Posted by Larry Hoover on March 2, 2005, at 12:18:42
In reply to Animal Rights, posted by alexandra_k on February 21, 2005, at 19:56:04
> There can be no defence of eating flesh in terms of satisfying nutritional needs, since it has been established beyond doubt that we could satisfy our need for protein and other essential nutrients far more efficiently with a diet that replaced animal flesh by soy beans, or products derived from soy beans, and other high-protein vegetable products.
Sorry, I'm rather slow to join this discussion, but I hope the following is food for thought:
It would seem that one of the predicate assumptions for the conclusion that eating animal flesh is unethical is that adequate nutrition is available from a vegetarian or vegan diet. Not only has that never been demonstrated, it is factually impossible, based on some other assumptions.
The United States Department of Agriculture has published extensive analyses of food nutrient content, both for pure foods, and for processed foods. Employing those data, and assuming a caloric intake appropriate to maintain a stable weight, it is not possible to select *any* diet which simultaneously meets all RDA (recommended daily allowance) levels for nutrients for which an RDA is established. Although the belief that a "balanced diet" will provide all required nutrients is widespread, I have never found any evidence that supports that belief. I would be glad to be proven wrong on this, but, as I said, the evidence is lacking.
It's important to understand what is meant by terms like RDA (and related measures such as DRI (daily recommended intake)).
The core determination is the EAR, the Estimated Average Requirement. That's the 50th percentile of overt deficiency risk, based on the seven-day averaged intake of a nutrient. At the EAR, there are equal numbers of individuals showing overt deficiency symptoms, and equal numbers not. The RDA is two standard deviations above the EAR. By definition (normal distribution), that captures all individuals up to the 97.5th percentile. At the RDA level of intake, 1 in 40 *healthy and normal* subjects is still exhibiting overt deficiency symptoms. There is no consideration for adverse health states, nor for optimal intake. Nor are "normal" or "healthy" defined.
For a visual representation, see the graph at:
http://books.nap.edu/books/0309071836/html/24.html#pagetopYou'll note that adverse health effects are still expected if someone meets the RDA for that given nutrient (i.e. risk of inadequacy is non-zero). And way off to the right is the Upper Limit, that point where intake is so high that the risk of toxic effects starts to rise from zero. Just from looking at the graph, you can see that it's better to exceed the RDA for nutrient intakes, so long as you stay below the UL.
For some nutrients, there is no known Upper Limit. In other words, you'd have to really go out of your way to obtain any toxic effects from them. For others, the Upper Limit is set with some very conservative safety factors in mind. For example, the safety factor for vitamin E is 36. That means you'd have to take 36 times the recommended Upper Limit for there to be any real risk of toxic effects. (And, it so happens, the toxic effects that do arise from excess vitamin E are likely due to vitamin K deficiency, which really has nothing to do with vitamin E in the first place).
There are other curves (all based on what is called the "normal curve" of statistical distribution) which have been used to show the various aspects of nutrient deficiency and excess.
http://www.nutrition.org/cgi/content/full/133/5/1563S/FIG2There are three aspects of deficiency. The most obvious are overt syptoms of deficiency, labelled here as "clinical effects". This is the same curve I referenced above, with respect to RDA. To its right (higher intakes) are curves representing measurable biochemical effects of subclinical intensity, and measurable biochemical effects of no clinical relevancy. The dotted curves showing AROI "acceptable range (of daily) oral intake", lie completely to the right of the intake defined by RDA. In other words, 100% of all subjects would show no signs of overt or covert deficiency or toxic effects within the AROI range. Optimization of health is the limiting character of AROI, whereas RDA is wholly inadequate. Despite that *defined* inadequacy, a balanced diet cannot even meet that threshold.
Here are the only published analyses of diet adequacy that I have ever found. They demonstrate that when calories are appropriately limited, even a balanced diet is inadequate.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6703646
Ann Nutr Metab. 1984;28(1):11-23.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=3654115
Int J Vitam Nutr Res. 1987;57(2):225-30.So what? People have surviving to ripe old ages, nothwithstanding dietary analysis. What's the big deal?
Cancer.
