The authors’ Rebuttal
...to the Dairy Farmers of Canada Response
to Becoming Vegetarian
1996

Parts: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8
(Part 5)

Page 24

1. "Where did the authors of the book find this myth? We are unaware of anyone ever having said that it's virtually impossible to get enough calcium without dairy products; it is just a lot harder in our culture." [referring to our myth: "It is virtually impossible for your diet to meet your calcium needs without milk and milk products."]

Recall that a myth is a collective opinion, belief or ideal that is based on false premises.1 A myth is seldom based on a single statement of fact, but rather on a variety of materials and experiences which have been exaggerated or misinterpreted. The myth to which we referred in Becoming Vegetarian is one that is very prevalent in our society. Where did this myth come from, our critics ask? Well, perhaps the first place they could look is their own advertising.

Aug. '96, It's Your Health, Reader's Digest, Controversies, Myths and Udder Nonsense.

Here is one of the "myths" discussed in this advertisement: "Forget milk products, we can get calcium from other foods".

Might that "myth" make people think it is impossible to meet calcium needs without milk? Here's what is said about this "myth":

" Of course there's calcium in other foods besides milk products. But can we meet our daily calcium needs eating them? With great difficulty...To get the same 300 mg of bioavailable calcium, you'd have to eat either 11 cups of kidney beans, 8 cups of cooked spinach, 2 1/2 cups of sesame seeds, 2 large servings of calcium-processed tofu or 2 1/2 cups of broccoli."

Statements made in this advertisement are not only misleading, they are downright false. Their big mistake was claiming that 1 cup of milk contains 300 mg of bioavailable calcium. In fact, as they well know, a cup of milk provides approximately 96 mg of bioavailable calcium. (32% of the calcium present in milk is bioavailable --not 100% ). Then they compare the amount of various plant foods required to provide a similar amount of bioavailable calcium. Our calculations resulted in somewhat different answers:

· kidney beans -- red, California 3.8 cups (based on an absorption of 21.9%)

· red, royal 5.6 cups (based on a 21.9% absorption)

· sesame seeds -- whole 1/3 cup

· hulled 2.8 cups

· tofu (made with calcium) -- firm - 1.2 (1/2 cup servings)

· medium - 2.4 (1/2 cup servings)

· broccoli, cooked -- 2 x 1/2 cup servings (based on an absorption of 52%)1,2

1. Pennington, J.A. Bowes and Church's Food Values of Portions Commonly Used. 16th Ed. Philadelphia: Lippincott Company, 1993.

2. Weaver, C.M., Heaney, R.P., Proulx, W.R. et al. Absorbability of calcium from common beans, Journal of Food Science, Vol. 58, No. 6, 1401-1403, 1993.)

Sept. '95, It's Your Health, Canadian Living, Controversies, A New Look at Women's Health Issues.

"To stay healthy, a woman must be well-nourished. This means eating enough nutritious foods, including the recommended 2-4 servings of milk products, every day."

This doesn't leave much to the imagination. Eat your dairy product every day or you won't be well nourished.

Aug. '95, It's Your Health, Chatelaine, Tips on Vegging.

"Without them [dairy products] it's very hard to get enough calcium every day. Most other foods contain either too little or the calcium is in a form that's difficult to absorb."

It's Your Health, sent with mailing to RD's in Manitoba

"Dinosaurs could get the calcium they need from other food sources, as can other living animals with differently designed interiors."

Is Ms. MacDonald suggesting that only animals "with differently designed interiors" can rely on other food sources for their calcium?

"For humans to get the calcium they need from food without consuming milk products is extremely difficult. One of the reasons is bioavailability. The calcium in many other foods, like most fruit, vegetables and legumes, is poorly absorbed by the human digestive system. That is, it is not "bioavailable...There are of course, countless good, nutritional reasons for eating fruits, vegetables and legumes. Calcium just isn't one of them."

After being exposed to this kind of information for many years, it might just be possible that a person would get the idea that it is virtually impossible to meet one's needs for calcium without dairy foods.

2. "In general, the calcium from plant foods with high concentrations of either oxalate or phytate or both is poorly absorbed, relative to milk. Without milk products, calcium intakes in excess of 300 mg/day are difficult to achieve, but not impossible."

