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The term phytochemical refers to a classification system of botanical
chemicals. Broadly stated phytochemicals are chemicals that plants
produce to perform metabolic functions, as for example, wood creating
cellulose, sugar cane manufacturing sucrose, and opium poppies producing
morphine. 1
Phyonutrient, within the context of natural health and nutrition, has
come to refer to bio- active plant chemicals that humans eat and have or
may well have significant positive effects on human metabolism.
Phtyochemicals that are concentrated or prepared in such a dosage as to
have likely therapeutic effects are generally becoming referred to as
nutraceuticals.
Phytonutrients are not essential for life, but they appear to be
essential for optimal health and longevity. They therefore may properly
be classed as micro-nutrients, along with vitamins and minerals. The
technical classification includes: terpenes, amines, organosulfurs,
phenols, polysaccarides, organic acids, and lipids. One food can contain
several classifications of phytonutrients. For example, an orange
contains terpines (carotenoids and limonoids) and phenols (bioflavinoids).
In this three part introductory article, we will briefly examine some of
the major sub-groups of phytonutrients and how they may contribute
towards optimal function.
Phytosterols: Inhibition of Cholesterol Absorption; Modulation of
Hormone Metabolism, Immune Function, and Inflammatory Physiology
Phytosterols, saponins, phenolics, pectins and soluble fibers are
sub-classifications of phytonutrients known particularly for their
cholesterol lowering abilities. Examples from each subgroup include
flax, pumpkin and sesame seed (phytosterols), fenugreek and ginseng (saponins),
cherries and green tea (phenolics), apples and prunes (pectins), and oat
beta glucan and rice bran (soluble fibers). Phytosterols are lipids,
saponins are terpines, phenolics are phenols, and pectins and soluble
fibers are polysaccarides.
Nuts are the richest source of phytosterols in the Western diet.
Numerous studies demonstrate that diets rich in nuts and seeds are
associated with a decreased occurrence of cardio-vascular disease (CVD).
2
Cold-pressed unrefined vegetable oils such as flaxseed, hazelnut, olive,
sesame, wheat germ, and walnut are excellent sources of phytosterols.
Refining and hydrogenation drastically reduces phytosterol
concentrations by 40-85 %. 3
Phytosterols are poorly absorbed. They lower cholesterol by interfering
with its absorption in the small intestine. Three grams of phytosterols
daily show significant lipid lowering effects. 4
Algae and fungi also manufacture phytosterols. For example, as presented
at the American Heart Association's 39th Annual conference in 1999,
ergosterol from red yeast grown on rice has lipid lowering effects
similar to statins. Various mushrooms, seaweeds, and spirulina contain
many sterols, including fuctosterol, sitosterol, ergosterol.
Phytosterols can also mimic hormone precursors or modulate hormones
themselves. For example, Swedish tree pollen, pumpkin seeds, pygeum, and
saw palmetto are all used in cases of benign hyper-trophic prostate
disease (BHP) and prostatitis. These phytosterols inhibit the
conversion of testosterone to dehydroxytestoterone (DHT). 5
Phytosterol steroid mimicry also contributes to the anti-inflammatory
effects of cold processed oils, as from flaxseeds and olives. The EFA
lipids help modulate eicosinoid production, the omega-6 EFA’s being
precursors to prostaglandin E1, and the omega 3 EFA’s serving as
precursors for prostaglandin E3, both anti-inflammatory in action 6
Specially prepared and concentrated phytosterols (sterols and sterolins)
from sesame seed are used to modulate immune function through thymus
hormones (T1 and T2) and interleukins, while modulating DHEA/Cortisol
balance as well.7
The Carotenoids: Powerful Antioxidants for Cancer Prevention, Optimizing
Cardio-Vascular Dynamics, Protecting Vision
Carotenoids, a fat soluble group of naturally occurring plant pigments,
are a sub-classification of the terpenes. Perhaps the most familiar of
phytonutrients, carotenoids function as powerful antioxidants and
immuno-potentiaters. Diets rich in carotenoids are linked with a
decreased risk of heart disease, cancer, and degenerative eye diseases
like macular degeneration and cataracts. 8
There are approximately 600 known carotenoids, 50 of which are present
in our diets, mostly from fruits and vegetables. Twenty have been
identified in the human body. 9
Chemically, carotenoids are classified in two main groups: carotenes and
xanophylls. Carotenes refer to the carotenoids that contain only carbon
and hydrogen (beta-carotene and lycopene). Xanthophylls refer to
compounds that contain in addition a hydroxyl group (lutein, zeaxanthin,
and beta-cryptoxanthin), a keto group (canthaxanthin) or both (astaxanthin).
Alpha- carotene, beta-carotene, and cryptoxanthin are the main vitamin A
precursors.
Carotenoids are considered potent membrane antioxidants due to their
reactivity with singlet oxygen. Ranked by antioxidant power we can list
astaxanthin, canthaxanthin, beta-carotene, zeaxanthin, and lutein as all
stronger than vitamin E!
Leafy green vegetables contain mostly lutein and zeaxanthin. Carrots,
oranges, sweet potatoes and squash contain mainly carotenes.
