Observation on Bone and Joint Health

Introduction
Arthritis and osteoporosis are major public health concerns that often remain recalcitrant to conventional medical interventions1 Osteoporosis is a disease of bone that is characterized by a diminution in bone tissue mass per unit volume. This bone thinning results in weakness of the skeleton and a pre-disposition to bone fractures1. In individuals with osteoporosis bone resorption appears to be increased, whereas bone formation may be normal or defective.

Osteoporosis goes “hand in hand” with osteoarthritis in many people2 . Osteoarthritis is primarily a disease affecting hyaline cartilage and adjacent bones. In more advanced cases of osteoarthritis the tissue in and around the joints becomes hypertrophic3 . Osteoarthritis seems to occur invariably with advancing age. It is the most common form of arthritis and it is universal in males and females after the age of 65 years, even though it may be asymptomatic3 .

Both osteoporosis and osteoarthritis have poorly defined etiologies (Tables 1,2 and 3). Recent research has implicated nutritional factors as important in the maintenance of bone and joint health. Despite the increasing recognition that osteoarthritis and osteoporosis may have nutritional abnormalities at the root of their causation, dietary manipulations have often played a secondary role in the management of these diseases. Recently, nutritional interventions have been increasingly proposed as potentially effective options for these disorders, which are often unresponsive to current, conventional medical interventions4,5 .

Types of Osteoporosis and Osteoarthritis
Osteoporosis is a common phenomenon in the post-menopausal and post-andropausal adult. This type of osteoporosis has been termed Type 1 and it is up to ten times more common in females than in males. Type 1 osteoporosis tends to effect cancellous bones such as the vertebral column and it has been repeatedly linked to hormonal changes that occur in the post-menopausal female, notably estrogen deficiency6 . The importance of the life-long deficiency of calcium in causing this disorder has been somewhat underestimated7 . In contrast, Type II osteoporosis (senile osteoporosis) is more related to nutritional factors such as deficiency of vitamin D or resistance to the bone related effects of this vitamin. Calcium deficiency is of significant importance in the causation of senile osteoporosis7 .

In common with Type 1 osteoporosis, Type II osteoporosis is generally more common in females but the apparent increased prevalence of this disorder may be related to the fact that women live longer than men. A number of risk factors for Type 1 and Type II osteoporosis have been identified. These are summarized in Table 2. Osteoporosis can be secondary to a variety of readily identifiable causes (Table 3) but secondary osteoporosis accounts for less than one in twenty of all cases of all forms of osteoarthritis. Type 1 and Type II osteoporosis may occur together and in some circumstances they may be exacerbated by some of the causes of secondary osteoporosis that are listed in Table 3.
Dr Connie W. Bales PhD and her colleagues8 from Duke University Medical Centre3 indicate that the lifetime risk of a woman to develop a hip fracture is much greater in the presence of osteoporosis and this risk is equal to a woman’s combined risk of developing ovarian, uterine and breast cancer. This devastating projection is even worse when one considers the fact that elderly females often die shortly after the occurrence of a fractured hip or remain bed-bound in their elderly years1 .

The link between nutrition and osteoarthritis is less clear than it is in the case of osteoporosis (Table 1 and 2). However, contemporary thinking has been directed to the consideration that osteoarthritis is related to “malnourished” cartilage. Osteoarthritis has been classified as primary or secondary to a variety of causes. Several etiologic factors may act in a synergistic manner in the causation of joint disease (Table 3). The common causes of secondary osteoarthritis are highlighted in Table 4. It is believed that the most common form of osteoarthritis may be related in part to the “wear and tear” of joints. The recognition that osteoarthritis is a disease of cartilage has precipitated research into the many mechanisms that could alter the microenvironment of cartilage and factors that nourish and protect the tissue from damage5 .

Osteoarthritis: A Disease of Cartilage.
Hyaline cartilage was for many years considered to be quite a “boring” tissue. Healthy cartilage is devoid of blood vessels, nerve fibers and lymphatics. When studied histologically, it is apparent that only a small amount of cartilage is composed of cells (chondrocytes). Chondrocytes are quite conservative. They have a “slow” cell cycle and rarely undergo cell division, unless stimulated to do so by noxious changes in their environment. In contrast to the relative lack of dynamic events in cartilage, this tissue has versatile physical properties that result in the reduction of friction in articulating joints9 . It is movement within joints that permits cartilage to retain its vitality. Compressive forces on cartilage allow it to absorb nutrients and eliminate waste products. These physical and chemical factors promote the health of the chondrocytes and their matrix9 .