The absorption of calcium from plant foods is not as poor our critics would have us believe. The absorption of calcium from most vegetables (other than those rich in oxalates - spinach, chard, beet greens and rhubarb) is actually significantly higher than it is for milk. The calcium absorption from kale, broccoli, brussel sprouts, cabbage, Chinese greens, cauliflower, kohlrabi, mustard greens, turnips and turnip greens ranges from 52-67%, almost double that of milk and milk products. The calcium in legumes, nuts and seeds is absorbed at a rate of about 17-22%,1 or about two-thirds that of milk and milk products. While we are aware that plant foods are less concentrated sources of calcium than milk, we also know that the availability of the calcium from many of these foods is relatively good.

It is not accurate to say that "without milk and milk products, calcium intakes in excess of 300 mg/day are difficult to achieve, but not impossible". In studies that have assessed that calcium intake of pure vegetarians, there is not a single study, to our knowledge, that has found average calcium intakes to be below 300 mg/day. In fact, the average calcium intakes in 10 studies of vegans ranged from a low of 437 mg/day to a high of 1100 mg/day, with an average 627 mg/day.2-11

1. Weaver, C. and Plawecki, K. Dietary calcium: adequacy of a vegetarian diet. Am..Clin.Nutr. Vol 59(s), 1994.

2. Hardinge, m. and Stare, F. Nutritional studies of vegetarians. Am.J.Clin.Nutr. Vol.2:73-82, 1954.

3. Freeland-Graves, J., Brodzy, P. and Eppright, M. Zinc status of vegetarians. J.Am.Diet.Assoc. 77:655-661, 1980.

4. Calkins, B. Whittaker, D., Nair, P. et al. Diet, nutrition intake and metabolism in populations at high and low risk for colon cancer. Am.J.Clin.Nutr. 1:131, 1982.

5. Carlson, E., Kipps, M., Lockie, A. and Thompson, J. A comparative evaluation of vegan, vegetarian and omnivore diets. J.Plant Foods. 6:89-100, 1985.

6. Davies, G. Crowler, M. and Dickerson, J. Dietary fibre intakes of individuals with different eating patterns. Human Nutr. Appl. Nutr. 39A: 139-148, 1985.

7. Sanders, T. and Key, T. Blood pressure, plasma rennin activity and aldosterone concentrations in vegans and omnivore controls. Human Nutr: Appl. Nutr. 41A:204-211, 1987.

8. Draper, A. Lewis, J., Malhotra, N. and Wheeler, E. The energy and nutrient intakes of different types of vegetarians: a case for supplements? Br.J.Nutr. 69:3-19, 1993.

9. Lamberg-Allardt, C., Kärkkäinen, M., Seppänen, R. and Biström, H. Low serum 25-hydroxyvitamin D concentrations and secondary hyperparathyroidism in middle-aged white and strict vegetarians. Am.J.Clin.Nutr. 58:684-680, 1993.

10. Alexander, D., Ball, M. and Mann, J. Nutrient intake and haematological status of vegetarians and age-sex matched omnivores. Eur.J.Clin.Nutr. 48:538-546, 1994.

11. Janelle, K.$ Barr, S. Nutrient intakes and eating behavior scores of vegetarian and nonvegetarian women. J.Am.Diet.Assoc. 95:180-185, 1995.

Page 27

1. "This is true, but by focusing the paragraph on vitamin D and boron the reader learns only a fraction of the story. None of the well-documented problems with plant calcium -- namely the inherent oxalates, phytates and fibre which inhibit absorption -- are included." [referring to our section titled "Factors Contributing to Positive Calcium Balance" where vitamin D and boron are discussed]

The paragraph in question is pertains to factors contributing to positive calcium balance. These are important considerations for vegetarians trying to maintain calcium balance. Our critics say we do not talk about the "problems with plant calcium -- namely the inherent oxalates, phytates and fibre which inhibit absorption". These issues are raised on page 82 where we address the concern about oxalates, and in chapter 7 where the effects of phytates are discussed. According to Connie Weaver, fibre does not appear reduce calcium absorption. Dr. Weaver states, "Fiber does not appear to negatively affect calcium absorption, since calcium absorption was greater from kale than from milk."1

1. Weaver, C. and Plawecki, K. Dietary calcium: adequacy of a vegetarian diet. Am.Clin.Nutr. Vol 59(s):1238-1241, 1994.

2. "...calcium absorption from oxalate-free brassica vegetables such as kale, broccoli and bok choy, is at least as high as absorption of milk calcium and possibly slightly higher."

