Nutrition in bone health
Bone loss that begins in adult life and continues into old age is a normal process. Bone composition is unchanged, but mass and density decrease. Osteoporosis occurs when loss of bone density becomes so acute that the skeleton is unable to sustain ordinary stresses, a condition marked by the occurrence of fractures. Osteoporosis must be prevented early in a lifetime. 1,5 million people in the Netherlands are affected by osteoporosis, and 150000 fractures occur annually as a result. Half of these osteoporosis fractures involve the vertebrae. 20000 are fractures of the hip, which result in incapacitation, long-term nursing care, and frequently death. Statistics indicate that women are about four times more likely than men to develop osteoporosis, although with aging all people gradually lose bone mass and become more vulnerable. Because bone health is influenced by three major interacting factors – diet, exercise and oestrogen – it is never too early or too late to prevent or lessen the onset or severity of osteoporosis by increasing calcium-rich foods and engaging in regular weight-bearing exercise.
Type I, post-menopausal osteoporosis is seen in elderly women within 15 to 20 years of menopause, and it primarily involves trabecular bone.
Type II, or age-associated osteoporosis occurs around age 70 and beyond. It affects both sexes and may involve both cortical and trabecular bone.
Secondary osteoporosis results when an identifiable drug or disease process causes loss of bone tissue.
Menstrual status is a major determinant of osteoporosis risk in women. Acceleration of bone loss coincides with the menopause, at which time the ovaries stop producing oestrogen.
A striking but transient bone loss occurs in women who breastfeed for 6 months or longer. Sufficient calcium and vitamin D intake are essential during this time for the mother to replete her own serum and storage levels.
Calcium intakeThe density of bone mass attained at the time growth is complete determines to some degree what will be left after years of gradual loss. Although peak bone mass is determined by a number of factors, calcium intake from birth through adolescence is a major contributor. The influence of calcium intake during adulthood is not known, but available evidence indicates that those with a lifetime history of adequate calcium intake are less susceptible to osteoporosis at advanced ages. It is suggested to take in 1000 to 1500 mg of calcium and 400 to 800 IU of vitamin D daily.
Vitamin D intakeAdequate vitamin D intake is important. Excess should be avoided.
Trace mineral intakeTrace minerals, especially copper, manganese, zinc, boron and silicon help in preventing bone loss.
Lack of exerciseImmobility in varying degrees is well recognized as a cause of bone loss.
MedicationsA number of medications contribute to osteoporosis, either by interfering with calcium absorption or by actively promoting calcium loss from bone.
Alcohol and cigarettesCigarette smoking and excessive alcohol consumption are risk factors for developing osteoporosis.
Other dietary factorsOther dietary factors associated with bone loss include excessive fibre intake, which can interfere with calcium absorption. Protein excesses may lead to increased calcium excretion. While high calcium intakes are not significantly affected by a high protein intake, low calcium intakes are generally not sufficient to offset a high protein intake. Also important is total protein in the diet. Low levels of serum albumin negatively affect serum calcium. Elderly patients with hip fracture may benefit from protein supplements.
Populations with lower calcium intakes from dairy products have lower rates of osteoporosis and hip fractures when soy bean intake is higher. Animal protein causes hypercalciurea, while soy does not. It appears that the isoflavones in soy beans may actually inhibit bone resorption. Vegetarian diets may be more beneficial than animal protein diets.
The relationship of caffeine of osteoporosis is a controversial subject. Data now suggest that moderate caffeine intake has little or no deleterious effect on younger women who consume adequate calcium, but in older women who do not also compensate for their less effective intestinal absorption, it can have a delirious effect especially when dairy products are not also consumed.
Oestrogen replacement therapyOestrogen replacement therapy is one method for reducing bone resorption and arresting post-menopausal bone loss in women. It is most effective when used during the first 5 to 15 years after menopause. If oestrogen is started a few years after menopause, it can even reduce the fracture rate. There is some evidence that oestrogen replacement therapy combined with high calcium supplementation may even result in increased bone mineral density.
ExerciseWeight-bearing exercise that involves the pull of muscle against bone and both against gravity protects against loss of bone mass by stimulating osteoblast activity.
CalciumCalcium therapy is important in the treatment of osteoporosis.
- 1500 mg/day for adolescents aged 12 to 18 years
- 1000 to 1200 mg/day for those aged 18 to 40 years
- 800 to 1000 mg/day for women aged 40 through menopause, increasing 5 years after menopause to 1500 mg/day
- The elderly should be encouraged to consume 1500 mg of calcium and 800 IU of vitamin D daily.
Milk consumption during childhood and adolescence is beneficial for acquisition of peak bone mass. Wheat bread can be good source for those who consume a lot of bread. Green, leafy vegetables such as broccoli, kale and bok choy have good bioavailability. Soy beans are also very well absorbed.
Calcium in foods:
Yoghurt, 415 mg
Sardines in oil, 372 mg
Cooked collard greens, 357 mg
Cheese, 337 mg
Non-fat milk, 302 mg
Vanilla pudding, 298 mg
Whole milk, 291 mg
Custard, 297 mg
Buttermilk, 286 mg
Cooked rhubarb, 212 mg
Cooked spinach, 200 mg
Canned beans, 141 mg
Other treatment modalities-calcitonin