetheless, skim milk, lowfat yogurt and cheeses and things of the like have an abundance of nutritional advantages.

Full fat milk, however, is meant to be drank during times of incredible growth *aka cows double their size in weeks!

I'm not exactly sure why this concept is so controversial. There are a lot of things out there that people should swear off, and I just don't see dairy being one of the hot-topics. Lol, but that's just me.

kankan213

PS- I'm lactose intolerant and I just budget out the dairy that I eat. I have to have yogurt everyday but I make sure to get low-fat and when I drink any milk (usually cooking with it- as I don't drink it) I use lactaid. I steer clear of cheese because I'm not a huge fan and I opt for froyo instead of ice cream. I can't live without yogurt though, and it doesn't upset my stomach.

vanessa915

I've been lactose intolerant since birth, which usually means it's more severe (ie. I can barely tolerate any dairy without digestive consequences). So I didn't really grow up eating dairy products. I didn't drink milk, or eat ice cream (and that sucked as a kid going to birthday parties, let me tell you!), no yogurt, and I picked the cheese off of pizza.

Then they came out with Lactaid when I was in my tween years. I started eating milk on my cereal, having pizza (although I still picked off most of the cheese because I hadn't developed a liking for it), and being able to eat things like ice cream, yogurt, and chocolate. I also gained weight, but I don't necessarily blame the dairy itself, more the fat content of all the new foods I was able to consume. I went in phases of eating dairy and giving it up. I tried lots of different substitutes for it over the years. Eventually I just gave up most of that stuff most of the time, and just ate the real dairy products once in a while, but it wasn't a staple in my diet anymore.

When I was in my early 20's the job I was working at held a health fair that had free bone density scans with the machine that tests it on your heel. My results came back low and they suggested I tell my doctor about it next time I went. So I showed him my results, and he was blown away. He thought it was wrong and said there was no way my results could be that low for my age. But he ordered a full bone density scan for me anyway, just to prove that the other test was wrong and inaccurate. Well, the results came back and I DID have low bone density. He told me to start taking a supplement and to start eating more natural sources of calcium (like low fat milk, yogurt, and cheese), and to do more weight bearing exercises and walking. He wanted to retest me in 2 years, and if I hadn't improved he was going to put me on medication for osteoporosis! I thought only old ladies could get that! (I was only about 24 at the time.)

So I started taking supplements, but I couldn't seems to take them very regularly. But I also upped the amount of dairy I was eating. I ate more cheese and yogurt (lowfat), and started using the lactose free skim milk more often (mostly on cereal since I was never a big fan of drinking milk on its own). 3 years later I had another bone density test and the results came back normal. I was so relieved! So I continue to take supplements (sporadically), and I eat dairy regularly. I buy organic, lactose free milk when I can afford it, but usually I just buy the store brand (and that's still way more expensive than regular milk), and I'll continue to do so because I feel it's helped me be healthier in general. I may not be thin (yet), but at least my bones are in good shape now, and I feel that I have dairy to thank for that.

(Sorry for the long winded response...)

Vanessa

July24Lioness

This is an interesting topic. Some of the stuff I hear about dairy really astounds me.

I'm going to try to throw a little devil's advocate into this because I feel milk's getting a bad wrap here.

1st, we are the only species to drink milk as adults BECAUSE we are the only species with the ability, and tools with which to do so (and actually that's not the case, other species will willingly drink milk if given to them, cats for instance, dogs as well). There's no demonic reason why we do this, it's a relatively humane way to receive a very nutritious and renewable food source (large production dairy farms not widthstanding).

2nd, Pasturization has been studied, tested, and proven to do far more good than the bad it can do. If you live on or near a farm, and can confirm a cow is healthy, and get the milk the same day, then fine, go for it, but that's no guarantee that the milk won't have some parasite in it as well. I'll take my chances with pasturization over getting tuberculosis, diphtheria, salmonella, strep throat, scarlet fever, listeriosis, and typhoid fever among other things.

