The next excerpt comes from Dr. Campbell’s Complete: Rethinking the Science of Diet, launched 10 years in the past. It explores how reductionist measures in diet fail to account for the variability of pure processes. To study extra about reductionism and its different – wholism – read our webpage on Whole.
Wrench #1: The Knowledge of Our Our bodies
Are you sitting down? As a result of I would like to clarify one thing that nearly nobody acknowledges about diet: there may be nearly no direct relationship between the quantity of a nutrient consumed at a meal and the quantity that really reaches its major website of motion within the physique—what known as its bioavailability. If, for instance, I eat 100 milligrams of vitamin C at one meal, and 500 milligrams at a second meal, this doesn’t imply that the second meal results in 5 instances as a lot vitamin C reaching the tissue the place it really works.
Does this sound like unhealthy information? To reductionists, it definitely does. It signifies that we are able to by no means know precisely how a lot of a nutrient to ingest, as a result of we are able to’t predict how a lot of it is going to be utilized. Uncertainty: a reductionist’s worst nightmare!
Really, this is excellent information. The rationale we are able to’t predict how a lot of a nutrient might be absorbed and utilized by the physique is that, inside limits, it relies on what the physique wants at that second. Isn’t that incredible? In additional scientific language, the proportion of a nutrient that’s digested, absorbed, and supplied to numerous tissues and the cells in these tissues is generally depending on the physique’s want for that nutrient at that second in time. This want is continually “sensed” by the physique and managed by a wide range of mechanisms that function at varied levels of the “pathway,” from nutrient ingestion to nutrient utilization. The physique reigns supreme in selecting which vitamins it makes use of and which it discards unmetabolized. The pathway taken by a nutrient usually branches, and branches additional, and branches additional once more, main the nutrient by means of a maze of reactions that’s much more complicated and unpredictable than the easy linear mannequin of reductionism would counsel.
The proportion of ingested beta-carotene that’s really transformed into its commonest metabolite, retinol (vitamin A), can range as a lot as eight-fold. The proportion transformed additionally decreases with growing doses of beta-carotene, thus retaining absolutely the quantities which might be absorbed about the identical. The share of calcium absorbed can range by a minimum of two-fold; the upper the calcium consumption, the decrease the proportion absorbed into the blood, making certain sufficient calcium for the physique and no extra. Iron bioavailability can range anyplace from three-fold to as a lot as nineteen-fold. The identical holds true for nearly each nutrient and associated chemical.
In short, the connection between quantity consumed and quantity used for nearly all vitamins is just not a linear relationship. Though many professionals know this, few totally admire the importance of this complexity. It means nutrient databases are usually not practically as helpful as one may suppose. It additionally means reductionist supplementation with massive doses of discrete vitamins doesn’t assure the utilization of these vitamins. (In reality, our digestive processes are so complicated and dynamic that super-dosing with a single nutrient all however ensures an imbalance of another vitamins, as we’ll see in Wrench #3 later on this chapter.)
Wrench #2: The Variability of Meals
Not understanding how a lot of a given nutrient might be utilized by the physique is barely a part of our uncertainty. The nutrient content material of the meals we eat themselves varies way over most of us understand. Have a look at the analysis simply on one antioxidant vitamin, beta-carotene (and/or its associated carotenoids). Beta-carotene content material in numerous samples of the identical meals is thought to range three- to nineteen-fold, though it could be as much as forty-fold or extra, as was reported for peaches. That’s proper—you possibly can maintain a peach in every hand, and the one in your proper hand may simply include forty instances extra beta-carotene than the one in your left, relying on issues like season, soil, storage, processing, and even the unique location of the fruit on the tree. And beta-carotene is way from the one instance. The “comparatively steady” calcium content material of 4 sorts of cooked mature beans (black, kidney, navy, pinto) ranges 2.7-fold—from 46 to 126 mg—per cup.
