Is it better to have soft or hard bones?

Generally speaking, when we are younger, our bones are not fully developed and are therefore very soft and fragile, but as we age, our bones begin to become hard. So, some people will have the question: Is it better to have soft bones or hard bones? In fact, for adults, if they are not engaged in dancing or acrobatics, it is better to have harder bones.

Bone tissue is made up of a mixture of living cells and minerals (mainly calcium and phosphorus), which give bones their solid physical properties.

Bones come in different shapes and sizes, for example, arm bones are long bones, wrist bones are short bones, the sternum and skull are flat bones, and vertebrae are irregular bones. The bones of adults are mainly composed of two types of tissues: hard compact bone on the outside and porous cancellous bone, also known as spongy bone, on the inside. The thigh bone, or femur, is filled with fat called yellow marrow.

The bones are constantly renewed and are renewed every day. Calculated in terms of calcium, an adult needs to renew about 700 mg of calcium every day, which is equivalent to 3-5% of bones dissolving every day. Another 3-5% of new bone is formed.

The main component of bones is calcium carbonate. The average calcium content in an adult's body is 1000 to 1250 grams, 99% of which is concentrated in bones and teeth, and the remaining 1% of calcium exists in cells, extracellular fluid and blood, which is called miscible calcium. There is a state of mutual transformation between the calcium in the bones and the soluble calcium outside the bones. That is, the calcium in the bones is constantly dissolving into soluble calcium, and at the same time, the soluble calcium is constantly deposited into bones. In this process of dissolving bones and forming bones at the same time, if the amount of calcium dissolved is equal to the amount of calcium deposited, it is called a balanced state. If more calcium dissolves and less calcium is deposited in the same period of time, osteoporosis will occur.

The length of human bones generally stabilizes at around the age of eighteen, which means they will no longer grow taller. However, bone density continues to increase. After the age of 40, bone density begins to show a downward trend. The speed of descent depends on the person's physical condition. Generally, people who are physically active or like sports progress more slowly.

Calcium in the human body mainly comes from food. Many foods are rich in calcium. However, most of the calcium in food cannot be absorbed. Adults can only absorb about 20%, and about 80% of the calcium just makes a trip through the human body and is excreted.

Why is the calcium absorption rate so low? There are many reasons for this. The first is the effect of vitamin D on absorption. The special ability of vitamin D is that it can promote the small intestine to absorb calcium and phosphorus, increase the calcium and phosphorus content in the blood, and promote bone renewal. When vitamin D is deficient, calcium absorption is reduced. In addition, other ingredients in food can also affect calcium absorption. For example, many vegetables contain oxalic acid, which can react with calcium to form insoluble calcium oxalate. Insoluble precipitates cannot be absorbed and can only be excreted. Common vegetables, such as spinach and amaranth, contain more oxalic acid. 100g of fresh spinach contains 606mg of oxalic acid, while 100g of fresh amaranth contains even more oxalic acid, up to 1142mg. If you put tofu and spinach, which are very rich in calcium, together to make soup, the calcium in the tofu will be greatly lost before entering the human body. People who are calcium deficient should eat less spinach and amaranth. In addition to vegetables, cereal grains also contain more oxalic acid, which will react to form insoluble calcium compounds and affect calcium absorption. Furthermore, age also matters. Infants can absorb more than 50% of the calcium in food, children absorb about 40%, and adults absorb about 20%. For adults over 40 years old, the calcium absorption rate decreases by 5 to 10% every 10 years on average. The bones of the elderly gradually become porous.