3rd, of course we have less lactase, we are adults who have the ability and need to use many different food sources, but we are also omnivores who have digestive systems able to deal with all kinds of food and as such we still retain the ability to digest and use a moderate amount of dairy products without issue.

4th, many dairy products contain bacteria that help the digestion process. Beneficial bacteria can help keep us regular and healthy. The idea that milk itself contains hormones and other contaminants is untrue, the milk can carry, if given to the cows that produce it, a small amount of hormones and other toxins, the same way a mother can do so with a breastfeeding infant, that's just ignorance and greed on the part of the commercial farmers, but it has nothing to do with milk itself as a food source. If that's someone's argument, then they have no argument against milk from natural, grass fed cows with no hormones, pesticides, or other toxins in their system. And there are plenty of places around that offer this type of milk.

All that being said, I have no problem with someone choosing not to drink milk for any reason, what I don't understand though, is people using these arguments as ways to shoot down Dairy. Consume dairy, or don't, but I see no reason to tell others to avoid it. That's just MHO though.

I agree with everything you said, except for the pasteurization part.

I find that I lose weight when I consume a lot of dairy (even though it is not my favorite thing, I make myself incorporate it). I lose weight even better consuming raw dairy. Just my opinion and what I grew up on, went away in the army and did not touch dairy for years and years. I have rediscovered it when I moved back to Southern Illinois last year.

jlefton1212

My personal thought on this topic is that food is fuel and building material for our bodies, and dairy products have been proven to assist in strengthening bone development. Granted, it is not the only source of calcium, but it can be great for bone density in addition to green leafy veggies, etc. My mother has osteoporosis at a very early age, due in part to an eating disorder that she had in her late teens and early twenties. She is now trying to make up for the decade or so when she wasn't supplying her body with the appropriate building materials to keep her strong and healthy later into life.

We all have various reasons why we eat what we do, and there are many people on this site that will cut out various food groups (dairy, meat, carbs, etc.). With so many view points, I think the general concensus is that if you remove something from your diet, make sure that you know how it will effect your overall nutrition, and adjust the rest of your diet accordingly. In other words -- if you remove dairy, make it a priority to get your calcium and Vitamin D elsewhere.

almond13

just some food for thought... IMHO I think dairy is an essential part of our diet (esp. in terms of the calcium) however I am lactose intolerent... :grumble: so I did a bit of research on the types of dairy that would be easy on the tummy :laugh: here are some cheesy basics... relative to lactose intolerence :flowerforyou:

Why can lactose-intolerant people eat some kinds of cheese and not others?


It has to do with how long the cheese is aged. Generally speaking, the older the cheese, the less lactose it has. As the chief sugar in milk, lactose is the main food source for the various species of Lactobacillus used in making most kinds of cheese. These bacteria, which are also responsible for sourdough bread, yogurt, kimchee, and dozens of other fermented foods, turn lactose into lactic acid, which is easily digested by humans, even those who are lactose intolerant. The longer a cheese ages, the more of its lactose is consumed by the bacteria. “In theory,” University of Wisconsin-Madison food science professor Scott Rankin says, “most of the lactose is gone after three months of aging.”


Processed cheese has the most lactose. Christine Gerbstadt, a dietitian and a spokeswoman for the American Dietetic Association, points to Velveeta, which has 9.3 percent lactose—as much as whole milk. (Milk is 9 to 14 percent lactose, with skim on the high side and whole on the low side.) Not only is Velveeta unaged, but it also contains added lactose-laden milk solids. Fresh and/or unripened cheese, including Mexican queso fresco, farmer’s cheese, some mozzarella, paneer, cottage cheese, and cream cheese, contains the second-greatest quantities of lactose.

A good rule of thumb: The harder the cheese, the older it is, and the lower the lactose. So the eight-month-old, rock-hard Parmesan will contain less lactose than a softer (younger) Parmesan. Aged cheeses, including Roquefort and some goat cheeses, typically contain around 2 percent lactose.