Recent research has indicated that certain changes in the micro-environment of cartilage may precipitate the mitosis of chondrocytes and provide stimuli to increase the synthesis of some of the components of the matrix of cartilage9 . The proliferation of chondrocytes is an early event in the development of osteoarthritis. Progression of the disease is accompanied by a variable degree of increased synthesis of adjacent bone, proliferation of synovial cells, that line the joints, and other degenerative changes in the joints. These pathological changes occur over a variable time frame and they may culminate in gross distortion of joints. Thus, a natural evolution in the therapy of osteoarthritis is to apply options that will protect cartilage from damage (chondroprotection), by the use of “chondroprotective” agents5 .

Does Protomorphogenisis Make Sense?
Recent research has indicated that several nutrients found in cartilage are important in the maintenance of joint health5 . The idea of administering a tissue as a dietary substrate to promote health is in a similar tissue that is damaged is part of the concept of protomorphogenesis. It has been known for many centuries in traditional Chinese medical practice that the eating of cartilage itself may promote the health of joints. The use of animal cartilage in food to promote joint health is ingrained in the culinary habits of several South East Asian countries. Large joints of the cow are shaved and spiced to form one of the most popular meals in Korea and Northern China. This dish, and a condensed soup prepared from the joints of large animals, have been used for centuries to promote the health of joints. The importance of the components of cartilage in promoting the health of joints is well illustrated by recent research in the dietary supplement industry. The components of cartilage that may have a benefit in arthritis therapy and bone or joint health are summarized in Table 5.

Age effects bone mass and joint mobility9 . Peak bone mass is reached in males and females between the age of 20 and 30 years. It is known that the level of bone density at the time of peak bone mass is an important factor for determining bone health throughout the later years of life8. Individuals in Western society lose up to 0.5 % of bone mass on an annual basis and this reduction in bone density accelerates after the menopause8 . Good nutrition undoubtedly plays a major role in determining the achievement of optimal bone density but weight-baring exercise is a proven way of increasing bone density without any form of therapy, nutritional or otherwise. The author believes that many accounts of the prevention or treatment of osteoporosis and osteoarthritis fail to recognize the importance of a regular program of exercise that involves repeated muscular activity against gravity.

Towards the Optimal Diet
Calcium intake is important in the maintenance of skeletal health7 . When considering the optimal diet for the prevention or management of osteoporosis it must be recognized that osteoporosis is not related simply to low calcium intake. In 1994, the National Institutes of Health drew attention to the importance of calcium deficiency in the causation of osteoporosis during a Consensus Development Conference7 . Whilst it is recognized that it is adequate calcium intake in the diet that is pivotal in the maintenance of bone health, many epidemiological studies show that there is not a direct relationship between calcium intake and the incidence or prevalence of osteoporosis4 . In many South East Asian countries, calcium intake is less than that in Western Society4 . However, the prevalence of osteoporosis and its consequences, notably bony fractures, is lower in many South East Asian countries, and several Third World countries, where calcium intake may be quite low4 .

Several epidemiological studies, that were primarily conducted to examine the importance of calcium intake on bone health, have served the more important purpose of showing scientists that osteoporosis is a multifactorial disease4,8,9 . Whilst calcium is important, it is not the whole answer. There are racial and ethnic differences in the amount of calcium required in the diet to maintain normal calcium balance. Fracture rates in populations are often used as indicators of the prevalence of osteoporosis but it is recognized that calcification of bone may not be the only factor that determines bone strength10 . There may be major changes in other supporting structures in bone which could account for its weakness and tendency to break10 .

Focus on Calcium and Osteoporosis
Life long calcium deficiency is a very important, widely accepted cause of osteoporosis7 . Several studies have reported favorable reductions in bone loss in postmenopausal women who have received calcium or estrogen replacement therapy or both4,6-8 . Other studies, using multiple nutrient therapy with calcium as a focus of treatment, have produced similar beneficial results in the treatment of osteoporosis8 . Important studies using calcium supplementation of the diet have indicated a reduction in the prevalence of osteoporotic vertebral crush fractures in post-menopausal women8 . Estrogen supplements are given to post-menopausal women to reduce menopausal symptoms and, arguably, to promote cardiovascular health and reduce osteoporosis6 . However, estrogen and other synthetic hormonal supplements have unfortunate adverse effects and risks, such as the promotion of uterine and breast cancer4,6 .

