Wednesday, November 4, 2009

I'm deficient, You're deficient, We're all deficient? (Part 2)

In yesterday's Part 1 about nutrient deficiencies in the gluten-free population, I posed four critiques and questions that I promised to answer in today's part 2. Without further ado, here we go...

Critique #1 questioned the small sample size of the research. I can't do anything about that, and there's not much to be said about it, so let's move on.

Next, I think it's easiest to address critique #3: How did nutrient deficiencies in the GF population compare to Americans as a whole? To answer that question, I pulled data regarding nationwide averages from the USDA's Community Nutrition Mapping Project. If I amend yesterday's table that showed the percent of the GF population who are deficient in given nutrients, and add to it a column for the national averages, this is what you find:


NutrientGF DeficiencyNationwide Deficiency
fiber74%92%
calcium82%69%
thiamin59%19%
riboflavin25%11%
B635%26%
folate85%40%
B1229%20%
iron41%11%

These numbers change the perspective a bit, I think. It's not simply that the GF population is nutrient deficient. When you compare us to the national averages, it gets slightly more complex. In some cases, such as folate, riboflavin, thiamin, and iron, we're two or more times as deficient (as a group) than the nation. However, in other cases, such as B12, B6, and calcium, we still have greater rates of deficiencies, but we're also in the same ballpark as the national averages. And in one case - fiber - we're actually LESS deficient than the national average. Interesting.

Which brings me to critiques #2 and #4: are there differentiations within the GF community (processed GF foods, whole grains, fresh fruits and veggies and meat and fish), and is the GF diet to blame or are other factors (i.e. nutrient malabsorption) to blame?

First, it's important to note that if you're an undiagnosed Celiac, or if you're a newly diagnosed Celiac whose villi haven't had a chance to heal in the small intestine, then nutrient malabsorption is undoubtedly a factor to consider. Even those who have been on a gluten-free diet for prolonged periods of time may have persistent nutrient malabsorption problems, especially with fats, certain vitamins, and calcium (whose absorption rate is impacted by the vitamins).

Second, it's also important to note that for many Celiacs (as well as for some with gluten intolerance), the gluten restriction is also coincident with lactose intolerance, casein intolerance, or both. This leads to a natural shift away from dairy products such as milk, cheese and yogurt, all which can be good sources of calcium. Unless you diet is rich in non-dairy sources of calcium, and unless you take a multivitamin supplement, it wouldn't be surprising to find that you're calcium deficient. (And as you may know, bone density loss and osteoporosis are both secondary health concerns for those with Celiac.)

That's as much as I'll say about contributing factors other than the GF diet itself. As for the GF diet, this is where the rubber really meets the road, as they say. I was curious whether the GF diet was indeed nutrient deficient when compared to a "standard" gluten diet. The primary distinction between gluten and gluten-free diets is of course the gluten. And so that's where I focused my attention - by comparing a baseline wheat flour (all-purpose enriched unbleached wheat flour [W]) with a range of gluten-free substitutes (cornstarch [C], brown rice flour [BRF], potato flour [PF], tapioca/cassava [T/C], arrowroot flour [AF], sorghum [S], cooked quinoa [Q], cooked amaranth grain [AG] and cooked millet [M] ). Once again, I pulled my data from the USDA's National Nutrient Database. (A couple words of note. In the following table, I've rounded decimals for space. Also, the USDA database does not include sorghum flour, so I've used plain sorghum. Ditto for the quinoa. Tapioca starch isn't listed either, so I've included both raw cassava and tapioca pearls. In all cases, the values are for one cup of the given food. Because I couldn't compare equivalent starches/flours across the board, it's not a perfect comparison, but it gives a very good general sense of things...)


