Just watched this interesting lecture:
It suggested that a diet high in milk / animal protein actually increases the risk of bone fractures.
asked byCaveMan_Mike (3275)
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on November 13, 2016
at 11:49 PM
This is the usual pro-vegan nonsense that's been on the web for years now. Whenever you see someone claiming that certain foods are acidifying or alkalanizing, you're dealing either with someone who doesn't know any better, or worse are a charlatan. Yes, it's true that our kidneys do maintain pH balance in our bloodstream - if they didn't, we'd be dead. No, they don't do it via calcium, they mostly do it via bicarbonate (carbon). No, meat isn't acidifying. We use acid to break down meat into amino acids. Meat digestion and breakdown creates ammonia - which is alkaline, and we dispose of it by converting it to urea. see: http://fitsweb.uchc.edu/student/selectives/TimurGraham/Acid_Buffering.html http://holisticsquid.com/the-alkaline-diet-myth/ https://chriskresser.com/the-ph-myth-part-1/
on November 14, 2016
at 06:10 AM
A problem with meat as opposed to cheese or milk is the low calcium content. The calcium:phosphorus ratio is extremely important in animal feeding, especially for carnivores and this has been known for many decades, ask any veterinarian, and is why meat based dog or cat food always have added calcium, typically bones, to balance the phosphorus, usually a 1:1 to 1.4:1 Ca:P ratio. And it´s not about an absolute calcium requirement as with humans, the requirement is proportional with the meat intake. Although if vitamin D intake is adequately high, a lower ratio may be possible.
This is also seen in the milk of various species which almost always have a calcium:phosphorus ratio above 1. In human milk and other primate milk it´s typically around 1.5-2:1. Also calcium content seems to be closely related to protein. So for example in human milk, in sheep milk and in dog milk, the calcium (in mg) to protein (in gram) ratio is around 30, even though the dog milk supplies 5 times more protein per calorie. And so 2500 kcal dog or sheep milk may supply 3000-5000 mg calcium, but the requirement to build the bones may be just 10% of this, so obviously calcium has other roles. It is there for a reason.
Anyone having sleep problems (unrestful sleep, waking up exhausted, having sleep apnea etc) should look into the Ca:P ratio and be cautious about eating an excess of meat without any extra calcium, especially in the evening.
Ironically, whole grains and seeds (and to a lesser extent nuts) are usually very high in phosphorus but low in calcium, so the argument for avoiding meat and instead eat seeds and whole grains, doesn´t make so much sense.
This has suggested to be a major cause of poor health, including short stature, after humanity started to eat cereal grains. But many seeds are far worse in terms of phosphorus/phytic acid than grains. And Kresser seems to be pro seeds and legumes. So apparently he doesn´t understand the calcium/phosphorus thing and the anti-nutrients in seeds and legumes. There are ways used in some traditional cultures to treat the seed foods with calcium etc to make them a more suitable food for consumption. The ancient Indian civilization seems to have cooked corn with lime stone (calcium hyroxite) for example. Corn is virtually absent in calcium.
Loren Cordain points out in the paper «Cereal Grains: Humanity’s Double-Edged Sword» (http://www.direct-ms.org/pdf/EvolutionPaleolithic/Cereal%20Sword.pdf) that:
cereal grains have a Ca/P ratio which is quite low and which can negatively impact bone growth and metabolism. Consumption of a large excess of dietary phosphorus, when calcium intake is adequate or low, leads to secondary hyperparathyroidism and progressive bone loss . The recommended, ideal Ca/P ratio is 1:1, whereas in the United States it averages 0.64 for women and 0.62 for men . In addition to the unfavorable Ca/P ratio, cereal grains maintain a quite low Ca/Mg ratio (averaging 0.19 from table 4) which also favors net Ca excretion, since imbalances in Mg intake relative to Ca decrease gastrointestinal absorption and retention of Ca [73, 74]. Because of the high phytate content of whole grain cereals much of the calcium present is unavailable for absorption because the phytate forms insoluble complexes with calcium . The net effect of a low calcium content, a low Ca/P ratio, a low Ca/Mg ratio, and low bioavailability of calcium via a high phytate content frequently induces bone mineral pathologies in populations dependent upon cereal grains as a staple food. In populations where cereal grains provide the major source of calories, osteomalacia, rickets and osteoporosis are commonplace [76–79]. Cereal grains have been shown to cause their rachitogenic and osteomalacia-producing effects in spite of the presence of adequate sunshine . Further, substitution of leavened white breads of lower extraction for unleavened whole grain breads improved biochemical symptoms in patients with rickets or osteomalacia .
Consumption of high levels of whole grain cereal products impairs bone metabolism not only by limiting calcium intake, but by indirectly altering vitamin D metabolism. In animal studies it has been long recognized that excessive consumption of cereal grains can induce vitamin D deficiencies in a wide variety of animals [81–83] including primates . Epidemiological studies of populations consuming high levels of unleavened whole grain breads show vitamin D deficiency to be widespread [85–87]. A study of radiolabelled 25-hydroxyvitamin D3 (25(OH)D3) in humans consuming 60 g of wheat bran daily for 30 days clearly demonstrated an enhanced elimination of 25(OH)D3 in the intestinal lumen . The mechanism by which cereal grain consumption influences vitamin D is unclear. Some investigators have suggested that cereal grains may interfere with the enterohepatic circulation of vitamin D or its metabolites [84, 88], whereas others have shown that calcium deficiency increases the rate of inactivation of vitamin D in the liver . This effect is mediated by 1,25-dihydroxyvitamin D (1,25(OH)2D) produced in response to secondary hyperparathyroidism, which promotes hepatic conversion of vitamin D to polar inactivation products which are excreted in bile . Consequently, the low Ca/P ratio of cereal grains has the ability to elevate PTH which in turn stimulates increased production of 1,25(OH)2D which causes an accelerated loss of 25-hydroxyvitamin D.
As for protein regulating acid/base in the kidneys via ammonium, I think it´s mainly glutamine which has this role (see: http://www.anaesthesiamcq.com/AcidBaseBook/ab2_4.php,
https://en.wikipedia.org/wiki/Glutamine). This is also Cordain´s point in the book «the paleo diet for athletes» from 2012. Eating more potassium foods like fruits and vegetables (which supplies typically potassium bicarbonate/carbonate - so they are carriers of the carbon) would then help «spare» glutamine according to him.
Chris Kresser seems to believe that protein in excess is only harmful because of the methionine and that high protein diets are fine if they are balanced with enough glycine, found in certain parts of the animal. This doesn´t make so much sense, for example ground beef has a higher glycine:methionine ratio than most organ meats, the exception being skin. The whole carcass actually will have a lower glycine:methionine ratio than ground beef. The ratio in ground beef is also about twice as high as human milk or eggs.
However gelatine or collagen (just as egg whites), will supply protein without much phosphorus, as well as some glutamine, and that could be very helpful for the kidneys if calcium intake is low.
And so I think it´s possible that the link between protein and shortened lifespan may have more to do with excessive phosphorus which is not balanced by enough calcium (and other alkaline minerals), or that there´s a deficiency in vitamin D, which is needed to balance these minerals. Organ meats like liver or kidney will however supply vastly more phosphorus than muscle meat.
An excess of phosphorus seems to be the cause of so many problems, such as inflammation or atherosclerosis. Even elevated serum phosphorus within the normal range for people with normal kidney function, is associated with increased risk of cardiovascular disease. But it is worth noting that an excess of calcium, especially the carbonate type can cause things like milk alkali syndrome which is very dangerous. So it´s all about balance. Also excess of magnesium (carbonate) may cause this condition.