Some claim that soy-based meal-replacement formulas are ineffective for weight loss. However, the fact is that soy protein has been used effectively as a component of weight loss diets for more than 20 years. Animal studies have shown that soy protein and its associated bioactive isoflavones and peptides can have beneficial effects on glucose metabolism, fat metabolism, insulin sensitivity, metabolic rate, food intake and weight loss. Studies in humans have further shown that increased intakes of soy or animal protein can increase metabolic rate, decrease appetite, and increase satiety. Furthermore, randomized clinical trials and clinical weight loss studies have shown that diets based on soy protein are every bit as effective - if not more effective - than diets based on dairy protein when it comes to helping people lose weight and abdominal fat.
The truth is that weight loss is much more a function of reducing caloric intake and increasing calories burned through exercise, as opposed to simply using soy or whey protein in the diet.
The Nutritional Value of Soy Protein
Several scales for assessing the nutritional value of protein have been developed over the years. These have been used to rate various proteins for their ability to support growth, supply important amino acids, and generally satisfy the human protein requirement. The first broadly accepted standard was the Protein Effectiveness Ratio (PER). Developed in 1919, this method focused on the growth-supporting characteristics of a given protein, and it used rats (rather than humans) as the test animal. Because of the metabolic differences between rodents and humans, this method has been largely discredited and is rarely used today.
A second method, the Biological Value (BV) scale, is based on the retention of protein nitrogen by the body. It is thought to be a good measure of protein utilization. The BV scale stretches from 0 to 100, with a score of 100 indicating that virtually 100% of a given protein's nitrogen is retained by the body. Some people - particularly in the sports world - use this method, but it is not widely accepted within the community of nutritional scientists.
Most nutritionists (and many in the sports sector) now consider the Protein Digestibility Corrected Amino Acid Score (PDCAAS) to be the international standard for assessing protein quality. This approach, developed by the Food and Agriculture Organization and endorsed by the U.S. Food and Drug Administration, considers the amino acid balance of a given protein as it compares with the amino acid needs of humans, with specific reference to 2-5 year old children. It also takes into account the digestibility of the protein, or how fully the protein is broken down and absorbed by the body. The PDCAAS scale stretches from 0.0 to 1.0, with a score of 1.0 indicating that the protein completely satisfies human needs from a quality perspective.
During the 1990’s, whey protein became the protein of choice among bodybuilders, due in large part to an intense and successful marketing campaign sponsored by the dairy industry. That marketing promotion was based on the fact that some whey protein isolates have a rating of 100 on the BV scale. In comparison, egg-white protein (the traditional standard for bodybuilders) typically ranks in the 90’s, while most fish, beef, and soy proteins rank in the 70’s on the BV scale. (You will see a wide variety of BV scores for these foods because different people express the ratios in different ways, and the techniques for measuring BV are imprecise and not easily replicated from one experiment to another.)
However, when the PDCAAS approach is employed, soy protein isolates, whey protein isolates, and egg white protein all score a complete 1.00, meaning they all exhibit very high - and essentially equivalent - nutritional value in supporting human health.
The high PDCAAS score for soy protein isolates speaks to two important points. First, soy protein is well-digested and absorbed by humans. (This is the “D” of PDCAAS). Second, soy protein is complete. It contains all the essential amino acids in a proper balance for human growth, development, and health. (This is the “AA” of PDCAAS.)
Some authors have claimed that soy is lacking in the essential amino acid methionine, as if to imply that soy contains no methionine. This is incorrect. Soy may not be rich in methionine, but it contains enough to supply human needs under most circumstances. Furthermore, it is important to point out that human methionine requirements can be partially met by another sulfur-containing amino acid (cysteine). When cysteine + methionine content is considered, soy protein is nutritionally excellent.
A second method, the Biological Value (BV) scale, is based on the retention of protein nitrogen by the body. It is thought to be a good measure of protein utilization. The BV scale stretches from 0 to 100, with a score of 100 indicating that virtually 100% of a given protein's nitrogen is retained by the body. Some people - particularly in the sports world - use this method, but it is not widely accepted within the community of nutritional scientists.
