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

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

Page 34

1. "The authors' bias is evident as they fail to point out that phytate found in whole grain products and legumes is the major dietary inhibitor of zinc." [referring to a quote regarding the potential for excess calcium to bind the mineral zinc.]

This quote was taken from the section titled "Calcium Supplements". We were discussing the potential negative impact of using calcium supplements in excess. It is important for people to realize that while a supplement may be beneficial under certain circumstances, it is important not to abuse it. When our critics point out our so-called "bias" (ignoring phytate as a zinc inhibitor), they demonstrate that they have not read Becoming Vegetarian. We discuss phytates and the inhibition of zinc in several places:

"Phytates, particularly in raw foods such as wheat bran, have been a concern because they can bind a portion of the iron, zinc and calcium, making the minerals unavailable for absorption." (page 63)

"When people take calcium supplements together with plant foods, a zinc-calcium-phytate complex is formed in which the zinc is tightly bound and not available for absorption." (page 69)

"...excessively high ratios of phytate to zinc can reduce zinc absorption; this can occur when unleavened bread is a mainstay or when substantial amounts of raw wheat bran are added as a supplement. The addition of raw wheat bran to a plant-based diet is neither necessary nor advisable." (page 69)

"The absorption of minerals is affected by the amount of phytate present in the intestinal contents. If the diet contains marginal levels of minerals - such as iron, calcium, magnesium and zinc - the extra phytate introduced with the bran might bind enough of the minerals to cause mineral deficiency." (page 128)

Page 35

1. "When Canadians have trouble consuming the recommended two - four serving of milk products how likely is it they'll start eating seaweed?" [referring to a quote about some natural sources of vitamin D].

In the vitamin D section of the text we have a short paragraph on natural food sources of vitamin D following a discussion of vitamin D-fortified foods. By taking our words out of context, our critics make it sound as though we were advising people to rely on seaweed as a vitamin D source. Here is what was actually said:

"There is little doubt that before the era of vitamin supplementation and food fortification, sunlight was the major provider of vitamin D for most of the world's population. Vitamin D is naturally present in few foods. Fish oils are a notable exception...The exposure of certain plant foods to ultraviolet light has also been demonstrated to produce a form of vitamin D (vitamin D2). for example, certain seaweeds, dried in the sun, have shown vitamin D2 activity."

In our discussion about getting enough vitamin D from foods, the only foods we recommend as reliable sources for vegetarians are those foods fortified with this nutrient.

2. "Why eliminate a perfectly acceptable food source from the diet in order to follow a restrictive dietary regimen? Only two pages before, in their discussion of calcium, the authors acknowledged that "supplements...should not be assumed to be adequate replacements for real food." If vegan can't get vitamin D from their diets, perhaps they should take a page from their lactovegetarian brothers and sisters and admit dairy products back into their diets. Two pages later, this statement appears: "You can choose sunlight, fortified foods, supplements or a combination." We have an excellent suggestion for a vitamin D-fortified food...Milk!"

This paragraph beautifully illustrates our motivation for including the section "'Reasons why people limit or eliminate dairy products". What our critics don't seem to understand is that dairy foods are far from being "a perfectly acceptable food source" for vegans. Indeed, dairy foods are as unacceptable to vegans as meat is to vegetarians. Making these kinds of statements demonstrates a lack of regard for the values and beliefs of this group of people -- we find it both offensive and completely inappropriate from health professionals.

Milk is an excellent source of vitamin D because it is fortified with that nutrient. An excellent suggestion for a vitamin-D-fortified food for a vegan would be a fortified non-dairy beverage, such as those widely available in the U.S., but as of yet are not permitted in Canada. Thus, Canadian vegans must rely primarily on sunshine and supplements until such time as these laws are changed.

2. "Unfortified soy beverages contain only about half of the phosphorus, 40% of the riboflavin, 10% of the vitamin A, 3% of the calcium, and none of the vitamin B12 found in a serving of cow's milk...The amino acid profile of milk is ideal for calcium utilization: it has a high proportion of lysine which enhances calcium utilization and a low proportion of methionine and cysteine, which decrease calcium utilization."

