26 May 2010

Calcium and protein: friends or foes?

In the last post, we saw that dairy products are a fine source of calcium, thanks to the absorption-enhancing property of lactose and the density of calcium by weight or calorie. So why consider anything else? I think many people have an idea that protein, in which dairy products are rich, interferes with calcium or bone health in some way. In the chapter on bone health in Krause’s Food and Nutrition Therapy, John JB Anderson states that “the relationship between protein and calcium is unsettled” (625).

Let’s take a step back. What is this relationship? On the one hand, protein is considered to have an anabolic (building) effect on bone. After all, around 25% of the bone matrix is protein in the form of collagen fibers. Calcium and phosphorus make up the hydroxyapatite that gives bone its rigidity. On the other hand, a chronically low intake of protein decreases the serum concentration of albumin, a protein that transports nearly everything in the blood, including calcium (Anderson, 625).

So why would high protein intake pose a problem? Here’s where the textbook gets a little fuzzy. First it says that “actions of proteins and their absorbed amino acids… [have] a catabolic [breaking down] effect resulting from the generation of an acid load” (625). But as far as I can tell, extracellular excesses of acid are buffered primarily by bicarbonate - calcium doesn’t have much to do with it.

The second reason given is that urinary losses of calcium increase following meals that contain large amounts of animal protein (625). The exact mechanism is not clear, but it may be because the sulfates generated by the metabolism of sulfur-containing amino acids (cysteine, cystine, methionine) bind to calcium ions in the kidney and prevent them from being reabsorbed (Gallagher, 115). A list of food sources of sulfur follows: meat, poultry, fish, eggs, dried beans, broccoli, and cauliflower. This is a bit misleading, as 3 oz of beef has fourteen times as much methionine as 1 cup of cooked broccoli.

Studies tracking protein consumption and bone fractures or bone mineral density are… numerous. Some come out in favor, some come out a wash. I would say that most people should consider getting more calcium from vegetables, and in the next post, I’ll explain why it’s a great idea.

Photo source: fooducate.com

24 May 2010

Can we use calcium from dairy products?

A few weeks ago when I entered Aunt Gayle’s hospice room, the gathered family had a nutrition question for me: can humans absorb the calcium found in milk and other dairy products? I was fairly confident that dairy is a good source of calcium and is well absorbed. If not, the government and the dairy industry’s been doing us a huge disservice for decades.

Then my mother-in-law raised the same question this weekend. Her doctor had recommended leafy greens as a calcium source. Again, I was fairly confident that most leafy greens are a good source of calcium, though not necessarily as well absorbed.

So what's the deal? Should one consume dairy products for the calcium? My newly purchased textbook, Krause’s Food and Nutrition Therapy, by L. Kathleen Mahan and Sylvia Escott-Stump (Saunders-Elsevier, 2008), offers two reasons to do so. First, dairy products are the most concentrated calcium sources, and second, lactose enhances calcium absorption, probably even in those with lactose intolerance (104, 106).

A cursory glance at a Google Scholar search related to lactose-enhanced calcium absorption reassured me that this reason was probably valid.And while "most concentrated" sounded about right, I was curious as to how exactly that played out.

I started calculating the concentration of calcium in some foods, both dairy and non-dairy to get some numbers. I began by calculating milligrams of calcium per calorie, but that didn’t result in dairy being uniformly more concentrated:

Food

Calcium (mg)

Kcals

Mg Ca per kcal

Yogurt, plain, low fat, 1 cup (245g)

448

154

2.9

Milk, 2%, 1 cup (144g)

286

122

2.3

Cheddar cheese, 1 oz (28g)

202

113

1.8

¼ block firm tofu (81g)

163

57

2.9

Kale, 1 cup cooked (130g)

94

36

2.6

Broccoli, 1 cup cooked (156g)

62

54

1.2

Almonds, 1 oz (28g)