But there’s no hard-and-fast rule for lactose-intolerant folks to follow—everybody can handle different concentrations. In fact, all people are lactose intolerant to some extent: Eat a whole bunch of pure lactose and you’ll wind up unhappy, no matter who you are. If you have trouble with dairy but still love cheese, Rankin suggests working your way up. Start with small quantities of aged cheeses: a little Parmigiano-Reggiano on your pasta, or some sharp cheddar in an omelet. It is possible to develop a better tolerance for lactose through exposure, so that bowl of Velveeta-and-salsa dip at your Super Bowl party might not be out of reach forever.

almond13

It is possible to develop a better tolerance for lactose through exposure, so that bowl of Velveeta-and-salsa dip at your Super Bowl party might not be out of reach forever.

:laugh: although i don't think i would ever recomend eating a bowl of velveeta. ewe. :laugh: :laugh:

astridfeline

Technically, being lactose-tolerant is abnormal, because the enzyme that breaks down lactase (found in lactose) dissolves at some point before we reach adulthood (I think someone covered this already).

Nonetheless, skim milk, lowfat yogurt and cheeses and things of the like have an abundance of nutritional advantages.

Full fat milk, however, is meant to be drank during times of incredible growth *aka cows double their size in weeks!

I'm not exactly sure why this concept is so controversial. There are a lot of things out there that people should swear off, and I just don't see dairy being one of the hot-topics. Lol, but that's just me.

It's an interesting point about the gene expression for the enzyme decreasing after weaning. However, iit does appear that persistence in cultures that do consume dairy may be an evolutionary phenomenon:

"The lactase enzyme allows lactose digestion in fresh milk. Its activity strongly decreases after the weaning phase in most humans, but persists at a high frequency in Europe and some nomadic populations. Two hypotheses are usually proposed to explain the particular distribution of the lactase persistence phenotype. The gene-culture coevolution hypothesis supposes a nutritional advantage of lactose digestion in pastoral populations. The calcium assimilation hypothesis suggests that carriers of the lactase persistence allele(s) (LCT*P) are favoured in high-latitude regions, where sunshine is insufficient to allow accurate vitamin-D synthesis. In this work, we test the validity of these two hypotheses on a large worldwide dataset of lactase persistence frequencies by using several complementary approaches.

...

Our results show that gene-culture coevolution is a likely hypothesis in Africa as high LCT*P frequencies are preferentially found in pastoral populations. In Europe, we show that population history played an important role in the diffusion of lactase persistence over the continent. Moreover, selection pressure on lactase persistence has been very high in the North-western part of the continent, by contrast to the South-eastern part where genetic drift alone can explain the observed frequencies. This selection pressure increasing with latitude is highly compatible with the calcium assimilation hypothesis while the gene-culture coevolution hypothesis cannot be ruled out if a positively selected lactase gene was carried at the front of the expansion wave during the Neolithic transition in Europe.



The "calcium hypothesis" idea is of course one of the explanations for light skin in Northern Europe as well. The locus responsible for 1/3 of the skin color difference between Africans and Europeans, SLC24A5, is a relative recent sweep, on the order of the last 10,000 years. The authors do caution to be careful about the assumptions of their model. Point taken to heart, as I don't think they have a good enough grasp on the fine-grained variation in the lactase persistence alleles and how they track ecology within Europe. The Greenland Norse did not raise cattle just because of lack of Vitamin D (which they ended up getting through a shift toward a marine diet in any case), rather, there were ecological constraints in terms of the maximum productivity of grain-based subsistence farming (particularly with wheat in cold damp climates). In the conclusion of the paper it is noted that Iberia is a good test case of the model, and more data needs to be gathered there. If it is gene-culture coevolution than many Iberian peoples should be lactase persistent, but if it is due to Vitamin D, they should not be. "

taken from http://www.gnxp.com/blog/2009/07/lactase-persistence-pastoralism-in.php

I only have time to look this one source up, but it's such an interesting topic I will look into it more later to get a wider perspective.