Plant dietary

Recognition among bone-chemistry researchers that strontium enters bone in proportion to dietary levels has resulted in widely accepted yet erroneous inferences about the relationships among various elements in bone and past diet. One such inference is that more of any element in the diet translates directly to more of that element in bone. If an element is not biogenically incorporated within bone, or if biological levels are metabolically controlled, then that element will not reflect diet. A second erroneous inference is that strontium can be used to measure the dietary plant/meat ratio. Sr/Ca ratios in meat are generally lower than those of plants, but meat is also low in calcium and hence has little effect on the composition of bone. Plants, on the other hand, contribute substantially to bone composition. Variations in the strontium levels of bone thus more likely reflect differential consumption of plants rather than trophic position. Although efforts to determine plant/meat ratios from strontium and to draw dietary inferences from elements other than strontium and barium have not been successful, this failure has been due to inappropriate expectations, not to a failure of bone strontium to reflect diet. 

Strontium, that of Toots and Voorhies (1965), used these compositional differences among plants to assess not the dietary plant/meat ratio but the degree of browsing versus grazing. It is this phenomenon due to shifting plants that we are likely to observe in comparative Sr/Ca studies of bone, rather than the amount of meat in the diet, simply because plants have a much greater impact on diet composition. 

Humans have not had time to evolve a toxic harmony with all of their dietary plants. The human diethas changed markedly in the last few thousand years. Indeed, very few of the plants that humans eat today, such as coffee, cocoa, tea, potatoes, tomatoes, corn, avocados, mangoes, olives, and kiwi fruit, would have been present in a hunter-gatherer s diet. Natural selection works far too slowly for humans to have evolved specific resistance to the food toxins in these newly introduced plants. 

Because they are necessary precursors for the synthesis of other products, linoleate and linolenate are essential fatty acids for mammals they must be obtained from dietary plant material. Once ingested, linoleate may be converted to certain other polyunsaturated acids, particularly y-linolenate, eicosatrienoate, and arachidonate (eicosatetraenoate), all of which can... 

Renal failure has a long history of treatment with protein-restricted diets. Dietary plant protein is a possible therapy mechanism for the treatment of chronic and acute renal failure. 

The cholesterol-lowering properties of dietary plant sterols have been known for decades (Best et al., 1954 Peterson, 1951 Poliak, 1953), due specifically to reductions in cholesterol absorption. Inverse correlations between plant sterol intake and cholesterol absorption have been reported in animals (Carr et al., 2002 Ntanios and Jones, 1999) and humans (Ellegard et al., 2000). The exact mechanism by which plant sterols inhibit cholesterol absorption is unclear, and several mechanisms of action have been proposed, including (1) competition with cholesterol for solubilization in micelles within the intestinal lumen, (2) cocrystallization with cholesterol to form insoluble crystals, (3) interaction with digestive enzymes, and (4) regulation of intestinal transporters of cholesterol. 

Andersson, S.W., Skinner, J., Ellegard, L., Welch, A.A., Bingham, S., Mulligan, A., Andersson, H., and Khaw, K.T. 2004. Intake of dietary plant sterols is inversely related to serum cholesterol concentration in men and women in the EPIC Norfolk population A cross-sectional study. Eur. 

Halvorsen BL, Holte K, Mari CW, et al. A systematic screening of total antioxidant in dietary plants. J Nutr 2002 132 461-471. 

Subbiah, M.T.R. 1971. Significance of dietary plants sterols in man and experimental animals. Mayo Clin. Proc. 46, 549-559. 

Miettinen, T.A. and Gylling, H., Regulation of cholesterol metabolism by dietary plant sterols, Curr. Opin. Lipidol, 10, 9, 1999. 

Endogenous Dietary Plant constituent Animal origin Synthetic... 

Anthocyanin glycosides with different colors are the daily dietary plant pigments they might prevent many diseases such as hypertension, diabetes, cardiac infarction, and eye insufficiency. The preventive and therapeutic properties of anthocyanins and flavonoids highly depend on absorption and metabolism in the living body after intake. 

Because the amount of dietary cholesterol is normally low, a substantial fraction of the cholesterol in the intestinal lumen comes from the biliary cholesterol secreted by the liver. ABCG5/8 also is expressed in the apical membrane of intestinal epithelial cells, where it helps control the amounts of cholesterol and plant-derived sterols absorbed apparently by pumping excess or unwanted absorbed sterols out of the epithelial cells back into the lumen (see Figure 18-11, step 5]). Partly as a result of this activity, only about 1 percent of dietary plant sterols, which are not metabolically useful to mammals, enter the bloodstream. Unabsorbed bile acids (normally <5 percent of the luminal bile acids) and unabsorbed cholesterol and plant sterols are eventually excreted in the feces. 

Although most hpids required for cell structure, fuel storage, or hormone synthesis can be synthesized from carbohydrates or proteins, we need a minimal level of certain dietary hpids for optimal health. These hpids, known as essential fatty acids, are required in our diet because we cannot synthesize fatty acids with these particular arrangements of double bonds. The essential fatty acids a-linoleic and a-linolenic acid are supphed by dietary plant oils, and eicosapentaenoic acid (ERA) and docosa-hexaenoic acid (DHA) are supplied in fish oils. They are the precursors of the eicosanoids (a set of hormone-like molecules that are secreted by cells in small quantities and have numerous important effects on neighboring cells). The eicosanoids include the prostaglandins, thromboxanes, leukotrienes, and other related compounds. 

Polyunsaturated fatty acids with double bonds three carbons from the methyl end (w3 fatty acids) and six carbons from the methyl end (w6 fatty acids) are required for the synthesis of eicosanoids (see Chapter 35). Because humans cannot synthesize these fatty acids de novo (i.e., from glucose via palmitate), they must be present in the diet or the diet must contain other fatty acids that can be converted to these fatty acids. We obtain w6 and w3 polyunsaturated fatty acids mainly from dietary plant oils that contain the w6 fatty acid linoleic acid (18 2, and the w3 fatty acid a-linolenic acid (18 3, In the body, linoleic acid can be converted by elongation and desatura-... 

Piironen, V., Toivo, J., and Lampi, A.M., Natural sources of dietary plant sterols, J. Food Comp. Anal, 13, 619, 2000. 

Nashed, B. et ah, Antiatherogenic effects of dietary plant sterols are associated with inhihition of pro-inflammatory cytokine production in Apo E-KO mice, J. Nutr, 135, 2438, 2005. 

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