From The March 2003 Issue of Functional Foods & Nutraceuticals
Yousry Naguib, PhD
Epidemiological studies have spurred heightened interest in carotenoids as dietary supplements. High intakes of certain fruits and vegetables rich in carotenoids may significantly reduce the risk of cardiovascular diseases, cancer and some aspects of ageing.
Carotenoids are a fat-soluble group of naturally occurring plant pigments. Fruits and vegetables get their vibrant colour from carotenoids. Approximately 600 carotenoids have been isolated from plants and animals. Of these, about 50 are present in a typical diet containing fruits and vegetables, and about 20 of them have been identified in our bodies.
Chemically, carotenoids can be divided into two main categories: carotenes and xanthophylls. Carotenes refer to carotenoids, which contain only carbon and hydrogen, such as beta-carotene, alpha-carotene and lycopene. Xanthophylls refer to compounds that contain an additional hydroxyl group (as with lutein, zeaxanthin and beta-cryptoxanthin), keto group (e.g., canthaxanthin) or both (e.g., astaxanthin).
Since humans cannot make carotenoids de novo, they depend upon the diet, exclusively, as the source of these important nutrients. Leafy green vegetables such as spinach and Brussels sprouts contain mostly lutein and zeaxanthin, while orange and yellow vegetables such as carrots, sweet potatoes and squash contain predominantly carotenes. Of all the carotenoids, alpha-carotene, beta-carotene and cryptoxanthin are the main vitamin A precursors.
Carotenoids are considered potential membrane antioxidants due to reactivity with singlet oxygen and oxygen free radicals. Singlet oxygen has been implicated in biological systems and is capable of damaging proteins, lipids and DNA and therefore is thought to be involved in the pathogenesis of numerous diseases. The anti-cancer activity of carotenoids may be, at least in part, attributable to its antioxidant activity insofar as oxygen radicals are related to the processes leading to human cancer.
People who eat a variety of antioxidant-rich foods are less likely to develop certain cancers than people whose diets lack antioxidants.  Increasing the intake of fruits and vegetables in an at-risk cancer population also increased serum carotenoids levels. A year-long randomised, controlled intervention study of men and women with a recent history of adenomas revealed that increasing intake of fruits and vegetables to at least eight servings per day increased by 11 per cent to 54 per cent plasma levels of these five carotenoids: alpha- and beta-carotene, beta-cryptoxanthin, lutein and zeaxanthin. 
In a study published in 1994, researchers found that men with high serum carotenoid levels had a coronary artery disease event rate 60 per cent less than those with the low carotenoid levels. 
Researchers studied the effect of increased fruit and vegetable intake on the plasma levels of lutein, lycopene, beta-carotene and vitamin E and susceptibility of low-density lipoprotein (LDL) to oxidation in smokers and non-smokers. Volunteers increased their intake of fruits and vegetables to provide 30mg/day of carotenoids for two weeks. The carotenoid levels increased 23 per cent in smokers and 11 per cent in nonsmokers, and the resistance of LDL to oxidation increased by 14 per cent in smokers and by 28 per cent in nonsmokers. The study suggested that carotenoids' inhibitory effect on LDL oxidation might be the underlying mechanism in their protective effect on cardiovascular disease. 
Lutein and Zeaxanthin
Lutein and zeaxanthin are found in egg yolks, marigold flowers and leafy green vegetables such as spinach, broccoli and winter squash. Lutein was first extracted from the corpus luteum, and hence its name.
These two carotenoids have demonstrated antioxidant abilities, and protect against macular degeneration and some cancers.
ANTIOXIDANT: Lutein and beta-carotene, carotenoids with and without provitamin-A activity, respectively, protected human liver cells against oxidant-induced damage, indicating that the antioxidant protective effect of these carotenoids is independent of provitamin-A activity. 
An in vitro experiment found both lutein and zeaxanthin were found to protect lipid membranes against UV radiation and oxygen free radical attack.  Another test-tube experiment showed lutein to be as effective as vitamin E in quenching singlet oxygen. 
MACULAR DEGENERATION: Lutein and zeaxanthin are the only carotenoids that have been identified in the macula, a yellow spot in the retina that provides the best visual acuity of the human eye. These carotenoids are referred to as macular pigment and are strongly implicated in maintaining eye health. They filter blue light from the retina and prevent oxidative stress or free radical-induced damage in the eye's macula. 
Observational studies have indicated that high intake of lutein and zeaxanthin from food is associated with a reduced risk of age-related macular degeneration, the leading cause of blindness in people over age 65. 