NutrientWCBRFPFT/CAFSQAGM
fiber3.41.27.39.41.4/3.74.412.15.25.22.3
calcium1931710430/335154311165
thiamin0.9800.70.370.01/0.1800.460.20.040.18
riboflavin0.6200.130.080/0.100.270.20.050.14
B60.0601.161.230.01/0.180.0100.230.280.19
folate229025406/5690785433
B1200000/000000
iron5.80.63.132.212.4/0.560.428.452.765.171.10

Whew. That's a lot of numbers. What does it all mean? Well, first take a look at the first row, which lists the values for fiber. Remember how fiber was the one nutritional component measured in the study where the GF population was less deficient than the national average? Suddenly that doesn't seem too surprising. With only a few exceptions, the broad suite of gluten-free grains contain more fiber than the wheat baseline.

Secondly, take a look at the second row, which lists the values for calcium. Again, with only a few rare exceptions, the broad suite of gluten-free grains contain higher levels of calcium than the wheat baseline. Now hold on a minute. The GF population is more calcium deficient than the national average, not less. What gives? The data here tell me that the calcium deficiency is not due to the gluten-free diet. I'd be willing to wager that our higher prevalence of calcium deficiency is due to two factors: an avoidance of dairy products due to lactose/casein intolerance, and calcium malabsorption. Never the less, it's not the fault of the gluten-free diet.

Thirdly, take a look at the rows for B6 and B12. You'll immediately see that B12 has zeroes across the board. That's because B12 isn't available via plants. It comes primarily from meat, poultry, dairy, etc. Then there's B6. As you can see, wheat is pretty poor source of it. The ancient grains - quinoa, amaranth, and millet - are comparatively much better. But best of all are the brown rice flour and potato flour. It just so happens that brown rice and potatoes are decent sources of B vitamins. So again, the gluten-free diet itself doesn't seem to be to blame here.

Lastly for my analysis, I think it's very useful to recall my differentiation beteween various types of GF diets. First, there's the GF analog of the standard American diet, comprised primarily of heavily processed foods. The GF components of those foods are typically corn, rice, tapioca, and to a lesser degree, potato. You'll find those all in columns 2-5. As you can see, cornstarch and tapioca especially are poor sources of nutrition. They offer very little. Is it any surprise, then, that a diet heavily dependent upon these starches would be nutrient deficient? Brown rice flour and potato flour aren't as bad. They're actually pretty decent in their nutrition (especially when compared to cornstarch and tapioca!)?

Then, what if we consider my second grouping, which includes a GF diet that incorporates more whole grains and the "ancient" alternative grains (sorghum, quinoa, millet, amaranth)? Then the nutritional picture starts to look even better. As a group they're more nutrient dense than the first group. Plus, many of the ancient grains offer the complete set of amino acids. That's a big added bonus.

The most striking to me, though, is that the gluten-free alternatives to wheat aren't necessarily all that different from the wheat flour baseline. In some cases, they're actually preferred from a nutrition standpoint.

But even more important to recognize is that none of these grains - from wheat right down to the ancient grains - are great sources of the nutrients which the research study focused on. You shouldn't be making these starches - whether you eat gluten or not - as the basis of your nutrition. Sure, they can be a good source of carbs. But when it comes to rounding out the nutrient intake, look elsewhere.

And that brings me to the third of my three groupings: the GF set who eat a high percentage of fresh fruits and vegetables, as well as whole meats, fish, etc. They're going to be the best off nutritionally. If you look at the government's Dietary Guidelines for Americans, you'll find that the best dietary sources of various nutrients have nothing to do with wheat or cornstarch or, for the most part, any of the other grains I profiled. Here's a sampling of the best dietary sources of different nutrients:

iron - soy, beef, beans, lentils, spinach, chickpeas, tomato, some seafood

calcium - tofu, salmon, molasses, spinach, soy, beans, kale, yogurt, milk, cheese

fiber - beans, peas, lentils, soy, fruits and vegetables (including banana, orange), sweet potato, whole grains, nuts and seeds

B6/B12 - meat, chicken, eggs, asparagus, broccoli, spinach, bananas, potatoes, milk, cheese, nuts, fish, brown rice

You know what I notice? That entire list is naturally gluten-free. The million dollar take home message is thus: if more gluten-free people ate a diet well-rounded with whole GF grains, including the ancient grains, and rooted that diet in fresh fruits and vegetables, and whole meats and fish, it would go a very long way toward battling nutrient deficiency in the GF diet. Keep that in mind the next time you're at the grocery store, or planning a meal.