75

169

0.4


Tofu stands eye-to-eye with yogurt, a cup of kale beats a cup of milk - what's going on? I switched to milligrams of calcium per gram, which still didn’t yield the results I expected:

Food

Mg Ca per gram

Cheddar cheese, 1 oz

7.2

Yogurt, plain, low fat, 8 oz

1.8

Milk, 2%, 1 cup

1.2

Almonds, 1 oz

2.7

¼ block firm tofu

2.0

Kale, 1 cup cooked

0.7

Broccoli, 1 cup cooked

0.4


Here, water content plays a big role - generally the more water, the heavier the food is. Cheddar is the leader by far, since cheese is basically milk wrung of water. This time, almonds are doing pretty well, and tofu is still a champ. NOTE: These calculations are based on calcium-set tofu, not the silken type, which has about 80% less calcium. Straight-up cooked soybeans have about 0.6 mg Ca per kcal, and 1.0 mg per gram.

Bottom line – the author of the statement "Cow's milk is and dairy products are the most concentrated sources of calcium" has a different understanding of “concentrated sources” than I do.

Next up: the relationship between protein and calcium.

Photo Source: UMN Extension

21 May 2010

Childhood (Mis)conceptions

Every morning this week, I've showed up at the U of M's student organic farm. I stick around for a couple of hours, helping out with the tasks at hand: transplanting pansies, harvesting chives and cilantro, weighing the produce, thinning the turnips.

My mind often turns to images formed of farming in my childhood by the Little House on the Prairie books and even The Boxcar Children. Of course, we've got a Prius and more water sources than you can shake a stick at, but I hoof it an awful lot and watering, although it doesn't involve lugging water buckets, can still be tedious.

And then there's thinning plants. You may recall that in the first Boxcar Children novel, back when they were actually living in a boxcar, the Alden children do yard work for Mr. Henry. One task was to thin the carrots. I really had no idea what this meant: I imagined Jessie pulling out a carrot, running it between her fingers to "thin" it, and putting it back in the ground. Why would anyone pull out perfectly good carrots? When Jessie asks to take home the pile of thinned carrots (apparently they didn't all make it back into the ground), I always imagined a heap of pale, pinched roots, ready to wilt at a second glance.

The reality is less laborious. Thinning involves only the removal of the smaller plants, no size-reduction at all. We ended up with a healthy pile of turnip greens that destined for the Campus Club. No humble junkyard stew pot for these organic roots.

Photo source: http://mysticdomestica.blogspot.com/2009/07/boxcar-kid.html

17 May 2010

Program reciprocity

This essay for a scholarship for HECUA's Environment and Agriculture program answers the question of what I thought I could contribute to and receive from the program, and how my participation would benefits myself and others. Bottom line: I want my kids to know that Brussels sprouts are a fall vegetable and delicious with mustard.

Environment, Agriculture, and Brussels sprouts

My mother grew up with a kitchen garden in the backyard and canned vegetables in the basement. I grew up helping her shop at the co-op and shucking corn from the farmers’ market. So it surprised both of us when one summer afternoon in my teenage years, I could not say if Brussels sprouts were in season. My mother had assumed that I had a clear conception of seasonality, but all I really knew was that citrus fruits were somehow “in season” in the winter. Not long after this, I launched in the study of nutrition, working my way from Introductory Chemistry to Physiology to Medical Nutrition Therapy. Missing from my classes, however, has been a comprehensive look at how healthy food, the foundation of nutrition, gets to our plates. This Environment and Agriculture program promises to flesh out my understanding, cobbled together through reading books and articles on my own, so that I can more effectively work toward just and sustainable food systems in Minnesota.

To this program, I can contribute thoughtful discussion and openness to new ideas. Before attending the University of Minnesota, I spent two years at Lawrence University, a liberal arts college in Wisconsin. Small class sizes and a tight-knit community fostered thoughtful discussion. There, I learned how to prepare well for class and lead discussions. Later, after a semester abroad, I became more open to new ideas that challenged my previously held beliefs. I came to realize that no idea, no matter how great it sounds, comes without drawbacks and should be weighed carefully. As much as I want to see issues in black and white – organic good, pesticides bad – I realize that life is painted in shades of gray.