Most nutritionists (and many in the sports sector) now consider the Protein Digestibility Corrected Amino Acid Score (PDCAAS) to be the international standard for assessing protein quality. This approach, developed by the Food and Agriculture Organization and endorsed by the U.S. Food and Drug Administration, considers the amino acid balance of a given protein as it compares with the amino acid needs of humans, with specific reference to 2-5 year old children. It also takes into account the digestibility of the protein, or how fully the protein is broken down and absorbed by the body. The PDCAAS scale stretches from 0.0 to 1.0, with a score of 1.0 indicating that the protein completely satisfies human needs from a quality perspective.
During the 1990’s, whey protein became the protein of choice among bodybuilders, due in large part to an intense and successful marketing campaign sponsored by the dairy industry. That marketing promotion was based on the fact that some whey protein isolates have a rating of 100 on the BV scale. In comparison, egg-white protein (the traditional standard for bodybuilders) typically ranks in the 90’s, while most fish, beef, and soy proteins rank in the 70’s on the BV scale. (You will see a wide variety of BV scores for these foods because different people express the ratios in different ways, and the techniques for measuring BV are imprecise and not easily replicated from one experiment to another.)
However, when the PDCAAS approach is employed, soy protein isolates, whey protein isolates, and egg white protein all score a complete 1.00, meaning they all exhibit very high - and essentially equivalent - nutritional value in supporting human health.
The high PDCAAS score for soy protein isolates speaks to two important points. First, soy protein is well-digested and absorbed by humans. (This is the “D” of PDCAAS). Second, soy protein is complete. It contains all the essential amino acids in a proper balance for human growth, development, and health. (This is the “AA” of PDCAAS.)
Some authors have claimed that soy is lacking in the essential amino acid methionine, as if to imply that soy contains no methionine. This is incorrect. Soy may not be rich in methionine, but it contains enough to supply human needs under most circumstances. Furthermore, it is important to point out that human methionine requirements can be partially met by another sulfur-containing amino acid (cysteine). When cysteine + methionine content is considered, soy protein is nutritionally excellent.
Soy Allergies and Sensitivities
Soy is on the Food and Agriculture Organization’s list of the eight most prevalent food allergens. This list includes milk, eggs, fish, crustacea, wheat, peanuts, tree nuts, and soy. Together, these foods account for about 90% of food allergies.
That said, it is important to understand that these high-profile food allergies differ widely in their incidence, severity, and symptoms, and that soy protein - relative to milk and nut proteins, for example - is a relatively mild allergen. Consider the following:
Beyond true allergic reactions, some people may be sensitive to the “non-digestible” sugars and fiber in soy. These components can cause abdominal bloating and gas, just like the sugars and fibers in most beans and just like the lactose in milk. Such symptoms are generally reduced, if not eliminated, when people use highly refined soy protein isolates which are 90-92% soy protein and only 3-4% carbohydrate (fiber plus simple and complex sugars and starches).
That said, it is important to understand that these high-profile food allergies differ widely in their incidence, severity, and symptoms, and that soy protein - relative to milk and nut proteins, for example - is a relatively mild allergen. Consider the following:
- Milk and peanut allergies are each 5-6 times more prevalent than soy allergies. In fact, the true incidence of soy allergy - as confirmed by double blind, placebo-controlled food challenges - is quite low. Research indicates that allergic reactions to soy occur predominately in children less than four years of age, and most estimates agree that <1.0% of children (probably 0.2-0.4% of children) have true soy allergies. Moreover, 90% of children who have reactions to soy outgrow the allergy by age four. Given these statistics, it is safe to assume that <0.1% of adults (fewer than 1 in 1,000) are allergic to soy.
- Food allergen reaction thresholds, or the minimum oral dose of protein that elicits an allergic response, tend to be several orders of magnitude (more than 100-1000 times) higher for soy than for milk and peanut proteins. In other words, it takes 100-1000 times more soy protein than milk or peanut protein to initiate an allergic response in sensitive people.
- Soy allergies tend to produce mild symptoms relative to other food allergies. In a summary report of clinical food challenge studies, it was noted that in 80% of reported cases, symptoms of soy allergies were minimal to mild, with the remaining 20% being moderate. No severe allergic reactions to soy were reported. In comparison, milk and peanut allergies produced minimal-to-mild symptoms in 50-70% of cases, moderate symptoms in 20-30% of cases, and severe symptoms in 10-15% of cases.