13 comments:

Jen said...

Thanks for taking the time to research yesterday and today's articles. I found them very helpful and informative- and it's nice to know that it is possible to get the nutrients we need while avoiding wheat. Thanks again!

peterbronski said...

Hi Jen... Very glad you found the posts informative and helpful! When I start hearing about things like nutrient deficiency, it gets my attention since it's a potentially serious topic (and one where I can put my journalism skills to use). I couldn't help digging deeper to find substantive answers to important questions. Happily, the answers to those questions led me back to what I've said about diet for a long time, and one that is a fundamental theme in our cookbook - that eating fresh, whole foods, like fruits, veggies, meats, fish, whole grains...is the best way to go. It's certainly not earth shattering news, but it helps to be reminded every now and then. =)

Cheers, Pete

Erin said...

Peter,
Awesome posts. Thanks for covering this. I will be linking back to this from my blog-and it once again reinforces that naturally gluten free foods are a great way to go!

Cheryl Doyle-Ruffing said...

Pete,

Great posts; great analysis. If you'd like to turn your talent to a slightly different topic, soy may be the one. It's a gluten-free grain with a mixed reputation. I'd love for you to sort through it all.

peterbronski said...

Hi Erin... Glad you enjoyed the two-part series. Thanks for linking to it! Yes, so often it call comes back to the naturally gluten-free foods, and whole, fresh foods. It's a good rule of thumb to follow no matter what diet you're on - gluten, gluten-free, vegetarian, etc.

Hi Cheryl... Thanks for your comment! Also glad you enjoyed the info and analysis. I love your suggestion to tackle soy. It's on my radar screen for sure. I'm hoping to be able to get to it in the next few weeks. Stay tuned! That's going to be a good one...so much info to sort through on both sides of the issue!

Cheers, Pete

Elizabeth said...

Fantastic post! It was interesting to see the GF and non GF diet deficiencies compared with each other. And you made some great points that processed gluten-free foods, are really not really any healthier than regular processed foods. Not only are they many times higher in calories, but also lack nutritional benefits. I think this is a great post for those who are gluten-free and those who are not. The more fresh veggies, meats, fruits..etc no matter what type of diet, the better.

gfe--gluten free easily said...

Pete--I really appreciate it when you do these types of articles. I know how much work must go into them. A couple of points though ... If you look further, you'll find that dairy is really not the best source of calcium for the amount of calcium provided and calcium that's best absorbed. Here are just two links that share that type of info. The Dairy Council would like us to think otherwise, but there are people who don't eat dairy who have great calcium levels, great bones, etc. My bone density went up greatly during my year after going gluten free when I was not eating dairy, but walking daily, taking a high quality bone guard supplement (much more than calcium), eating lots of leafy greens, nuts, and other calcium-rich foods, etc.

http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/calcium-full-story/index.html

http://bastyrcenter.org/content/view/167/&page=

A couple of other calcium notes. A recent study showed that bone density issues in celiac are related to inflammation as much or more than the malabsorption issues. I had just read about these findings, but then Dr. Stephen Wangen brought them up when he spoke at a support group meeting I attended last week.

The fact that we are not as fiber deficient probably has a lot to do with all those fiber "prescriptions" we've received over the years to solve our, uh, other issues. I, for one, was on Fibercom and the like for literally years. Fiber is prescribed for both extremes of GI issues caused by gluten intolerance.

