Bone Health Diet

Our nutrition and diet has an essential impact on bone health. Measures to promote bone health throughout one's life are of obvious importance. To assist in building bone and to reduce losses of bone with advancement in age, it is necessary to educate ourselves about general bone health and the role that calcium plays in our body. According to most of the proficient nutritionists, our bones, on an average, reach their maturity level of density in the mid 20s. After the age of 35, both men and women start losing bone. The phenomenon occurs gradually at the rate of 1-2 per cent per year. In case of female, the rate of this bone loss gets accelerated to around 5 per cent per year around menopausal period. The most abundant mineral in an individual's body, calcium provides strength to bones while proteins form the underlying structure of bones. The body functions to keep the calcium level in blood within a narrow range. It regulates the absorption of calcium from the gut and bone and loss of calcium in urine. But, in elderly people, these regulatory mechanisms prove to be inadequate in preserving bone. Continuous loss of calcium in older people leads to thinning of bones, a major public health issue faced by all the developed countries. Thinning bones increase the risk of fracture in individuals.

Five key points to promote bone health are :

1. Provide the ingredients of bone
Protein, phosphorous and calcium are the chief ingredients of bone. Adequate intake of these ingredients through diet is essential for bone health. Around 1.0 g of protein per kg of body weight per day is the adequate amount required for most people, over the age of ten. The adequate intake of phosphorous and calcium in most people are 1.25 g per day and 800-1500 mg per day respectively. Given below is a chart that shows the calorie and calcium content of a variety of foods.

Sardines in Tomato Sauce	Skimmed Milk	Natural Yoghurt	Fruit Yoghurt	Cheddar Cheese	Baked Beans
Peeled Prawns	Spring Greens	Orange	Cottage Cheese	White Bread	Sesame Seeds
	Wholemeal Bread	Cooked Broccoli	Unsalted Peanuts	Dried Apricots

Calorie and calcium content of selected food

2. Reduce calcium losses from the body
The body loses calcium in three ways - through urine, gut secretions and sweat. One can avoid bone loss if the absorption of calcium from food in the gut balances its loss. If the loss of calcium does not get balanced, the body will ultimately take calcium from bone to keep the required calcium level in the blood intact. If loss of calcium in an individual's body exceeds absorption from the gut by 30 mg per day, the bone will lose 1% of its calcium each year. People who have typical North American and European dietary habits can lose calcium by the intake of four dietary components - high sodium, high protein, low potassium and low bi-carbonate.

Due to the increased or decreased intake of these components, the additional calcium losses can be as follows :

• Increasing sodium intake from 1000 to 4000 mg/ day increases loss of calcium by 52 mg/ day
• Increasing protein intake from 40 to 100 g/ day increases loss of calcium by 66 mg/ day
• Decreasing potassium intake from 8000 to 2000 mg/ day increases loss of calcium by 31 mg/day
• Decreasing bi-carbonate intake from 100 to 20 mmol/ day increases loss of calcium by 32 mg/ day

3. Make absorption of calcium from the gut easy
Foods can be categorised depending on their calcium content and the increase and decrease of calcium losses they cause. To boost bone health, one needs to consume foods that contain high amount of calcium but cause less calcium losses. These types of food are considered to be ideal and therefore can benefit everyone. Kale and spring greens (leafy vegetables) are the finest examples of such foods. Though dairy foods provide high content of calcium, they also cause high calcium losses. Foods like meat, fish and eggs have less content of calcium but are responsible for high calcium losses, upsetting the calcium balance. Low calcium foods like peppers, bananas and oranges provide a modest boost as well as reduce calcium losses. Fruits and vegetables are ideal foods for those looking to improve their calcium balance. They have rich content of potassium and bi-carbonate and these components help reduce calcium losses. Though increased intake of protein leads to calcium losses, an adequate protein intake is always essential both for muscles and bones.

4. Make absorption of calcium from bone difficult
Reduce the intake of sodium and increase the intake of potassium and bi-carbonate to reduce calcium losses. For instance, a reduction in salt intake by 5 g/ day will eliminate 2000 mg of sodium. This in turn will reduce your calcium losses by about 35 mg/ day. The intake of potassium and bi-carbonate can be increased by taking fruits and vegetables. In this case, legumes can be the source of protein, rather than meat, fish or egg. Reduction in calcium losses can also be brought about by having green leafy vegetables in lieu of dairy products. Reducing calcium losses while at the same time consuming an adequate amount of calcium (1000 mg/ day) can really lead to a sturdy bone foundation. Loss of calcium from bone will reduce if calcium is promptly available from food in the gut.

5. Promote bone strength independently of bone mass
The building of bone mass and its demolition is an ongoing process. Bone is comprised of osteoblast cells while it is destroyed by osteoclast cells. The renewal and the repair of bone depends on these two types of cells. To make the bone resistant to the demand of releasing calcium in the blood, it is essential to bolster the osteoblast activity, as compared to the osteoclast activity. As the bones become more and more resistant to the demand, the body will meet its calcium losses by absorption from food in the gut. Growth harmones, particularly in childhood and adolescence, act as an stimulating agent for the osteoblast activity. But as growth hormones decline with age, the promotion of positive calcium balance becomes unlikely in older people. Oestrogen, the levels of which also decline with age, also plays a vital role in keeping the calcium balance positive. A chief protein component of bone, osteocalcin is produced by osteoblast cells. Carboxylated osteocalcin can effectively bind with calcium. Elevated undercarboxylated osteocalcin (ucOC) leads to risk fracture and reduced bone density. Elevated ucOC can be adjusted by increasing the intake of vitamin K, found in green leafy vegetables, broccoli, fermented soya products, natto etc. An increased intake of vitamin K (250 mg/ day) can reduce fracture risk by almost 65%.

Along with plenty of calcium intake, vitamin K also plays an important role in ensuring a beneficial effect of increased levels of vitamin D. To determine the adequate intake of vitamin D for individuals, serum 25 (OH)D is considered to be the chief indicator. Vitamin D is scantily available in food, except from a few including fish liver oil, flesh of fatty fish, liver and fat of aquatic mammals etc. Vitamin D content in fish is around 1600 IU/ 100 gm. People mostly fulfill their vitamin D intake requirement through fortified milk products and other fortified food. Both sunlights and diet are considered to be the essential source of vitamin D for people between the age of 19 - 30 and 31- 50. Supplement users (both men and women) are recommended 200 IU/ day intake of vitamin D.

Recommended Dietary Intake of Vitamin D
Children - 10 micrograms (400 IU)/ day
Adults (up to 50 years) - 5 micrograms (200 IU)/ day (An additional dose of 5 micrograms/ day will be required during pregnancy and lactation)
Adults (51 - 70 years) - 10 micrograms (400 IU)/ day
Adults (above 70 years) - 15 micrograms (600 IU)/ day

[Milk, meat, fruit and vegetables are not rich sources of vitamin D.]

Fish is the only rich natural source of vitamin D. Fish like herring, catfish, salmon, mackerel, tuna and eel are some examples of fatty fish that contain good amount of vitamin D.

Cod Liver Oil : 1 Tbs (15 ml) = 1360 IU of Vit D

Elderly people, dark skinned people and those who are exposed to inadequate Ultraviolet radiation (i.e. sunlight) consume extra doses of vitamin D from vitamin D fortified food and supplements. Individuals who fall in this high risk group need to consume 25 MG (1000 IU) of vitamin D everyday to control the adequate blood concentrations of 25-Hydroxyvitamin D, the biomaker for vitamin D status.