Beyond true allergic reactions, some people may be sensitive to the “non-digestible” sugars and fiber in soy. These components can cause abdominal bloating and gas, just like the sugars and fibers in most beans and just like the lactose in milk. Such symptoms are generally reduced, if not eliminated, when people use highly refined soy protein isolates which are 90-92% soy protein and only 3-4% carbohydrate (fiber plus simple and complex sugars and starches).
Alpha Lipoic Acid
Alpha lipoic acid (ALA), also known as lipoic acid (LA) or thioctic acid, is a vitamin-like antioxidant. Some refer to ALA as the "universal antioxidant" because it has the unique attribute of being both fat and water-soluble. Another unique aspect of ALA is its ability to regenerate other antioxidants back to active states, including vitamin C, vitamin E, glutathione, and Coenzyme Q10.
Several experimental and clinical studies have shown potential therapeutic uses for alpha lipoic acid in addressing diabetes, atherosclerosis, cataracts, heavy metal poisoning, neurodegenerative diseases, and HIV infection.
Alpha lipoic acid is produced naturally by most organisms, including humans. It is also present in many foods, with above-average amounts in organ meats (kidney, heart, liver), potatoes, spinach, and broccoli. Unfortunately, total dietary availability of ALA is quite poor. One of the first groups of researchers to isolate alpha-lipoic acid required nearly 10 tons of liver residue to produce a mere 30mg of crystalline LA. Because of this, all supplemental ALA is produced synthetically.
Currently no RDI value has been set, nor has the issue been adequately studied. Some researchers believe that the amount needed for therapeutic antioxidant activity exceeds that produced by our bodies or consumed in a normal diet. As such, alpha lipoic acid is a strong candidate for dietary supplementation. Maintenance doses of 10-25 mg per day have been suggested, while doses up to several hundred milligrams per day have been used therapeutically.
Several experimental and clinical studies have shown potential therapeutic uses for alpha lipoic acid in addressing diabetes, atherosclerosis, cataracts, heavy metal poisoning, neurodegenerative diseases, and HIV infection.
Alpha lipoic acid is produced naturally by most organisms, including humans. It is also present in many foods, with above-average amounts in organ meats (kidney, heart, liver), potatoes, spinach, and broccoli. Unfortunately, total dietary availability of ALA is quite poor. One of the first groups of researchers to isolate alpha-lipoic acid required nearly 10 tons of liver residue to produce a mere 30mg of crystalline LA. Because of this, all supplemental ALA is produced synthetically.
Currently no RDI value has been set, nor has the issue been adequately studied. Some researchers believe that the amount needed for therapeutic antioxidant activity exceeds that produced by our bodies or consumed in a normal diet. As such, alpha lipoic acid is a strong candidate for dietary supplementation. Maintenance doses of 10-25 mg per day have been suggested, while doses up to several hundred milligrams per day have been used therapeutically.
Vitamin C (Mineral Ascorbates)
Vitamin C, also known as ascorbic acid or ascorbate, plays two important roles in the body. First, it is a cofactor or cosubstrate for eight enzyme systems involved in various functions, including collagen synthesis, ATP synthesis in mitochondria, and hormone biosynthesis. Second, vitamin C is a powerful water-soluble antioxidant with a vital role in protecting cells and tissues from damaging oxidizing agents, including superoxides, hydroxyl radicals, and other free radicals. All these functions derive from one fundamental property: vitamin C is a powerful reducing agent (or electron donor) capable of neutralizing reactive oxidants.
Related functions performed by vitamin C include regenerating vitamin E to its active state, promoting iron absorption in the intestines by keeping iron in its reduced form, and participation in DNA transcription and protein synthesis regulation.
The richest dietary sources of vitamin C include cantaloupe, grapefruit, honeydew, kiwi, mango, oranges and other citrus fruits, strawberries, and watermelon. The richest vegetable sources include asparagus, broccoli, brussels sprouts, dark green leafy vegetables, and peppers.