The calcium absorption from kale, broccoli and bok choy ranges from approximately 53-59%, as compared to a 32% absorption from milk. To classify this as "at least as high" or "possibly slightly higher" is not quite accurate -- indeed, the absorption is significantly higher from these plant foods. 1

1. Weaver, C. and Plawecki, K. Dietary calcium: adequacy of a vegetarian diet. Am.J.Clin.Nutr. Vol 59(s):1238-1241, 1994.

Page 28

1. " Protein first: This is a half truth. The problem only exists if calcium intake is inadequate. [referring to our statement "Calcium thieves such as excess protein or salt can cause substantial calcium losses."]

This is not a "half-truth"; but a well accepted scientific fact -- protein does increase calcium losses.1-6 Of course, increasing calcium intake will help to compensate for those losses, but it is important to recognize, particularly for people who consume little or no dairy products, that excess protein increases calcium requirements.

1. Weaver, C. and Plawecki, K. Dietary calcium: adequacy of a vegetarian diet. Am..Clin.Nutr. Vol 59(s):1238-1241, 1994.

2. Heaney, R. Protein intake and the calcium economy. J.Am.Diet.Assoc. 1993: Vol.93;No.11:1259-1260.

3. Zemel, M. Calcium utilization: effect of varying level and source of dietary protein. Am.J.Clin.Nutr. 48:880-883, 1988.

4. Hegsted, M. Schuette,S., Zemel, M. and Linkswiler, H. Urinary calcium and calcium balance in young men as affected by level of protein and phosphorus intake. J. Nutr. 111:553-562, 1981.

5. Riggs, B., Kelly, P., Kinney, et al. Calcium deficiency and osteoporosis. J. Bone Joint Surg. 49:915-924, 1967.

6. Recker, R., Davies, M., Hinders, S, et al. Bone gain in young adult women. JAMA. 268:2403-2408, 1992.

2. "Moreover, there is far from an excessive amount of protein in milk." Our critics go on to defend the protein content of milk as not being a problem. They add: "Dietary proteins such as milk and cheeses, do not cause calcium loss in controlled studies in humans. To imply otherwise is misleading...It should be noted that calcium to protein ratio in milk and hard cheeses in the range of 36:1. Therefore, milk should not be avoided because it contains protein. The abundance of calcium relative to protein make dairy foods an ideal source of protein and calcium for the vegetarian diet."

These statements frankly imply that we advise our readers to avoid milk because it contains protein and will therefore cause calcium loss. We did not and would not tell our readers that the protein in milk is cause for concern, because we do not believe that it is. In fact, we do not tell our readers to avoid milk for any reason. We are well aware of the protein to calcium ratio in milk and readily acknowledge that dairy products are an excellent source of calcium. In addition, milk provides high quality protein, which can be an important nutritional advantage, particularly during the growing years. We had no intention of encouraging readers to avoid milk, rather to help readers who do not use dairy products to plan a nutritionally adequate diet.

We find it very disturbing that a document written by the dietitians employed by the Dairy Bureau of Canada would purposefully lead the reader into questioning our professional credibility based a false perception of what they assume our position to be. We said nothing that would even remotely indicate that we hold the view that milk should be avoided because it contains protein.

3. Table # 1. This table showing sulfur amino acid content as a percentage of total protein is misleading. It is not the percent of total protein as sulfur containing amino acids that is important, but rather the total sulfur-containing amino acids consumed.

Whereas beef protein is only 3.3% methionine and cysteine, it contains 1166 mg of sulfur-containing amino acids per serving as compared to rice with 4.4% methionine and cysteine, but only 79 mg of methionine and cysteine per serving.

1. Pennington, J.A. Bowes and Church's Food Values of Portions Commonly Used. 16th Ed. Philadelphia: Lippincott Company, 1993.

Previous Page | Next Page