A small 2001 study in Spain found that lutein ester supplements containing 12mg/day all-trans-lutein and 3mg/day 13/15-ris-lutein and 3.3mg/day alpha-tocopherol increased the density of the macular pigment, and that 10 patients taking lutein ester supplements reported an average of 40 to 50 per cent improvement in visual acuity. Tolerance of glare was also improved significantly. 
CANCER PREVENTION: Researchers at the University of Utah Medical School examined the association of dietary alpha-carotene, beta-carotene, lycopene, lutein, zeaxanthin and beta-cryptoxanthin and the risk of colon cancer in more than 2,000 subjects. They found that lutein is inversely associated with colon cancer in both men and women, especially amongst those whose colon cancer was diagnosed when they were young and amongst those with tumours located in the proximal segment of the colon. The major dietary sources of lutein were spinach, broccoli, oranges and greens. 
A case-control study of diet and lung cancer in South Pacific populations showed an inverse association between lung cancer and lutein and vitamin E. Data from two prospective US studies (10 and 12 years follow-up periods) indicates an inverse but not significant association between dietary lutein intake and lung cancer. Carotenoid intakes were derived from the reported consumption of fruit and vegetables on food-frequency questionnaires administered at baseline and during follow-up.  Inverse associations were strongest after a four- to eight-year lag between dietary assessment and date of diagnosis.
|A carotenoid cocktail may seem to offer a greater spectrum of benefits, but single ingredients for targeted conditions are best|
A study on serum carotenoid levels in women in India with breast cancer of women showed lutein and zeaxanthin levels to be significantly lower than healthy controls in postmenopausal, but not pre-menopausal, women. 
BIOAVAILABILITY: The absorption of lutein in humans depends on the type of food, food ingredients such as fibres and fats, and on the type of processing. A study involving 69 volunteers showed that consumption of meals with vegetables such as broccoli, green peas and spinach (containing 1.7 to 24.6mg beta-carotene, 3.8 to 26mg lutein, 0.22 to 0.6mg folate, and 26 to 93mg vitamin C) for four days significantly increased plasma concentrations of lutein and vitamin C. Broccoli and green peas were richer sources of lutein. Disruption of the spinach matrix increased the plasma concentrations of lutein and folate, indicating that the bioavailability of lutein from spinach can be improved by cooking. 
In a study on six healthy young women, researchers found that some dietary fibres, such as pectin, guar, alginate, cellulose and wheat bran, significantly reduced the bioavailability of lutein, lycopene and beta-carotene by 40 to 75 per cent. 
The bioavailability of lutein also depends on the amount of fat in the diet. This was demonstrated in a study involving healthy volunteers who were divied into four groups. Each group received one of four different supplements: vitamin E (50mg), alpha- plus beta-carotene (8mg), lutein esters (8mg), or placebo for two weeks. The supplements were provided in a low- or high-fat spread. Plasma concentrations of all supplements in the supplemented group were higher than in the placebo group. The plasma lutein level was higher when lutein esters were consumed with the high-fat spread (207 per cent increase) than with the low-fat spread (88 per cent increase). The study concluded that optimal uptake of vitamin E and alpha- and beta-carotene requires a limited amount of fat whereas the amount of fat required for optimal intestinal uptake of lutein esters is higher. 
Another group of researchers compared the bioavailability of lutein esters with that of crystalline lutein in humans. Healthy volunteers were given high doses of either lutein or lutein esters, and researchers analysed their plasma for lutein, finding no statistically significant difference in plasma lutein between the two products. This study demonstrated that the bioavailability of lutein from lutein esters is the same as the bioavailability of lutein from purified crystalline lutein. 
Lycopene is most abundant in tomatoes (up to 10mg per tomato) and is responsible for its red colour. Lycopene is also present, in small amounts, in guava, rose hip, watermelon and grapefruit.
Lycopene is one of the major carotenoids in the diet of North Americans, and it appears to act as an antioxidant, protecting against prostate, cervical, breast, digestive tract and lung cancers. It may also help prevent atherosclerosis. 
Researchers in epidemiological studies have identified lycopene as the carotenoid with the clearest inverse relation to the development of prostate cancer.  Prostate cancer is the most common cancer in US men and the second leading cause of cancer deaths among men in all Western countries.
In a six-year study (1986-1992) of the dietary habits of 48,000 male healthcare professionals, researchers found that those eating 10 servings or more a week of cooked tomato products had prostate cancer risk one-third that of those eating less than two servings weekly. Pizza appeared to offer the most protection, suggesting lycopene may be better absorbed when cooked with fat. 