The beneficial effects of calcium supplementation on bone loss in premenopausal and postmenopausal “middle-aged women” is well recognized7 . A study by Dr Dawson-Hughes M.D. and his colleagues11 (1987) showed that women had a loss of bone density when they had a daily calcium consumption of less than 400mg/day. Loss of bone density was much less in those women who had a calcium intake of approximately 750mg/day. Although some other studies have failed to show a major beneficial effect of calcium supplementation in preventing or reversing osteoporosis, an overwhelming body of opinion is in favor of calcium supplementation as a preventive measure for osteoporosis7,8,11,12 .

Accepting the importance of dietary calcium supplementation, the amount and chemical type of calcium and the source and format of calcium in the diet are believed to be important variables in the promotion of bone health7 (Table 6). The Recommended Daily Allowance (RDA) of calcium in the diet is 800mg/day for adults and 1-2g/day for young adults7 . Several studies have indicated that calcium intake in many diets may often be below the RDA, especially in the elderly7 . There are several adverse effects of taking too much calcium in the diet, especially if an individual is otherwise not healthy and particularly if renal failure is present4.7 .

Diet and Osteoporosis
Several authors have drawn particular attention to diet as a determinant of bone and joint health4,8,12 . Several dietary factors that have been associated with the development of osteoporosis include excessive protein intake in the diet, excessive phosphorus consumption and high sodium intake13 . There is convincing evidence that excessive dietary intakes of animal protein may be related to the pathogenesis of osteoporosis4,8,12 . The potential role of excess protein intake is illustrated by studying the hip fracture rate versus animal protein intake in various countries4 (Table 7). Some studies indicate that individuals who maintain a vegetarian diet may have less osteoporosis than omnivorous individuals, but some of these data are conflicting4 .

Table 6 emphasizes the apparent strong relationship between animal protein intake in many countries and hip fractures. The occurrence of hip fractures can be largely attributed to osteoporosis and it is used as an indirect measure of the prevalence of osteoporosis. The type of protein in the diet (animal versus vegetable) seems important, with vegetable protein affording a preventive effect against osteoporosis4 . The whole issue of food processing as a cause of reductions in the nutrient value of many foods has been well reviewed and food processing is believed to contribute indirectly to the causation of osteoporosis and other chronic diseases that may be related to nutrient deficiencies4,8,12,13 .

Preventing Osteoporosis
Scientific literature often focuses on the prevention and therapy of osteoporosis, but overall the results of treatment of established osteoporosis are disappointing. Contemporary literature draws attention to alternative medical and primary nutrient approach to osteoporosis therapy8,12,13 . The possibility that sugar, caffeine, salt and alcohol and other potentially harmful dietary constituents promote osteoporosis13 is very plausible. In addition to the relatively poor nutrient value of processed foods, poor soil quality and pollution of farmland are factors that determine the inadequate nutrient value of crops13 . All of these factors may play an indirect role in promoting osteoporosis and other diseases4,8,12,13 .

A whole host of other dietary factors and micronutrients may play a variable part in promoting skeletal health, including vitamin K, B6, C and D, manganese, magnesium, vitamin B6, folic acid, strontium, boron, zinc, copper, silicon8,12,13 . Calcium, phosphorus and vitamin D appear to play the most important role in maintaining a healthy skeletal function, compared with all of these other dietary factors8,12,13 .

The classic guidelines of the Food Guide Pyramid are not adequate for individuals who are at risk of osteoporosis. Dr Connie W Bales and her colleagues8 have recommended that these existing dietary guidelines of 2 or 3 daily servings of dairy products be replaced by 4 or 5 daily servings of low-fat, dairy products to increase the daily intake of calcium, in order to prevent osteoporosis. The author proposes that there are more efficient dietary maneuvers that will prevent osteoporosis without resorting to enhanced intake of dairy products. Such maneuvers include the avoidance of the “calcium wasting” effects of excessive animal protein and the inclusion of “healthier”, calcium-fortified foods, together with the inclusion of soy isoflavones in the diet4 . These circumstances are ideal for the correct selection and application of well formulated dietary supplements which offer convenience for the busy adult who cannot direct their attention to meticulous dietary habits.