Interestingly, the yellow yolk of eggs is rich in lutein, and the
astaxanthin group from red algae is what makes salmon pink.
Lutein and zeaxanthin are the only carotenoids identified in the macula.
There they filter blue light from the retina and inhibit oxidative
damage. Such damage leads to macular degeneration, the leading cause of
blindness in those over 65.
Researchers at the University of Utah Medical School found that lutein
intake is inversely associated with colon cancer. 10 A study on serum
carotenoid levels in women in India with breast cancer showed lutein and
zeaxanthin to be significantly lower than in healthy controls, at least
in postmenopausal women.11
Lycopene is most abundant in tomatoes with smaller amounts in pink
grapefruit, watermelon, guava, and rose hips. Lycopene makes up
approximately 50% of the total carotenoids in blood plasma of those
persons consuming Western diets. It protects against prostate, cervical,
breast, digestive tract and lung cancers, and perhaps atherosclerosis.
12
Zeta carotene, phytoene and phytofluene are also found in tomatoes and
are sometimes referred to as “the three amigos”! The latter two,
according to a patent by Lycored Natural Products, are more effective in
inhibiting LDL oxidation than other carotenoids. They have also filed a
patent for a blood pressure lowering combination of lycopene,
phytofluene, phytoene, astaxanthin and canthaxanthin. The patent claims
that administration of these carotenoids in therapeutic dosages can
rapidly lower blood pressure by lowering blood viscosity and increasing
vessel flexibility.
Astaxanthin, found mostly in red yeasts and red algae, is now fed to
salmon, trout, crabs, krill and shrimp in “fish farms” to provide the
red and pink color of their natural red algae eating wild brethren. This
most powerful of the carotenoid antioxidants has been shown to enhance
secondary immune response in humans, and help reduce symptoms of H.
pylori, CTS and RA. 13
Beta- carotene intake is associated with reduced risk of breast,
stomach, esophageal, and pancreatic cancers. 14 Researchers at John
Hopkins reported in 1994 that smokers with the lowest blood levels of
beta-carotene had approximately a 350% greater risk of heart attack as
compared to non-smokers with high beta carotene levels.
Beta-cryptoxanthin, found mostly in fruits like oranges, tangerine and
papayas, is second only to beta carotene as a source of vitamin A.
Cryptoxanthin, again demonstrating the uniqueness of each phytonutrient,
is the only carotenoid that appears to be related inversely to bladder
cancer risk. 15
Of note, some carotenoids rich foods like carrots and tomatoes yield
more beta-carotene and lycopene, respectively, when cooked. Lutein and
lycopene require fat for optimal uptake of carotenoids whereas dietary
fiber inhibits its absorption of lutein, lycopene, and beta-carotene by
40% to 75 % 16, 17
End Part 1 of III
1.) Broadhurst, C.L., PH. D., Nutrition Science News, July 2001, Vol.
6, No. 7, p 262
2.) (Sebate J, et al. Nut consumption and coronary heart disease
risk. Handbook of Lipids in Human Nutrtion. Boca Raton (FL): CRC Press
1996. p145-51
3.) Farquar JW. Plant Sterols:their biologocial effects in humans.
Handbook of Lipids in Human Nutrtion. Boca Raton (FL): CRC Press 1996.
p101-5
4.) Jones PJ, Raieini-Sarjaz M. Plant sterols and their derivatives:
the current spread of results. Nutr. Rev. 2001:59:21-4
5.) Buck AC, Phytotherapy for the prostate. Br. J Urol. 1996:78:325-6
6.) Mayes, P.A. Metabolism of unsaturated fatty acids & eicosanoids.
In: Harper's Biochemistry 23rd ed. Appleton & Lange, Norwalk, CT, 1993.
7.) Vanderhaeghe, L. Healthy Immunity, Issue 8, p. 1-3
8.) Functional Foods and Nutraceuticals, March 2003, p. 64.
9.) Ibid, p 58.
10.) Slattery ML, et.al. Carotenoids and colon cancer. Am.J. Clin.
Nutr. 2000 Feb: 71 (2): 575-82
11.) Ito Y., et al. A study of serum carotenoids levels in breast
cancer in Indian women in Chenni, India. J Epidemiol 1999 Nov: 9(5):
306-14
12.) Agarwal S, Rao AV. Carotinoids and chronic diseases. Drug Metab
Drug Interact 2000:17(1-4):189-210)
13.) Naguib, Y. Carotenoids come of age. Functional Foods and
Nutraceuticals, Mar. 2003, p. 68
14.) Nishino H et al. Cancer prevention by carotenoids. Biofactors
2000:13:89
15.) Zeegers, MP. Are retinol,vitamin C, vitamin E, folate and
carotenoids intake associated with bladder cancer risk? Results from the
Netherlands Cohort Study. Br. J Cancer 2001 Sep 28:85(7): 977-83
16.) Reidl, J. et al. Some dietary fibers reduce absorption of
carotenoids in women. J Nutr 1999 Dec: 129 (12): 2170-6
17.) Roodberg AJ, et al. Amount of fat in the diet affects lutein
esters but not of alpha carotene, beta carotene, and vitamin E in
humans. Am J Clin Nutr 2000 May; 71(5):1187-93
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