Of course, I love your last bit of info. Real food ... naturally gluten free! :-)

Thanks, Pete!

Shirley

peterbronski said...

Hi Elizabeth... Thanks for chiming in! Yes, the fresh fruits and veggies, whole meats, etc. is definitely the way to go!

Cheers, Pete

peterbronski said...

Hi Shirley... Thanks for adding your insights. However, I do have to clarify a few points as well as disagree with you in places:

Dairy IS a good source of absorbable calcium. I'll quote directly from the sources (Harvard) you provided - "Good sources include dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark leafy greens or dried beans, which have varying amounts of absorbable calcium."

Of course, dairy isn't the only source of calcium, and in my list of dietary sources, I include a wide array of non-dairy options which can be and are valuable sources for people who don't consume dairy.

It's also true that exercise (especially weight-bearing) is important for bone density. However, that's not a nutritional deficiency issue.

Similarly, the information on bone density and inflammation - while certainly pertinent - does not directly relate to nutrient deficiency in the diet. Inflammation's contribution to bone density loss is a separate issue. In addition, numerous studies (including recent studies published last month) have shown a full restoration of bone density once a Celiac is on a gluten-free diet. Dr. Wangen discusses a new Scottish study in which bone density is impacted by an autoimmune response in a small fraction of Celiac patients. But again, that's not a diet nutrient deficiency issue.

Calcium malabsorption, on the other hand, relates directly to nutrient deficiency. If dietary intake is already calcium deficient, and you then have malabsorption issues, it compounds the deficiency.

Finally, on the fiber point, I don't think you can make the argument that fiber supplements are the cause. Remember that the subjects of the study had been on a GF diet for at least 5 years. Presumably, they would no longer be on fiber supplements aimed at addressing other or undiagnosed GI issues. Their heightened fiber intake is purely a function of diet.

Cheers, Pete

gfe--gluten free easily said...

Pete--I did mix apples and oranges here and I apologize for that. I think the Harvard article really questions whether dairy products are best for us, given other factors. It also mentions the fact that there do not seem to be huge bone density issues in other countries that do not consume dairy (or much dairy). Again, that seems like mixing apples and oranges, but sometimes it's hard to separate "issues." I love the taste of dairy, but I don't believe we need it and I don't think we necessarily benefit from it--what I've read indicates that often it's quite the opposite. But, I don't want to enter into a big discussion. We can all read on our own and make our own decisions.

Re: fiber, I'm sure you are correct that a better diet when eating gluten free plays into the fiber numbers. I know I eat far more fiber than I did even when I was on my fiber supplement plan (ugh), and, of course, am much healthier for that. I suspect the folks who are still eating highly processed foods who are still taking the fiber supplements. But, you're probably correct that after that period of time of eating gluten free, the numbers aren't attributable to anything other than diet. It would certainly be nice to see the value of the numbers matched to the specific gluten-free diets ... highly processed to largely fruits and vegetables.

Anyway, great discussion. I'll look forward to your thought-provoking posts (as much as the mouth-watering recipe posts) always! :-)

Shirley

peterbronski said...

Hi Shirley... Didn't mean to put you on the defensive when it comes to calcium. There are certainly many other related issues to consider, like the relative merits of dairy vs non-dairy sources of calcium, the claims of the dairy industry lobby, and more. I think the most important thing for people (i.e. readers of our blogs) to remember is that in the gluten-free diet, there are a wide variety of good options - both dairy and non-dairy - for dietary sources of calcium. The dietary calcium deficiency identified in the study then, isn't necessarily a result of the GF diet itself. Rather, it's other related factors that are resulting in it.

Maybe I'll have to work on a post series about bone density issues in celiac and gluten intolerant folks, which would give me a chance to appropriately address some of the other issues you've so rightly talked about!

Cheers, Pete

Mindaugas said...

Thanks for the info!

peterbronski said...

Hi Mindaugus... No problem!

Cheers, Pete