Although vitamin C is generally non-toxic, very high dosages (several grams or more) may cause or contribute to gastrointestinal distress and diarrhea.
Additional Resources:
Related functions performed by vitamin C include regenerating vitamin E to its active state, promoting iron absorption in the intestines by keeping iron in its reduced form, and participation in DNA transcription and protein synthesis regulation.
The richest dietary sources of vitamin C include cantaloupe, grapefruit, honeydew, kiwi, mango, oranges and other citrus fruits, strawberries, and watermelon. The richest vegetable sources include asparagus, broccoli, brussels sprouts, dark green leafy vegetables, and peppers.
Although vitamin C is generally non-toxic, very high dosages (several grams or more) may cause or contribute to gastrointestinal distress and diarrhea.
Additional Resources:
- Vitamin C - U.S. National Library of Medicine
- Vitamin C - Physicians' Desktop Reference
- Vitamin C - Mayo Clinic
- Vitamin C - Linus Pauling Institute
- Vitamin C - Wikipedia
What is Elemental Calcium
Due to its high reactivity, calcium is rarely found in its elemental (or pure) state in nature. Similarly, you cannot buy pure calcium; it is always combined with another element to make it less reactive. During digestion, your body breaks the combination of calcium and other elements apart to make the calcium available for absorption.
What this means is that a 500 mg calcium supplement tablet may not be 500 mg of calcium, but a 500 mg mixture of calcium and other elements. The actual amount of usable calcium in a supplement is called elemental calcium.
Check out this hub: Do Calcium Supplements Cause Kidney Stones and Constipation for more information about Calcium
What this means is that a 500 mg calcium supplement tablet may not be 500 mg of calcium, but a 500 mg mixture of calcium and other elements. The actual amount of usable calcium in a supplement is called elemental calcium.
Check out this hub: Do Calcium Supplements Cause Kidney Stones and Constipation for more information about Calcium
Beta-Carotene & Vitamin A
Carotenoids comprise a diverse class of antioxidant molecules that help protect the body from oxidative damage. Approximately 700 natural carotenoids have been isolated and characterized. Most are derived from plants, where they serve multiple functions: photosynthetic pigments, photoprotectants, and free radical scavengers. Some 50-60 carotenoids are present in a typical diet with the major sources being fruits and vegetables.
Beta-carotene is one of the best known carotenoids, likely because: (1) it is one of the most abundant in a typical adult diet, and (2) it provides two nutritional functions - in addition to its role as an antioxidant, the human body converts beta-carotene into vitamin A.
Other members of the antioxidant carotenoid family include alpha-carotene, cryptoxanthin, zeaxanthin, lutein, and lycopene. Unlike beta-carotene, most of these nutrients are not converted to vitamin A in significant amounts.
Beta carotene's role as an antioxidant is based on its extensive system of conjugated double bonds which, upon reacting with an oxygen atom, absorb and diffuse that oxygen's potentially destructive energy. The oxygen atom returns to a lower energy state, and beta carotene dissipates the absorbed energy harmlessly (as heat). Similar mechanisms are involved in quenching the oxidative potential of hydroxyl radicals and other free radical compounds.
As provitamin A, beta carotene contributes to an entirely different set of functions by supplying a portion of the body's requirement for retinol (vitamin A). In fact, a single molecule of beta-carotene can be cleaved in the body to produce two molecules of vitamin A. Other carotenoids (including alpha-carotene, gamma-carotene, and cryptoxanthin) provide provitamin A activity, but yield only one molecule of vitamin A when metabolized.
Retinol (vitamin A) is an essential nutrient associated with three important functions, the best-defined of which involves human vision. Retinol is a functional constituent of rhodopsin, a protein located in the retina of the eye that absorbs light and triggers a series of biochemical reactions that ultimately initiate nerve impulses, resulting in sight.
Secondly, vitamin A is involved in the activation of gene expression and the control of cell differentiation. It is through this function that vitamin A affects immune function, taste, hearing, appetite, skin renewal, bone development, and growth.
Vitamin A's third role involves control of embryonic development. Here it is thought that retinoic acid modulates the expression of certain genes that govern patterns of sequential development of various tissues and organs in the body.