Switching to Vegetable-Based Diets
There seem to be several compelling reasons to switch from animal protein diets to fruit and vegetable diets that are rich in fruit and vegetables, in order to achieve optimal bone and joint health4,8,12,13 . Examples of these benefits are most apparent particularly when one examines the benefits of fractions of certain legumes, such as soybeans4,6 . It is recognized that soy protein inclusion in diets may promote calcium retention in the body14 . In contrast, animal protein may tend to increase calcium excretion in the urine, lower urinary citrate excretion and increase uric acid excretion14 . As well as a negative impact on bone health, these circumstances may lead to a tendency to form urinary calculi (stones)14 .

Dr P. Kontessis MD and his colleagues15 studied the renal, metabolic, and hormonal responses to animal and vegetable protein diets and observed enhancement of renal function with the use of a vegetable protein diet. This clinical investigation showed the greater efficiency with which the human kidney can handle vegetable protein compared with the efficiency of handling animal protein15 . It was found that the glomerular filtration rate was about one fifth higher after the dietary inclusion animal protein than after soya protein15 .

Fruit and vegetable diets can deliver a vast array of health giving phytonutrients that have versatile health giving benefits including anticancer effects and antioxidant effects4,8,12,13 . These agents have direct benefits for the maintenance of health of the chondrocyte and other metabolically active cells. Of particular importance in some vegetarian diets is the presence of soy isoflavones (genistein, daidzein and glycitein) from soybeans that have been shown to be preventative and therapeutic in osteoporosis in double-blind controlled clinical studies4,6,10

Clarifying Recommendations for Diet
Both dietary excesses and dietary inadequacies play a role in bone health and general well being8,12,13. The concept of the balanced diet for bones and joints is worth summarizing by considering many of the most important nutrients for skeletal health (Table 8). The switch towards a vegetarian diet does not necessarily need to be complete to promote health4 . A well balanced omnivorous diet can be healthy provided that animal protein and fat intake is limited4,8,12,13 . The Western diet is characteristically too high in cholesterol, saturated fat and animal protein4 . Dairy products have been overemphasized as an important dietary component for healthy bones and teeth and several reasons exist to limit dairy produce in the diet16 . Dairy products present a high cholesterol load with the risk of the promotion of cardiovascular disease4 . Dairy products may precipitate milk protein allergy and they often deliver a high caloric and high, saturated-fat load16 .

A balanced diet for bone health should limit caffeine, alcohol, simple sugar, saturated fat, excessive animal protein, excessive phosphorus and high salt intake8,12,13. Each of these elements of Western diets have been shown to exert one or more deleterious effects on the bone and joint health8,12,13 . Finally, the role of obesity in the pathogenesis of osteoarthritis and perhaps osteoporosis is unquestionable9 . Excess body weight provides stresses on weight-bearing bones and joints. This results in premature “wear and tear” of the skeleton9 . The Western diet often contains too many calories, derived especially from fat (as much as 150-180gm of fat per day in Europe and the USA). Calorie restriction is of pivotal importance in weight reduction and low energy density foods are to be preferred in many cases4,8 . The switch to vegetables in the diet often achieves calorie restriction in a gradual and comfortable manner4 . Vegetables can promote satiety because of their relatively low calorie bulk and fiber content. Dietary fiber promotes health in general but care is advised with excessive intake of coarse fiber, such as bran, which can limit calcium absorption4 .

The Antiporosis Plan
Readers who are intereseted can take the osteoporosis risk questionnaire shown below: insert

Insert Section 6 [of book antiporosis plan]

Conclusion
Recent research has pointed the way to an optimal diet for the prevention and treatment of bone and joint disorders. Enactment of more universal nutritional approaches to osteoporosis and osteoarthritis will pave the way to the eradication of these disease4,8,12,13

• Female Sex
• Premature Menopause
• Advanced Age
• Race (commoner in whites)
• Lifelong Calcium Deficiency
• Lack of Exercise
• Genetic Predisposition
• Ectomorphic Build
• Nulliparity
• Low Phytonutrient Intake
• Trace Metal Deficiency
Table 2: Risk factors described for primary osteoporosis

DRUG INDUCED:
Alcohol, Tobacco, Barbiturates, Phenytoin, Heparin and Corticosteroids.