In another study, researchers found that women with the highest consumption of lycopene had one-third the risk of getting cervical cancer, compared with women who had low intakes. Eating one tomato a day appeared to reduce the risk. 
A case-controlled study involving 400 patients and 405 control subjects showed that intake of lycopene as well as vegetables, fruits, folate and vitamins C and E were inversely associated with breast-cancer risk.  The intake of vegetables, fruits and nutrients was estimated with a food frequency questionnaire on 64 food items, from which lycopene intake was estimated.
Another case-control study conducted between 1985 and 1991 in northern Italy showed that high intake of raw tomatoes is associated with a statistically significant reduction in the incidence of gastrointestinal tract cancer. 
In a 10- to 12-year follow-up of 47,000 men and 77,000 women, about 0.6 percent cases of lung cancer were diagnosed. Analysis of carotenoid intakes by food-frequency questionnaires revealed that alpha-carotene and lycopene intakes were significantly associated with a lower risk of lung cancer. In subjects who never smoked, a 63 per cent lower incidence of lung cancer was observed for the top compared with the bottom quintile of alpha-carotene intake. 
A case-controlled study, comprising 108 subjects with atherosclerosis, revealed a modest inverse relationship between serum lycopene and the risk of atherosclerosis, suggesting a protective role for lycopene against the development of atherosclerosis. 
Astaxanthin is best known for its commercial use in the aquaculture industry. Farmers use it in the feed to provide the pinkish-red color to salmon, trout and crustaceans such as crabs, krill and shrimp.
Astaxanthin is found in appreciable amounts in the yeast microorganisms Phaffia rhodozma and the microalgae Haematococcus pluvalis, which have recently gained considerable interest as potential sources of natural astaxanthin. Among the natural sources, H. pluvalis contains the highest level of astaxanthin, which exists mainly as esters of various fatty acids.
ANTIOXIDANT : Research studies have shown astaxanthin to be a powerful antioxidant that can enhance secondary immune responses in humans, and helps to reduce symptoms of H. pylori infections and carpal tunnel syndrome.
Astaxanthin is considered a potential membrane antioxidant due to its reactivity with singlet oxygen and oxygen free radicals. Astaxanthin attaches itself onto cell membranes and spans the cell membrane bilayer of fat, where free radical attack first occurs, and inhibits the destruction of fatty acids and proteins in cell and mitochondrial membranes caused by lipid peroxidation.
Studies showed the singlet oxygen-quenching ability of carotenoids, in descending order: astaxanthin, canthaxanthin, beta-carotene, zeaxanthin, lutein and vitamin E. 
In one test-tube study, astaxanthin was shown to display antioxidant activity greater than vitamin E and was referred to as 'super vitamin E.' 
However, in a recent in vitro experiment, astaxanthin showed an antioxidant activity similar to that of vitamin E, and twice that of alpha-carotene, lutein and lycopene.  This discrepancy might be due to different experimental conditions.
This antioxidant potency of astaxanthin is thought to be important in helping to reduce symptoms associated with rheumatoid arthritis (RA). A clinical study, presented at the meeting of the American College of Nutrition in Texas in October 2002, concluded that BioAstin (containing natural astaxanthin) might be an important addition to RA treatment, allowing patients to have less pain. In the eight-week, double-blind, placebo-controlled study, 14 patients with RA received a daily dose of three gel caps, each containing 4mg astaxanthin, and seven patients with RA received a placebo. Subjects completed a health assessment questionnaire at the beginning of the study and after four and eight weeks. The astaxanthin group showed a statistically significant improvement in symptoms of RA as compared to the placebo-group.
|The singlet oxygen-quenching ability of carotenoids, in descending order: astaxanthin, canthaxanthin, beta-carotene, zeaxanthin, lutein and vitamin E|
H. PYLORI: Astaxanthin's ability to provide protection against Helicobacter pylori (H. pylori), which in humans is associated with peptic ulcer disease and gastric carcinoma, was demonstrated in animal studies.
In one study, mice fed 40mcg/kg astaxanthin three weeks before tumour inoculation had significantly lower tumour size than controls. 
In another study, mice infected with H. pylori were given daily treatments for 10 days of either algal meal rich in astaxanthin of various potencies (10, 50 and 100 mg/kg body weight), 400 mg/kg vitamin C or control meals. After 1 and 10 days post-treatment, both the astaxanthin and vitamin C groups showed significantly lower H. pylori colonization levels and lower gastric inflammation. 