Bruce Ames (the same Ames of the Ames Test for mutagenicity) has laid it all out.
http://www.nutrition.org/cgi/content/full/133/5/1544S
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11295149
Mutat Res. 2001 Apr 18;475(1-2):7-20.What is striking is that a significant number of these key anti-cancer nutrients are also generally deficient in vegetarian (expecially vegan) diets. That said, even omnivores (well, American omnivores, for certain) do not obtain anywhere near sufficient iron or zinc from diet.
The United States government has funded major investigations into the relationship between typical diet and health parameters, under the name NHANES (National Health and Nutrition Examination Survey), now in its third data collection cycle. From those surveys, we obtain the following data:
Iron and zinc table:
http://www.nutrition.org/cgi/content/full/131/8/2177/T5Even with fortification of foods, more than half of adults fail to meet the RDA for iron or zinc.
Zinc table:
http://www.nutrition.org/cgi/content/full/130/5/1367S/T4In this table, "Adequate Intake" (which has no scientific basis; it is an estimate based on an estimate) is defined as only 77% of RDA, yet only 54% of the population meets even that target (despite overconsumption of meat, a major source). In the full-text of that article, it is suggested that only 2% of the population meet or exceed the RDA for zinc, and every one of those uses a supplement.
I repeat. Only 2% of Americans meet or exceed zinc RDAs, and only if taking a supplement. Moreover, there is an unexamined confound, bioavailability. Plant-based mineral uptake is substantially inhibited by constituents of the plants themselves. Direct competition due to binding by oxalic acid or phytic acid is exacerbated by physical compartmentalization within soluble fiber or adhesion to insoluble fiber. Uptake of minerals can be as little as 1% of the amount determined by elemental analysis of the plant mineral content.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=1910521
Estimating adequacy of zinc intake:
http://www.nutrition.org/cgi/content/full/133/5/1563SA diet analysis only provides you with crude intake information, in any case. It is fallacious to equate intake with uptake. Consider, for zinc alone, the effect of a single dietary variable, phytate intake. From the text above: "The WHO committee set three levels of zinc absorption based on the P:Z of three diet types: P:Z < 5 (representing refined diets or semipurified formulas), 50% absorption; P:Z 5-15 (representing mixed diets or refined vegetarian diets), 30% absorption; P:Z > 15 (unrefined diets, negligible animal protein), 15% absorption. The data used were derived from studies measuring zinc absorption from single test meals, as well as from total diets, although the availability of the latter study types were limited at the time the estimates were made."
Bioavailability is what sets animal flesh apart from plant-source foods. All biota are bioaccumulators. Plants bioaccumulate from soil (with the help of microbes). If that was not the case, would we not just eat soil? Animals are even better nutrient bioaccumulators than are plants. Moreover, the form (particularly with respect to minerals and B-vitamins) of those nutrients are generally more bioavailable (as percent uptake/utilization) than are the identical plant-based nutrients. Whether an individual can survive solely on plant-based nutrient intake is not determinable from any of the data available to us. The normal curves of nutrient requirement have high inter-personal variability. Some people may do quite well on what is statistically an inadequate diet, as it is adequate for their own specific needs. However, it is not possible to generalize from a specific case of adequacy to any other individual. That is the failure of the assumption that vegetarian diets can be adequate sources of nutrition.
For someone contemplating a vegetarian diet, there are some specific considerations to bear in mind. The most problematic micronutrients to obtain are calcium, iodine, iron, zinc, selenium (in some countries, based on soil content), vitamin B12 (cobalamin), vitamin B2 (riboflavin, which itself is essential for zinc and iron uptake from the gut), vitamin B6 (pyridoxine), and vitamin D. Evidence is accumulating that the macronutrient long-chain omega-3 polyunsaturated fatty acids DHA and EPA are also conditionally essential. Here are some abstracts which detail the magnitude of those problems.
B-vitamins generally:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=1797957
Vitamin B12:
vitamin D
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8237875
Iron
Selenium
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8546880
Iodine
General nutrition of vegetarian diet:
Nutritional importance of animal source foods:
http://www.nutrition.org/cgi/content/full/133/11/3932SOn mineral bioavailability:
http://www.ajcn.org/cgi/content/full/78/3/633SOn vegetarian diet and long-chain omega-3 polyunsaturates:
http://www.ajcn.org/cgi/content/full/78/3/640Shttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7609607
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=9637947
To your health,
Lar
poster:Larry Hoover
thread:461535
URL: http://www.dr-bob.org/babble/social/20050224/msgs/465446.html