ENDOCRINE DISORDERS:
Diabetes mellitus, Excess glucocorticoids, Hyperparathyroidism, Hyperthyroidism, Hypogonadism, Hyperprolactinemia,

MISCELLANEOUS FACTORS:
Lack of Exercise (especially immobilization), Kidney disease, Arthritis (interfering with locomotor ability), Cancer, Liver disease, Intestinal disease (causing malabsorption) and Chronic pulmonary disorders.

Table 3: Causes of secondary osteoporosis

• Trauma to joints and adjacent fracture of bones.
• Metabolic and endocrine disease.
• Neuropathic disease.
• Congenital disorders of joints.
• Secondary to other types of arthritis e.g. rheumatoid disease.
• Overuse of joints.
• Infections of joints.

Table 4: Factors that may cause secondary osteoarthritis

Stage of Life Optimal Daily Intake (in mg of calcium)

Women
25-50 years 1000
Pregnant and nursing 1200-1500
Over 50 years post-menopausal
On estrogens 1000
Not on estrogens 1500
Over 65 years 1500
Men
25-65 years 1000
Over 65 years 1500
Adolescents/Young Adults
11-24 years 1200-1500
Children
Up to 10 years 800-1200
Infants
Up to 1 year 400-600

Table 6: Optimal calcium requirements during an individuals lifetime

Animal Protein Hip Fracture intake (approximate rate (per100,000 Country g/day) people)

South Africa
(blacks) 10.4 6.8
New Guinea 16.4 3.1
Singapore 24.7 21.6
Yugoslavia 27.3 27.6
Hong Kong 34.6 45.6
Israel 42.5 93.2
Spain 47.6 42.4
Holland 54.3 87.7
United Kingdom 56.6 118.2
Denmark 58.0 165.3
Sweden 59.4 187.8
Finland 60.5 111.2
Ireland 61.4 76.0
Norway 66.6 190.4
United States 72.0 144.9
New Zealand 77.8 119.0
Table 7: Relationship between animal protein intake and hip fracture rate

Nutrient Comment

Calcium Unequivocal evidence for benefit.
Fluoride Trace amounts are beneficial, overinclusion damages bones.
Silica Enhances bone mineralization and function of bone collagen.
Zinc Facilitates calcium absorption and is necessary for enzyme systems
in matrix building, antioxidant properties.
Manganese Essential role in cartilage and collagen formation in the skeleton.
Boron Facilitates calcium and magnesium utilization and function.
Magnesium Facilitates calcium, vitamin D and hormonal effects on bones.
Phosphorus Combines with calcium in salts in bones and is vital for many
cellular functions.
Copper Facilitates collagen and matrix synthesis.

Vitamins A,B3,B6, C,D,B12,K,Folate Vitamin D is the most important regulator of calcium and phosphorus metabolism. B3 and B6 are enzymatic co-factors in collagen metabolism. A is vital in osteoblast function and it regulates calcium metabolism. C is vital for healthy collagen synthesis. K is necessary for osteocalcin synthesis, the matrix upon which calcium is deposited in bone. B12 promotes chondrocytic and osteoblastic metabolism. Folate is anti-homocysteine, thereby being anti-osteoporotic and anti-atherosclerotic.

Essential Fatty Essential for calcium metabolism and cell membrane function Acids. The ratio of Omega-3 to Omega-6 fatty acids is distorted in Western diets. Many diets are Omega-3 deficient.

Table 8: Nutrients required in a balanced diet for bone health

Component Therapeutic Potential

• Calcium and Phosphorus Ideal, balanced, bioavailable mineral in a 2:1 ratio supplement for bones (prevents osteoporosis)

• Collagen, Type 2 A nutrient with potential for the development of the immune tolerance phenomenon (e.g. rheumatoid and connective tissue disease).

• Glycosaminoglycams Anti-inflammatory and immunomodulating agents (suppress inflammation , enhance immune function with T cell and natural killer cell modulating activity).

• Antiangiogenic Protein Varying molecular weight antiangiogenic proteins have been repeatedly demonstrated in shark cartilage. The molecular weight of some of these proteins is such that they may cross the intestinal mucosal barrier. Potential action in many angiogenesis-dependent diseases, e.g. cancer, arthritis, skin disease, proliferative retinopathy, Kaposis sarcoma.

