Dietary Approaches for Bone Health
Queenie Woo, HK BioTek Intern
Bone is a vital, dynamic connective tissue that provides structural support, protection and fixation of muscles for the human body. After reaching peak bone density at about 30 years of age, bone mass is lost gradually along with aging. In particular, the process of bone loss is accelerated as women experience hormonal changes such as menopause. As bone is lost to a certain extent, bone structure becomes fragile and eventually develops into osteoporosis, causing fractures and other complications. Apart from the aforementioned factors, diet is a modifiable osteoporosis risk factor, and plays an important role in the acquisition and maintenance of bone mass. The influence of diet on bone begins in childhood; even maternal diet can influence bone mass in the offspring.
The first step of maintaining bone health: Calcium Intake
It is a well-known fact that calcium is a mineral we need for overall health and to keep our bones strong. Calcium is a major nutrient which constitutes bones and teeth. Adequate intake of calcium can strengthen bones and reduce the risk of fractures. However, the concentration of calcium is tightly regulated and it is not stored in bones for an extended period. Bone itself undergoes continuous remodeling, with constant resorption and deposition of calcium into new bone. When the dietary intake of calcium is insufficient, the secretion of parathyroid hormone in the body will increase, speeding up the decomposition of bone and releasing calcium ions into the blood. Therefore, there will be a risk of bone loss if the body is under the state of calcium deficiency. Current available scientific evidence stated that high-risk groups such as middle-aged and elderly people, as well as postmenopausal women, could efficiently increase their bone density and reduce the risk of fractures through accommodating a diet with adequate calcium intake.
In addition, it is worth noting that excessive intake of calcium could cause side effects such as cramps and constipation, and may also affect the absorption of iron and zinc, which may induce kidney stones. Consequently, it is crucial to note that daily calcium absorption should not exceed the recommended upper limit. With reference to the National Osteoporosis Foundation of the United States, under normal circumstances, the daily intake limit for people aged 19-50 is 2,500 mg, and for people aged 51 or older, the suggested upper limit is 2,000 mg.
Foods rich in calcium:
Dairy products: milk, cheese, yogurt, etc. (Recommend to select skimmed milk or other low-fat dairy products to avoid being overweight).
Fish: seafood eaten with bones or shells, such as plimsolls, sardines, dried whitebait and dried shrimps.
Beans/bean products: soybeans, black-eyed beans, firm tofu, soy milk fortified with calcium, vegetarian chicken, bean curd sheet, yuba, etc.
Vegetables: dark green vegetables, such as Chinese kale, broccoli, choy sum, etc.
Nuts: such as almonds, sesame, pistachio, peanut, cashew nut, etc.
The linkage between vitamin D and bone health
In addition to calcium, vitamin D plays an indispensable role in ensuring bone integrity. Vitamin D is responsible for regulating the absorption of calcium and the bone formation process. Human body produces vitamin D naturally when it’s directly exposed to sunlight. Vitamin D can also be acquired from certain foods and supplements. The recommended daily intake of vitamin D for people under the age of 50 is 400-800 IU, while the recommended intake for people aged over 51 is 800-1000 IU.
Foods rich in vitamin D:
Oily fish: such as tuna or sardines, fish oil, egg yolk and vitamin D supplements.
Protein intake and bone health
Dietary protein is another key nutrient for bone health across lifespan. Protein is the major component of the bone’s organic structure. Specifically, protein promotes bone formation by influencing the concentration of insulin-like growth factor-1. Adequate protein can enhance the absorption of calcium in the intestines and protect bone integrity. The recommended daily protein intake is about 10% to 15% of the daily energy required by the human body.
Both animals and plants are good sources of protein. However, which protein has a greater impact on bone quality? Despite animal proteins having higher digestibility, current research supports a diet with sufficient protein for calcium metabolism. Regardless of the source, as long as ensuring an adequate protein intake, they will both bring a positive effect on bone health.
Food sources containing animal protein: milk, eggs, fish, meat, dairy products, etc.
Food sources containing plant protein: beans, such as soybeans, lima beans, bowl beans, etc.
Rheumatoid Arthritis, a problem linked to food sensitivity?
Many studies have claimed the connection between the gut and joints. Common delayed food sensitivity may cause rheumatoid arthritis involving the wrists, knees and ankles, and even worsening the already painful condition. When people ingest food allergens, the immune system is stimulated to produce more cross-reactive food antibodies. These antibodies might attack the body's joints and lead to rheumatoid arthritis. People who are worried about their joint conditions may wish to trace their own eating habits or take the food sensitivity tests to get rid of suspected allergens.
Other Tips for Bone Health
Aside from the key nutrients mentioned above, magnesium, copper, potassium, folic acid and vitamin B ,K and C are all other nutrients required for maintaining bone health. As stated previously, dark green vegetables are rich in calcium. Nevertheless, merely relying on the intake of vegetables does not guarantee a positive influence on bone health. Experiments suggested that if one could maintain an optimal general nutritional status from a diet consisting of fruits or dried fruits (such as dried prunes), they could acquire adequate nutrients as mentioned above.
The process of bone loss involves a multi-factored mechanism. Aside from diet, other factors including age, genetics, habits of smoking, alcohol intake, physical activity and medical use such as the consumption of steroids could also affect bone health. To improve your bone health, start establishing good habits in all aspects of life: practicing a healthy lifestyle, adopting a nutritious diet along with frequent exercises!