calcium
You have more calcium in your body than any other mineral. Calcium has many important jobs. The body stores more than 99 percent of its calcium in the bones and teeth to help make and keep them strong. The rest is throughout the body in blood, muscle and the fluid between cells. Your body needs calcium to help muscles and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system.
It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include
* Dairy products such as milk, cheese, and yogurt
* Leafy, green vegetables
* Fish with soft bones that you eat, such as canned sardines and salmon
* Calcium-enriched foods such as breakfast cereals, fruit juices, soy and rice drinks, and tofu. Check the product labels.
The exact amount of calcium you need depends on your age and other factors. Growing children and teenagers need more calcium than young adults. Older women need plenty of calcium to prevent osteoporosis. People who do not eat enough high-calcium foods should take a calcium supplement.
Osteoporosis is a disease that thins and weakens the bones. Your bones become fragile and break easily, especially the bones in the hip, spine, and wrist. In the United States, millions of people either already have osteoporosis or are at high risk due to low bone mass.
Anyone can develop osteoporosis, but it is more common in older women. Risk factors include
* Getting older
* Being small and thin
* Having a family history of osteoporosis
* Taking certain medicines
* Being a white or Asian woman
* Having low bone density
Osteoporosis is a silent disease. You might not know you have it until you break a bone. A bone mineral density test is the best way to check your bone health.
To keep bones strong, eat a diet rich in calcium and vitamin D, exercise, and do not smoke. If needed, medicines can also help. It is also important to try to avoid falling down. Falls are the number one cause of fractures in older adults.
Vitamin D
Vitamins are substances that your body needs to grow and develop normally. Vitamin D helps your body absorb calcium. Calcium is one of the main building blocks of bone. A lack of vitamin D can lead to bone diseases such as osteoporosis or rickets. Vitamin D also has a role in your nerve, muscle, and immune systems.
You can get vitamin D in three ways:
through your skin, from your diet, and from supplements.
Your body forms vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer. So many people try to get their vitamin D from other sources.
Vitamin D-rich foods include egg yolks, saltwater fish, and liver. Some other foods, like milk and cereal, often have added vitamin D.
You can also take vitamin D supplements. Check with your health care provider to see how much you should take. People who might need extra vitamin D include:
* Seniors
* Breastfed infants
* People with dark skin
* People with certain conditions, such as liver diseases, cystic fibrosis and Crohn’s disease
* People who have obesity or have had gastric bypass surgery
- Published in Blog, supplements
Protein: A harmful or beneficial nutrient for bone
High protein intakes are considered essential to support the demands of training, and as such, athletes are recommended to consume more protein (between 1.2 and 1.6 g/kg/day, with up to 2.2 g/kg/day considered useful in some situations) than the general population (currently 0.8 g/kg/day). At the same time, there is a long held belief that higher protein intakes may actually have a negative influence on bone health. This is based on the “acid-ash hypothesis”, which suggests that animal proteins are acidic, and so can disrupt body pH. A balanced pH is essential for function of all body cells, and so the body will counterbalance an acidic state by increasing the availability of alkaline minerals, so normalising pH. The problem is, that most of the bodies alkaline minerals (e.g.,calcium) are stored within the bone. A chronic need to normalise pH in response to habitually high protein intakes, can, in the long term, result in bone mineral loss and weakening. Supporting this hypothesis is evidence that diets with a high potential renal acid load (PRAL), namely those high in animal proteins, are associated with a greater loss of calcium in the urine. This may be associated with lower bone mineral density, and an increased rate of bone loss.
The acid-ash hypothesis does have some possible merit, but it also describes just one of the pathways through which high protein intakes may theoretically influence bone, and is by no means the full story. For a start, the acid-ash hypothesis assumes that the calcium lost in the urine when protein intakes are high, comes from the bone. It seems, however, that higher protein intakes actually increase the amount of calcium that is absorbed from foods, and the increased calcium found in the urine when protein intake is high comes from this increase in calcium availability, and not from the bone, as was originally assumed.
Another important point, is that calculations of dietary acid load, are not only influenced by a high intake of acidic foods, but also by a low intake of alkaline foods. Most alkaline foods (e.g.,fruits and vegetables) are also rich in a wide range of micro- and phyto-nutrients that are essential to bone health. It is possible, therefore, that the poorer bone outcomes reported in individuals who consumed an acidic diet, were not actually due to high protein, but to a shortage of nutrient rich fruits and vegetables.
More importantly, evidence exists to show that not only is protein not harmful to bone, it can actually be beneficial. Bone tissue is made up of ~50% protein, which makes it essential that athletes consume sufficient protein to support the increased rate of bone turnover caused by athletic training. Additionally, protein ingestion is known to increase the production of a number of hormones and growth factors, such as IGF-1, which are also involved in the formation of bone. Perhaps most importantly, the physical loads caused by exercise training are recognised as the main determinant of bone. Athletes in high-impact sports are frequently reported to have stronger bones that non-athletes. These loads come from a combination of both gravitational and muscular forces. It follows, therefore, that if higher protein intake positively impacts muscle mass function, and the capacity to undertake exercise training, it should also positively influence bone.
Considering all of these factors, it seems paradoxical to believe that higher protein intakes could really harm bone. Ultimately, the only way to determine the net influence of protein intake on bone, is to examine original studies that investigate this. A large number of these types of studies have been conducted, and the results have subsequently been statistically combined in high-quality meta-analyses [5]. Considering all available evidence, the answer is clear: Provided calcium intake is adequate, there is no evidence to indicate a negative influence of protein on bone, and instead a positive, albeit small, effect on bone mineral density and fracture risk has been identified. And so, the consensus is that protein is an essential nutrient, not only for muscle, but also for bone.
- Published in Blog, Nutrition, supplements