• Chondroitin sulfate, Regarded as potential therapy for arthritis.
Heparan sulfate,
Dermatan sulfate,
Keratan sulfate

Table 5: Constituents of shark cartilage that may confer a health benefit in several disease states. Potential mechanisms of actions and applications are summarized.

ETIOLOGICAL FACTOR COMMENT – CIRCUMSTANCE

Genetics – Heredofamilial Procollagen gene (COL2A1) defects
tendancies. Heberden’s nodes
Postural defects
Idiopathic generalized osteoarthritis

Crystalline deposition in joints Uric acid
Calcium pyrophosphate
Hydroxyapatite

Advanced age Defects in collagen structure in cartilage
Spontaneous cartilage fractures
Diminished aggregation of proteoglycans
Lack of resilience of supporting tissues
Abnormal anatomical circumstances

Repetitive stress Excessive sports activity
Coexistent neuropathey
Muscular dystrophy

Poor nutrition Deficiency of antioxidants, key vitamins and
minerals that are important for metabolic function
in chondrocytes and matrix formation of cartilage.

Metabolic diseases Acromegaly
Copper storage disease
Ochronosis

Eccentric mechanical stress Joint instability
Hypermobility
Previous trauma to cartilage
Postural defects
Abnormal joint development
Obesity

Previous joint infection Syphilis
Gonoccal arthritis
Pyogenic arthritis

Table 1: Some of the factors in the etiology of osteoarthritis. The commonest factors contributing to osteoarthritis in Western society are advancing age, trauma and obesity.

References
1. National Osteoporosis Foundation, national Objectives for Disease Prevention and Health Promotion for the Year 2000. National Osteoporosis Foundation, Washington D.C., 1988.
2. Nevitt, M.C. Epidemiology of Osteoporosis. Rheumatic Disease Clinics of North America 20.3 535:559, 1994.
3. Felson, D.T., Naimark, A., Anderson, J. et al, The prevalence of knee osteoarthritis. The Framingham Study. Ann Intern Med 109:18, 1988.
4. Holt, S. Soya for Health. Mary Ann Liebert Inc., Larchmont, NY, 1996.
5. Theodosakis, J., Adderly, B., Fox, B., The Arthritis Cure. St Martins Press, NY, 1997.
6. Holt, S. Phytoestrogens for a Healthier Menopause. Alternative and Complementary Therapies, April, 1997, 1-5.
7. NIH, Optimal Calcium Intake. National Institute of Health 12.4. 1-24, 1994.
8. Bales C.W., Drezner M.K., Hoben K.P., Eating Well, Living Well with Osteoporosis: Duke University Medical Centre. Viking, Penguin Books
Inc. NY, NY, 1996.
9. Anderson, J.J., Felson, D.T., Factors associated with osteoarthritis of the knee in the first national health and nutrition examination survey (Hanes I). Evidence for an association with overweight race and physical demands of work. AM J Epidemiol 128:179, 1988.
10. Second International Symposium on the Role of Soy in Preventing and treating Chronic Disease, Brussels, Belgium, September 15-18, 1996
Program and Abstract Book; proceedings to be published in J Coll Nutr 1997-8.
11. Dawson-Hughes B., Jacques P., Shipp C. Dietary calcium intake and bone loss from the spine in healthy postmenopausal women. Am J Clin
Nutr 46:685-687, 1987.
12. Brown, S.E.. Better Bones, Better Body, Keats Publishing Inc. New Canaan, CT, 1996.
13. Gaby, A.R., Wright, J.V., Nutrients and Bone Health. Health World, 1988, 29-31.
14. Holt, S., Likver, L., Muntyan, I. The Vegetarian Way to a healthy Urinary Tract. Alternative and Complimentary therapies –
May/June1996, 10-15.
15. Kontessis, P., Jones, S., Dodds R., Trevisan, R., Nosadini, R., Fioretto, P., Borsato, M., Sacerdoti, D., Viberti, G., Renal, metabolic and
hormonal responses to ingestion of animal and vegetable proteins. Kidney Int 38:136-144,1990.
16. Holt, S., The Health Food of the Next Millennium. International Symposium on Soymilk and Cow’s Milk. Spring Meeting of Korea Soybean Society. Korea Soybean Digest, Vol. 14, No. 1, July 1997.

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