CARPAL TUNNEL: In a recent double-blind, placebo-controlled study, sponsored by Cyanotech (Kailua-Kona, Hawaii) and presented at the scientific meeting of the American College of Nutrition in San Antonio, Texas, in October 2002, astaxanthin was shown to improve the condition of patients with carpal tunnel syndrome. Patients who took three gel caps, each containing 4mg of astaxanthin, for eight weeks reported a reduction in both the severity and duration of wrist pain as compared to the control group. 
Beta-carotene is the most well known of the carotenoids and the predominant one in carrots, sweet potatoes and broccoli. Beta-carotene from vegetables and fruits is associated with reduced risks of breast, stomach, esophageal and pancreatic cancers. People who eat a variety of vegetables and fruits containing carotenoids, including beta-carotene, are less likely to develop certain cancers than people whose diets lack these nutrients. 
In contrast to epidemiological studies, which showed lower risk of cancer among individuals eating fruits and vegetables rich in carotenoids, clinical trials indicate that beta-carotene supplements increase the incidence of lung cancer in cigarette smokers. This effect has been attributed to pro-oxidant action under the considerable oxidative stress of smokers. These clinical trials involved male heavy smokers (ATBC trial, alpha-tocopherol beta-carotene), male asbestos workers and male and female smokers (CARET, beta-carotene and retinal efficacy trial), and US male physicians' study (included 11 per cent smokers). All three trials concluded that beta-carotene provided no protection against lung cancer; two trials found a higher risk for lung cancer for those subjects given beta-carotene. 
In another study, researchers at the Johns Hopkins University School of Medicine found that smokers with the lowest blood levels of beta-carotene had about three-and-half times the risk of heart attack of people who had high levels of beta-carotene and did not smoke. 
A recent telephone interview study of postmenopausal women's diets throughout their lifetimes, with 273 incident cases of breast cancer and 371 controls, revealed that women were at lower risk of breast cancer with increasing levels of reported intake of beta-carotene. 
Beta-cryptoxanthin is another major source of vitamin A, often second only to beta-carotene. It is present in fruits such as oranges, tangerines and papayas. The contents ranged from 8mcg per 100g beta-cryptoxanthin laurate in Tunisian orange to 892 mcg per 100g beta-cryptoxanthin laurate in papaya. 
The anticarcinogenic activity of beta-cryptoxanthin was demonstrated in an animal study. Rats received methyl nitroso-urea, to induce colon cancer, and either a diet with cryptoxanthin or a diet without cryptoxanthin. At week 30, the colon cancer incidence was significantly lower in the cryptoxanthin-group, suggesting a protective effect of cryptoxanthin against colon cancer. 
The association between dietary vitamin and carotenoid intake and bladder cancer incidence was examined in a diet study on more than 120,000 subjects aged 55 to 69 years. After six years follow-up, the study found that only beta-cryptoxanthin intake appeared to be inversely associated with bladder-cancer risk. 
In addition to their role as a source of vitamin A, beta-carotene and beta-cryptoxanthin play an important role in human health; and as antioxidants they protect biological cells and tissues from the damaging effects of free radicals and singlet oxygen.
Making a household name
Research studies show carotenoids scavenge free radicals that play a major role in the onset and advancement of many common diseases. They inhibit lipid peroxidation, enhance eye health and immune systems and reduce the risk of certain cancers.
Although it is tempting to formulate a cocktail of carotenoids with the desire to provide a full spectrum of health benefits, it is advised to take into consideration the health benefit to be targeted. For example, it might not beneficial to include lycopene for an eye health formula because this carotenoid has no demonstrated efficacy for improved vision. The take-home message is, research shows many benefits inherent in carotenoids. A careful look at the literature will point suppliers and manufacturers in the optimal direction.
Yousry Naguib, PhD, is a manager of new products development at Los Angeles-based Soft Gel Technologies. He is an author and former professor at Suez Canal University in Egypt.
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Marketing applications: condition-specific carotenoids
Why are we so preoccupied with vegetables? Consumers don't want to eat them, but every expert or public health commentator tells us to eat more. Why? Perhaps because epidemiological research shows how beneficial they are. Still, consumers do not routinely eat home-cooked or home-heated vegetables.
From a marketing point of view, messages related to or based on epidemiological research is like a guilt message from mum—'eat your vegetables.' Further, the value of words like 'carotenoids' (and to a lesser extent, 'antioxidants') is difficult to measure in consumers. How can it be when antioxidant—or substitute carotenoid—is linked to all types of diseases?
Just such a scenario may be the reason that carotenoids as a category may have a hard time growing significantly. How to fix? Enter the concepts of condition-specific or, even more to the point, preparation-specific marketing.