Environment and Agriculture will surely give as well as receive. I believe I will gain much from this program, both personally and academically. I do want to know where my food comes from and how to grow it, but often these tasks seem overwhelming. I’m not prepared to interrogate each farmer at the farmers’ market or figure out how much light my backyard gets or what the soil pH is. I believe this program will help me take strides forward in this arena, giving me the vocabulary and confidence to talk with farmers and, through an internship, getting my hands in some dirt. These strides will help me achieve my goal to become a registered dietitian who considers the impact a diet will make not just on the health of her client, but also on the health of the soil it came from and the people who harvested it. Academically, I look forward to breaking away from lectures and professors, and learning from my peers and food system actors.

The benefits of this program will not be confined to my own personal and academic goals. I anticipate great benefits for the issues that I care about – school lunch, food deserts, and animal cruelty. I look forward to meeting and building relationships with local farmers because I want to be an able implementer of farm-to-school programs around the state. With a deeper understanding of food system politics and economics, I could contribute to or evaluate plans for eliminating food deserts in urban and rural neighborhoods. I need to see farmers treat their livestock with compassion to balance out the images of animal cruelty I’ve seen over the years. I plan to use everything I learn on this program to help me be a more better advocate for sustainable food systems.

There are others who will benefit from my experience in with Environment and Agriculture – my future children. I want to be happy to have them eat school lunch. I want them to always be within walking distance of a grocery store. I want them to know that drumsticks come from a bird that has feathers and a personality. I want them to know the work that farmers do and appreciate truly healthy food is. And, I want them to know they have to wait until fall for Brussels sprouts.

10 May 2010

Food Not Bombs and Me

March was essay-writing time as I applied for scholarships and the HECUA summer program. I wrote an essay for the iModules scholarship about how my time with Food Not Bombs affected myself and the group. Unfortunately, I was not one of the eight lucky recipients. Tune in next week for an essay that did pay off.

The Power of Meals: Food Not Bombs and Reciprocal Impacts

“Class projects don’t have to be dull,” I reassured myself. “I can make it something I’m interested in.” The assignment was to volunteer with an organization, any organization, and write about it. A classmate invited me to cook with her at the Food Not Bombs (FNB) house in Minneapolis. Cooking a free meal for the community from food that had been gleaned or rescued from a dumpster sounded much more interesting than sorting canned goods at a food shelf. Indeed, after one afternoon with FNB at their house, I was hooked, and returned week after week. Making meals with FNB had a profound impact on my understanding of waste in the food system, my perspective on dinnertime, and how an individual can make a difference.

That fall of 2008, my understanding of how our food is distributed and wasted was limited. Stepping into the FNB kitchen showed me the enormous amounts of food waste associated with grocery stores alone. A garbage bag brimming with bun, rolls, and loaves of all varieties would be sitting in the corner, waiting to be made into bread pudding. Three or four boxes of produce would be stacked in the middle of the floor. After sorting out the few items into the compost that were spoiled, the sweetly ripe and fragrant remainders were chopped into a fruit salad. Talking to those who had picked up the culled produce from the co-op or plucked the baked goods out of a grocery store’s dumpster was eye-opening. This tasty, edible food was either not pretty enough, past its expiration date, or pulled simply to make room for a new shipment. It went straight to the dumpster because that was easier, legally and logistically, than donating it to food shelves. I had not realized the extent to which grocery stores were willing to waste food in order to keep their shelves brimming with food, and unwilling to feed the hungry with the excess.