While the Dairy Bureau nutritionists spend some time extolling the virtues of cow's milk in favour of soy milk, there are a few points they left out:

i/ phosphorus -- we get plenty of phosphorus in the diet, and possibly even too much1,2. Providing only half the phosphorus of cows' milk is an advantage, not a disadvantage.

ii/ vitamin A -- vitamin A is rarely of concern in a plant-based diet. However, there is no reason it could not be added to non-dairy beverages, just as it is added to low fat milks.

iii/ calcium -- While there are some unfortified soy beverages that are low in calcium content, several of the more popular beverages available in Canada provide considerably more than the 3% of the calcium (9 mg) in milk mentioned by the Dairy Bureau dietitians. The calcium content per cup is as follows:

· Edensoy -- 95 mg (32% of the calcium in milk )

· Vitasoy -- 76 mg (25% of the calcium in milk)

· Semblence -- 200 mg (67% of the calcium in milk)

iv/ protein -- Our critics state that the amino acid profile of milk is ideal for calcium utilization because it contains a high proportion of lysine and a low proportion of methionine and cysteine. The implication is that this is an important advantage over soy beverages. In fact, the lysine, methionine and cysteine content of soy milk vs cow's milk are as follows3:

v/ There are several important advantages of soy milk over cow's milk. If the government permitted the fortification of soy milk as it permits the fortification of cow's milk, the advantages would be even more pronounced.

· soy milk provides less saturated fat than cow's milk (soy - 0.5 g; whole cow's 5.1 g; 2% cow's - 2.9 g)

· soy milk provides more essential fatty acids than cow's milk (soy - 2.0 g; cow's < 0.2 g)

· soy milk is cholesterol-free, while cow's milk contains 34 mg of cholesterol per cup.

· soy protein lowers total and LDL -cholesterol levels without adversely affecting beneficial HDL, while cow's milk protein raises blood cholesterol levels.

· soy foods, including soy milk are one of the few foods that provide appreciable amounts of phytoestrogens such as genestein and daidzen which have been demonstrated to be anticarcinogenic and antiatherogenic.

1. Calvo, M. and Park, Y. Changing phosphorus content of the U.S. diet: potential for adverse effects on bone. Amer.Inst.Nutr. 1168(s)-1180(s), 1996.

2. Anderson, J. Calcium, phosphorus and human bone development. Amer.Inst.Nutr. 1153(s)-1158(s), 1996.

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

Page 36

1. "According to these studies, the chart in Becoming Vegetarian, the origin of which is unknown, appears to be inaccurate." [referring to our chart on months without vitamin D production in three large centres]. "A study by Holick evaluated the effect of season and time of day in Boston (42º N)..." [a 1995 study is quoted].

The sources of our information on vitamin D were the most up to date available at the time of writing our manuscript (our book was published in 1994, a year before the 1995 study quoted by our critics). The primary source of our information was research by Dr. Holick and his colleges published in 1992.1 To insure that this material represented the most up-to-date information available, we contacted Dr. Holick personally. Dr. T.C. Chen, of Dr. Holick's laboratory reviewed our chapter, with attention to the section on vitamin D. In 1995, a year after our book was released, further research prompted Dr. Holick's lab to issue modified guidelines which slightly differed from the guidelines they previously advocated.2"

1. Lu, Z., Chen, T.C., Kline, L., Markstad, J., Pettifor, J., Ladizesky, M., Mautalen, C. and Holick, M. Photosynthesis of previtamin D in cities throughout the world. Biologic Effects of Light, Proceedings of a Symposium, Atlanta Georgia, USA and Walter de Gruyter, Berlin, New York, USA, 1992.

2. Holick, M. Environmental factors that influence the cutaneous production of vitamin D. Am.J.Clin.Nutr. 61(suppl):638(s)-45(s), 1995.

Page 38

1. "According to an independent study, the figure of 225% appears to have been derived improperly from millimoles of riboflavin, not from milligrams as it should have been." [referring to mg riboflavin in our vegan menu].

The Dairy Bureau nutritionists went to great lengths to determine why our figures for riboflavin were so much higher than the figures submitted by their firm -- had they simply asked us, we would have been more than happy to provide them with that information. The reason our values were so different were due to the fact that our analysis included nutritional yeast, an optional ingredient in the egg salad sandwich. Red Star T-6635+ nutritional yeast powder provide 1.6 mg of riboflavin per teaspoon. Thus 1/2 a teaspoon, as would be found in an eggless egg salad sandwich would provide 0.8 mg of riboflavin (1.2 mg in 1 1/2 sandwiches consumed by the 170 pound vegan). While nutritional yeast is an optional ingredient in this recipe, we strongly encourage its use, and do specifically state that it is included in this analysis on page 145 or the book.

We define the recommended intake for riboflavin (earlier in the paragraph) as 0.5 mg per 1000 calories consumed.1 Thus the 130 pound vegan would need about 1.1 mg of riboflavin/day and the 170 vegan would need about 1.5 mg. At 225% of RNI's they would need 2.5 and 3.3 mg respectively. We used two programs -- Nutritionist IV and Nutricom to arrive at the values we listed, and these figures were checked a minimum of 3 times each.

1. Health and Welfare Canada. Nutrition Recommendations: The report of the Scientific Review Committee. Ministry of Supply and Services Canada. Page 106, 1990.

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