Possible problems with determining nutrient requirements by mass balance studies

Determining the minimum daily requirement of a nutrient seems simple enough – just determine the mass balance, that is, how much of a nutrient is needed to replace obligatory daily losses, and do the experiment over a sufficiently long period of time to have confidence in the results.

However, this assumes that all nutrients in that particular nutrient’s ADME network are in place at optimal levels – highly unlikely in modern America.

Consider the absurdity of trying to define the minimum daily calcium requirement in a person with a clear deficiency of magnesium. Such a person inappropriately excretes calcium in his urine because magnesium is a nutrient in calcium’s ADME network.

The iron requirement in a person who is copper deficient cannot be defined, so important is copper in iron’s distribution (copper puts the D in iron’s ADME network; at least 3 copper-requiring proteins are involved in moving iron around the body).

In addition, it may be that some, many, or even all nutrients need to circulate throughout the body to grease the body’s gears so to speak – for these nutrients, the minimum daily amount needed is that amount necessary to maintain its balance, given optimal levels of all ADME nutrients, PLUS the amount needed to circulate through the body each and every day to keep everything running smoothly and everything else in balance.

Sodium, chloride, and vitamin C are almost certainly nutrients that need to pass throughout the body each and every day for optimal health. Is this true of all other nutrients?

Notice that my idea that the vitamin C requirement is the sum of the amount needed to maintain vitamin C balance PLUS the requirement that must circulate through the body comes close to Pauling’s idea that very high doses (multiple grams) of vitamin C are useful in preventing atherosclerosis – circulating high levels of C throughout the body hour by hour each day would keep the serum level consistently high and consistently protective against oxidative damage to key structures, provided that nothing untoward is making the vitamin C act like a pro-oxidant, in which case the vitamin C is likely attacking the culprit by bleaching it.

Why do I think that sodium chloride needs to cycle throughout our bodies?

Reason 1: Because our craving for salt is so much higher than what is needed to replace losses. This craving, present even in reasonably well nourished people, suggests the body has needs for salt that are greatly in excess of replacing insensible losses of sodium and chloride. So important is salt that it must even be added to sweets to make them taste better – first and foremost, if our taste for salt is not satisfied, we cannot thoroughly enjoy the sweetness of a sweet treat.

Reason 2: we absorb so much more sodium chloride than we need to maintain mass balance. Reasonable explanation: sodium chloride needs to circulate throughout the body. To maintain optimal health, we need more sodium chloride per day than what merely replaces daily losses.

Speculation: every essential nutrient is an essential nutrient in at least one other essential nutrient’s ADME network. If true, then sodium and chloride, each of which are essential nutrients, are essential nutrients in other essential nutrients’ ADME networks, and they may need to be temporarily at higher activities at particular locations for optimal bodily function. The same goes for vitamin C and who knows how many other essential and conditionally essential nutrients.

What evidence is there that vitamin C needs to circulate?

The evidence is a bit speculative:

Consider the goat, which is about our size. The goat makes about 13 grams of vitamin C a day. If its total body pools are like ours, about 1.5-3.0 grams, and its rate of turnover of vitamin C is about the same as ours, about 2%-4% per day, then as little as 4% of 1500-3000 mg (60-120 mg) is all that is needed to maintain homeostasis under the worst of conditions. Clearly the goat is making more than it “needs” Biological systems do not in general make 100 times more of something than they need to. So why make so much? Probably because something comparable to this amount of vitamin C, 13 grams, which is roughly 200 times the human RDA (60 mg/day, which is based on balance studies with a generous overage for safety), in all likelihood needs to circulate through the goat’s body each and every day. Is it not likely the same is true for us?

In addition, why does even a person with good vitamin C status still absorb grams of supplemental vitamin C only to excrete nearly all or all but what he/she needs to replace losses? Reasonable explanation: vitamin C needs to circulate throughout our bodies. Replacing losses is not enough. The assumptions behind mass balance studies are or may well be false.

Also, why does the body absorb so much more than it needs of supplemental B vitamins only to excrete what it does not need? Is there something not accounted for in current models of nutrition?

Could atherosclerosis be all but non-existent in us, as Pauling and Rath suggested, if we circulated many grams of vitamin C a day in proper and multiple doses throughout our bodies?

Has the US government misconstrued nutritional science, even when it is interpreting a “simple” balance study?

Does this apply even to cholesterol? Why does the body absorb up to a gram a day of additional cholesterol while remaining fully committed to making a gram a day?

Re poisons: In cases of accidental poisoning, why do we absorb so much more arsenic than we need (we need perhaps just 12 micrograms/day out of just 48 micrograms/day in our food supply)? I assume because mechanisms did not evolve to protect us from arsenic, which is not abundant in food, and so many other poisons. But mechanisms did evolve to protect us from iron poisoning, and food (10-20 mgs/day ingested) does contain enough iron to poison us, if we did not exclude all but 1-2 mg/day, although no known mechanism evolved to protect us from iron overload if the former mechanisms failed, as they do in hereditary hemochromatosis. Is the same true of salt, vitamin C, and the B vitamins? Mechanisms did not evolve to protect us from over-absorption of the minerals and the vitamins, and the over-absorption did not prove to be anywhere near as harmful as over-absorption of arsenic does, and iron would, if mechanisms did not exist to protect us from iron overload due to over-absorption?


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