Transforming the urban harvest into a meal for the hungry was only half of FNB; building community was the other. That winter, FNB had not been able to find an indoor alternative to the local park where they normally served, so they invited people to dine in their living room. Spending the evening enjoying each other’s company without the aid of electronics, was an embarrassingly foreign experience to me. Caleb, organizer of most meals, played the guitar and regaled us with stories about tapping maple trees in a blizzard. We made up knock-knock jokes with Gabe, a bright six year-old. We took turns struggling with a marble tilt maze. In short, FNB meals were much more than fruit salad and bread pudding. The whole evening, we shared our talents and experiences with food or music or jokes. Furthermore, we strengthened the ties between the diverse people that shared FNB meals. To me, this is a model for mealtimes – they should be about more than just eating, and be a time to enjoy and appreciate each others’ talents over good food.

I relied on FNB for food and friendship through the winter, but my attendance became spotty the next semester. When I arrived one spring day ready to cook, I was stunned by what I saw. Unfamiliar people were picking over the contents of the house that were spread all over the porch and front lawn. I spotted Caleb in the back yard. “What’s going on?” I asked. “We got evicted,” he replied. I was stunned. Where would the residents go? Where would they cook? “Are you going to serve tonight?” I asked. Caleb distractedly listed some of the elements that had to come together: someone needed to pick up produce from the co-op, makeshift wood-burning stoves needed to be transported to the park so that we could cook there, and there were some mung beans left in the kitchen to prepare. I could not bear to abandon Caleb, so I headed to the disarrayed kitchen to tackle the beans. Caleb made some calls and found someone to pick up the produce. Together we packed dishes, utensils, stoves, and all the food I could scrounge up onto bike trailers. We hauled it to the park, where a small crowd was waiting for us. The produce arrived from the co-op and everyone rummaged through the boxes of berries, plums, and lettuce while I set up the food and Caleb lit the stoves. More people arrived. I greeted some familiar faces and some visitors from out of town. Finally, incredibly, the meal was in full swing. Despite the confusion and disorder of the afternoon, we had managed to distribute good food and build community, as scheduled. “You helped make a miracle here today,” Caleb smiled a twinkle in his eye.

This experience more than any other showed me the power of one person to make an impact on a community. I had set out to have fun assisting in a routine activity, but when I saw the house and its residents in disorder, I could not just walk away. I realized that my ties were deeper and that I could take on the more serious work of preparing a meal. Because I supported Caleb through preparing and serving a meal in the midst of an eviction, a few dozen people got healthy food and caught up with friends that night. This sense of empowerment compounds the other impacts FNB made on me: in the face of meals on the run, as one person, I can invite a group to spend the evening making dinner and entertaining ourselves. In the face of excessive waste, I can ask my managers at work about reducing waste or composting. The lessons from one class assignment that was decidedly not dull expanded my conception of nutrition to include the health of both the food system and my community.

03 May 2010

Purple Asparagus

My mission this summer is to get my hands in some land and grow some food. Today I took one small step toward that goal.

One of the options I considered for the internship component of the HECUA summer program was working on the U of M's student organic farm, Cornercopia. The program coordinator, Courtney Tchida, invited me to help out during class time.

I trekked toward the far northwest corner of the St. Paul Campus until I spotted a group of people hoeing and wrestling with hay. Courtney put me to work right away: I planted Brussels' sprouts and cauliflower, and mulched. Then she asked for volunteers to harvest asparagus and spinach. I was by her side in a flash.

The asparagus was planted in a large V and I had to look carefully for the clumps of purple shoots growing among the other vegetation. I snapped off likely looking stalks of all heights and thicknesses - stalks as thick as a quarter and as tall as my palm, stalks as thin as a pencil and almost up to my knee.

Each was astonishingly juicy and the ends that I popped into my mouth were as tender as anything. It hardly seemed like the same vegetable as what I'd get at the store. I felt like I was in the garden in Narnia, where all the fruit tastes infinitely better than the best you'd ever tasted. Everything I picked was destined for the Campus Club. Lucky ducks.

Photo source: http://www.jungleseeds.com/SeedShop/StemFruit.htm