How might this be executed? Certain carotenoid combinations, as pointed out in the accompanying literature review, may have specific health benefits. Certainly eye health has boosted the fate of lutein and perhaps now zeaxanthin. The leading ingredient in this area is itself a specific preparation and should continue to see sales growth based on specfic research demonstrating its usefulness for prevention and treatment of ocular diseases.
The same could be positioned within the specific area of sun protection. Recent research published in the January 2003 issue of Journal of Nutrition shows that carotenoids taken orally in a blend or singly as beta-carotene can have a sun-protective effect for the skin in humans. This may establish a specific consumer benefit that a blend or dominant carotenoid can tap into.
Combining a specific consumer application with a specific preparation and demonstrating by controlled clincal evidence that it has value to the consumer is the way to build a strong conglomerate carotenoid market. The end result is a reward to ingredient suppliers and finished good marketers for their efforts.
Intellectual property: carotenoids with punch
Carotenoids, as well as providing the characteristic colouring associated with many common fruits and vegetables, function as powerful antioxidants and immunopotentiators. Diets rich in carotenoids are linked with a decreased risk of many serious disorders, including heart disease, cancer and degenerative eye disease. JUDY DAVIS looks at recent innovations
A patent from Israel-based Lycored Natural Products describes a further carotenoid-based product for use in the battle against heart disease. This time, the product is aimed at inhibiting LDL oxidation and thus arresting the progression of atherosclerosis. According to the patent, the carotenoids phytoene and phytofluene are more effective in inhibiting LDL oxidation than other carotenoids such as lycopene, although their effectiveness in such applications has not previously been evaluated.
The product consists of a therapeutically effective amount of phytoene, phytofluene or a combination of the two, and can be formulated as a supplement or in functional foods or drinks. (PCT Patent Application WO 02/058682)
Novel carotenoid esters
Esters are formed by the reaction of an acid with an alcohol and are the organic equivalent of inorganic salts. Esters with a carotenoid as the alcohol-derived moiety are well known; for example, monoesters and diesters of lutein and zeaxanthin with palmitic, myristic and stearic acids occur naturally and are known as the xanthophylls. Esters containing a carotenoid as the acid-derived moiety also occur in nature.
Researchers working at Barlovento International now claim to have developed an entirely new class of carotenoid ester in which both the alcohol-derived moiety and the acid-derived moiety are carotenoids—in effect, delivering a double dose of carotenoid in one molecule. They are prepared by the esterification of a combination of at least one hydroxy carotenoid, such as lutein or zeaxanthin, with at least one carboxylic carotenoid, such as bixin, norbixin or beta-apo-8'-carotenoic acid.
According to the patent, the new class of "all-carotenoid esters" shows the combined colour characteristics of both carotenoid fractions and have high antioxidant potential and outstanding fat solubility. (PCT Patent Application WO 02/068385)
Protection against heart disease is one of the many health benefits associated with consumption of carotenoid-rich diets, and it is along this line that Lycored Natural Products Industries has filed a patent for use of specific carotenoids for lowering blood pressure. The patented compositions contain a carotenoid selected from the group consisting of lycopene, phytofluene, phytoene, astaxanthin and canthaxanthin or their mixtures. According to the patent, administration of these carotenoids in a therapeutically effective amount can bring about a relatively fast response in the reduction of blood pressure by improving the physical properties of blood (lowering viscosity) and altering the physical/mechanical properties of blood vessels (increasing flexibility).
The compositions, in the form of supplements or included in functional foods, are said to offer a natural treatment that avoids undesirable side effects associated with use of conventional anti-hypertensive agents. (PCT Patent Application WO 02/058683)
One of the major challenges when formulating carotenoids is overcoming their lack of solubility and homogeneous dispersibility in water. This is caused partly by their high lipophilicity and partly by their rigid structure—both of which are factors that can lead to poor in vivo bioavailability.
Researchers working for Jerusalem-based Yissum Research & Development claim to have resolved the problem by developing new encapsulated formulations in which the water-immiscible carotenoids are enclosed in liposomes. This is achieved by forming a suspension of a carotenoid in a mixture of liposome-forming lipids and organic solvent and then drying the resulting product. The method is particularly suitable for highly lipophilic, rigidly structured carotenoids such as lycopene, and phospholipids are the preferred liposome-forming lipids.
The resulting liposomal formulations can be used in functional foods to protect the body against damage caused by systemic oxidants, or applied topically for the treatment or prevention of skin damage caused, for example, by UV light. (PCT Patent Application WO 02/064110)
This information has been complied by UK-based Leatherhead Food International.
For further information, contact Judy Davis.
Tel: +44 1372 822241
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