The variation in meals nutrient content material and the variation in nutrient absorption and utilization by the physique compound one another. A easy train may assist to make the purpose. Suppose the quantity of beta-carotene in a carrot varies about four-fold, and the quantity of this unsure proportion that’s then absorbed throughout the intestinal wall into the bloodstream varies one other two-fold. Which means the quantity of beta-carotene theoretically delivered to the bloodstream from any given carrot on any given day may vary as a lot as eight-fold.
These are large however unsure variations, and whether or not these ranges are two- or forty-fold, the final word message is identical: With the consumption of any explicit meals at any explicit second, we can’t know with any precision how a lot of any nutrient is definitely accessible to our our bodies, or how a lot our our bodies really use.
Wrench #3: The Complexity of Nutrient Interactions
However wait—there’s extra uncertainty! Chances are you’ll be shocked to study that the three vitamins talked about above can modify each other’s actions. Calcium decreases iron bioavailability by as a lot as 400 p.c, whereas carotenoids (like beta-carotene) enhance iron absorption by as a lot as 300 p.c. Theoretically, in evaluating a high-calcium, low-carotenoid weight loss plan with a low-calcium, high-carotenoid weight loss plan, we would see an 800-1,200 p.c distinction in iron absorption. However even when this theoretical variation have been solely 100-200 p.c, that is nonetheless large; for some vitamins, tissue concentrations various by greater than 10-20 p.c can imply critical unhealthy information.
Interactions amongst particular person vitamins in meals are substantial and dynamic—and have main sensible implications. An impressive overview by researchers Karen Kubena and David McMurray at Texas A&M College summarized the revealed results of a lot of vitamins on the exceptionally complicated immune system.[1] Nutrient pairs that have been discovered to affect one another and in flip, to affect elements of the immune system embrace vitamin E-selenium, vitamin E–vitamin C, vitamin E–vitamin A, and vitamin A–vitamin D. The mineral magnesium influences the consequences of iron, manganese, vitamin E, potassium, calcium, phosphorus, and sodium, and thru them the actions of a whole bunch of enzymes that course of them; copper interacts with iron, zinc, molybdenum, and selenium to have an effect on the immune system; dietary protein exerts completely different results on zinc; and vitamin A and dietary fats have an effect on one another’s means to affect the event of experimentally created most cancers.
Even carefully associated chemical substances throughout the similar chemical class can vastly affect one another. For instance, varied fatty acids have an effect on the immune system actions of different fatty acids. The impact of polyunsaturated fat (present in plant oils) on breast most cancers, for instance, is vastly modified by the quantity of complete and saturated fats within the weight loss plan.
The truth that magnesium has already been proven to be a vital a part of the operate of greater than 300 enzymes speaks volumes concerning the potentialities for the just about limitless nutrient interactions. The results of those interactions on drug-metabolizing enzymes and on the immune system additionally apply to different complicated methods, such because the hormonal, acid-base stability, and neurological methods.[2]
The proof cited right here represents solely an infinitesimally small fraction of the overall variety of interactions working each second in our our bodies. Clearly, the frequent perception that we are able to examine the consequences of a single nutrient or drug, unmindful of the potential modifications by different chemical elements, is foolhardy. This proof also needs to make us extraordinarily hesitant to “mega-dose” on vitamins remoted from entire meals. Our our bodies have advanced to eat entire meals, and may subsequently take care of the combos and interactions of vitamins contained in these meals. Give a physique 10,000 mg of vitamin C, nonetheless, and all bets are off.
Excerpt From
Complete: Rethinking the Science of Diet by T. Colin Campbell, PhD, with Howard Jacobson, PhD
© 2013 T. Colin Campbell
References
- Ok. S. Kubena and D. N. McMurray, “Diet and the Immune System: A Overview of Nutrient-Nutrient Interactions,” Journal of the American Dietetic Affiliation 96 (1996): 1156-1164.
- T. C. Campbell and J. R. Hayes, “Function of Diet within the Drug Metabolizing System,” Pharmacological Critiques 26 (1974): 171-197.
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