Vitamin A deficiency is a major public health issue, particularly in developing countries. It has been estimated that 500,000 preschool-age children worldwide become blind each year as a result of vitamin A deficiency. Millions of others suffer from night blindness, a common clinical sign of inadequate vitamin A intake. Further estimates suggest that more than 100 million children worldwide suffer from vitamin A inadequacy without showing clinical signs of acute deficiency. Beta-carotene is known to be an effective dietary cure for vitamin A deficiency and an effective remedy for symptoms of this disorder.
Epidemiological studies support long-term beneficial effects of beta-carotene intake on a number of degenerative diseases. For example, the relationship between beta-carotene intake and cancer has received considerable attention in recent years. Epidemiological evidence suggests that long-term intake of dietary beta-carotene may reduce the risk of several types of cancer. Similar findings pertain to heart disease and immune health.
Dietary sources rich in beta carotene and other provitamin A carotenoids include carrots, broccoli, yellow squash, corn, tomatoes, papayas, oranges, and dark green leafy vegetables like spinach, kale and Chinese cabbage. Beta-carotene is heat stable, so it is not degraded during prolonged boiling or microwaving.
Beta-carotene is one of the best known carotenoids, likely because: (1) it is one of the most abundant in a typical adult diet, and (2) it provides two nutritional functions - in addition to its role as an antioxidant, the human body converts beta-carotene into vitamin A.
Other members of the antioxidant carotenoid family include alpha-carotene, cryptoxanthin, zeaxanthin, lutein, and lycopene. Unlike beta-carotene, most of these nutrients are not converted to vitamin A in significant amounts.
Beta carotene's role as an antioxidant is based on its extensive system of conjugated double bonds which, upon reacting with an oxygen atom, absorb and diffuse that oxygen's potentially destructive energy. The oxygen atom returns to a lower energy state, and beta carotene dissipates the absorbed energy harmlessly (as heat). Similar mechanisms are involved in quenching the oxidative potential of hydroxyl radicals and other free radical compounds.
As provitamin A, beta carotene contributes to an entirely different set of functions by supplying a portion of the body's requirement for retinol (vitamin A). In fact, a single molecule of beta-carotene can be cleaved in the body to produce two molecules of vitamin A. Other carotenoids (including alpha-carotene, gamma-carotene, and cryptoxanthin) provide provitamin A activity, but yield only one molecule of vitamin A when metabolized.
Retinol (vitamin A) is an essential nutrient associated with three important functions, the best-defined of which involves human vision. Retinol is a functional constituent of rhodopsin, a protein located in the retina of the eye that absorbs light and triggers a series of biochemical reactions that ultimately initiate nerve impulses, resulting in sight.
Secondly, vitamin A is involved in the activation of gene expression and the control of cell differentiation. It is through this function that vitamin A affects immune function, taste, hearing, appetite, skin renewal, bone development, and growth.
Vitamin A's third role involves control of embryonic development. Here it is thought that retinoic acid modulates the expression of certain genes that govern patterns of sequential development of various tissues and organs in the body.
Vitamin A deficiency is a major public health issue, particularly in developing countries. It has been estimated that 500,000 preschool-age children worldwide become blind each year as a result of vitamin A deficiency. Millions of others suffer from night blindness, a common clinical sign of inadequate vitamin A intake. Further estimates suggest that more than 100 million children worldwide suffer from vitamin A inadequacy without showing clinical signs of acute deficiency. Beta-carotene is known to be an effective dietary cure for vitamin A deficiency and an effective remedy for symptoms of this disorder.
Epidemiological studies support long-term beneficial effects of beta-carotene intake on a number of degenerative diseases. For example, the relationship between beta-carotene intake and cancer has received considerable attention in recent years. Epidemiological evidence suggests that long-term intake of dietary beta-carotene may reduce the risk of several types of cancer. Similar findings pertain to heart disease and immune health.
Dietary sources rich in beta carotene and other provitamin A carotenoids include carrots, broccoli, yellow squash, corn, tomatoes, papayas, oranges, and dark green leafy vegetables like spinach, kale and Chinese cabbage. Beta-carotene is heat stable, so it is not degraded during prolonged boiling or microwaving.
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