Spring is here and everything is recovering. This is also the golden period of growth in the year that everyone often talks about.
Do children really grow faster in spring?
Past research suggests that there may be such a thing, but why does it grow faster?
From 1886 to 1971, some studies on the growth of school-age children in the northern hemisphere showed that the fastest growth of children's height was in spring or summer, and the fastest growth of weight usually occurred in autumn or early winter.
In the 1990s, a small study in Sweden also found that the average growth rate of 50 children aged 7 to 10 in autumn was 5.06 cm/year, which was significantly lower than the 8.15 cm/year in spring.
In addition, some researchers have found that children who are treated for growth hormone deficiency, although they use the same dose of growth hormone throughout the year, also show a faster growth rate in the spring and early summer.
In 2020, another interesting study found that the growth and development of babies also have a certain seasonality. The study compared the growth and development data of 9,409 infants in Japan from 2014 to 2017. After using statistical methods to exclude the effects of age, gender, nutrition and birth month, it was found that the infants grew significantly faster in summer than in other seasons.
The baby of 6 months grows 13% faster in summer than in winter. But this study did not find any seasonal changes in body weight.
However, some studies have found that the seasonal changes in children's growth are not obvious. For example, a study conducted among Japanese elementary school students from 1982 to 1984 did not observe seasonal changes in height and weight gain.
If we want to help children grow taller, we must first know why children grow faster in spring and summer.
01 Why is it easier to grow taller in spring and summer?
The specific reason is still unclear, and it seems to be independent of temperature. The researchers guessed: It may be related to the length of the day.
Interestingly, the total height throughout the year has nothing to do with the latitude of the living area, because people of different dimensions have the same total daytime throughout the year.
Growth and development seem to accelerate in the season with long days, and slow down in the season with long nights. However, high latitudes have longer days in summer, but shorter days in winter, while the total daytime in areas of different latitudes is basically the same throughout the year.
The effect of the number of hours during the day on the growth rate of height
In high latitudes, summer days are very long, and the growth rate of children in summer is very fast, much faster than in winter. But they grow faster in summer, and grow much slower in winter.
In low latitudes, the difference in growth rate between winter and summer is very small, and there is no such thing as a "spring increase".
In other words, the total growth of the child throughout the year has been "programmed". It grows very fast in spring and summer, and grows very slowly in autumn and winter.
Although the children's height increases at different rates in different seasons. Height growth is faster in spring and summer, but the total height growth in a year is determined by genes, nutrition and the health of the child. I am afraid that seasonal changes do not make the child taller, but just show that the child’s development is not uniform.
02 Growth speed is related to lifestyle in different seasons
Some researchers have pointed out that this seasonal change in growth may be directly or indirectly related to its adjustment and lifestyle in different seasons.
For example, sun exposure may affect the secretion of hormones such as melatonin, insulin-like growth factors, leptin, and ghrelin that can regulate growth and body weight.
Meteorological conditions may indirectly affect the growth and development of children in terms of food supply, infectious diseases, and physical exercise.
In addition to genes, nutrition and disease are important factors that affect height. From these two perspectives, compared to the cold winter, the warmer spring may really help the child to grow taller.
Like the common cold, flu, and other respiratory diseases are also more likely to occur in winter. On the one hand, people tend to stay indoors with poor air circulation, which makes it easier for the virus to spread. On the other hand, cold, dry air may also reduce the resistance of the body's respiratory tract. And illness can also affect the child's development. In addition to affecting the child's appetite, it may also affect the child's hormone level.
Hormones are substances that transmit signals between body systems. They affect all aspects of our health, from growth and development and metabolism, to blood pressure and mood. Almost all hormones can affect growth to some extent, but some of them have more important effects, such as growth hormone, thyroid hormone, cortisol, insulin, androgen, testosterone, estrogen, estradiol and so on.
In fact, the results of the study reflect the general situation of the group. Because the specific situation of each child is different, it doesn’t mean that all children grow slower in winter than in spring.
If it is really the "spring increase" determined by factors such as nutrition, disease, exercise, sunshine, etc., then if you can ensure a balanced and adequate nutrition in winter (this is the most important), encourage your children to exercise (reduce sickness), reduce stress and sleep well(ensure that the child is energetic), get vaccinated on time (to reduce the probability of major diseases), the child can also achieve good growth and development in winter!
03 Do the children need calcium supplements if we want them grow taller？
Calcium is a basic element necessary for the human body, and it is also a nutrient element which closely related to bone health and the promotion of height. However, it should be emphasized that the main factor related to height is the overall nutritional status of the child. Supplementing a certain nutrient alone is difficult to achieve the effect of growing taller.
There are many nutritional supplements on the market that claim to help grow taller, such as calcium supplements. Studies have found that calcium supplementation to mothers before the baby is born (which will not increase the length of the newborn), or calcium supplementation after the baby is born or during childhood, has no effect on the height of the child.
If there is a lack of calcium, there will be no performance in the short term (unless severe malnutrition). The effect of calcium deficiency is often osteoporosis, which is manifested as easy fracture.
Calcium nutrition needs to accumulate over the years, all the "low bone density" in childhood is what it should be, as long as you eat well and slowly "accumulate" will be fine. Calcium saving is done, especially when it comes to old age, it will show results. Building strong bones in childhood can reduce the risk of osteoporosis in old age. According to the report of the International Osteoporosis Foundation, every 10% increase in peak bone density can delay the occurrence of osteoporosis by about 13 years.
To supplement calcium, we must focus on food supplements.
Milk is the most abundant calcium source, the easiest to absorb, and the most convenient source of calcium. A cup of 240 milliliters of milk contains about 300 mg of calcium. Yogurt and cheese are also rich in calcium. Children of every age group over one year old should be encouraged to drink more milk.
If you have lactose intolerance, you can drink milk in small amounts and many times, or you can choose to eat more yogurt and cheese. During the fermentation process of these two, almost all lactose is decomposed, and there is no need for the human body to digest lactose, so it is especially suitable for people with lactose intolerance.
For children who have to avoid milk or dairy products due to milk protein allergies or other reasons, calcium can also be obtained through other foods. Some green vegetables with low oxalate, such as broccoli, Chinese cabbage leaves, cabbage, kale, and fruit juices with calcium citrate are good and easy to absorb calcium sources.
And some foods high in oxalate, such as spinach, green beans, etc., or some foods high in phytic acid, such as plant seeds, dried fruits, grains, etc., the calcium contained in it is not easy to absorb. Compared with milk, the bioavailability of calcium in dried beans is only half that of milk, while the bioavailability of calcium in spinach is only 10% of milk.
Sardines, salmon, and bivalve shellfish (such as scallops, oysters, etc.) also have higher calcium content.
A balanced diet helps calcium absorption. It should be noted that if the protein and sodium (salt) content in food is too much, it will promote the excretion of calcium by the kidneys.
If you do not eat dairy products, do not eat broccoli, cabbage, kale, do not eat beans and soy products, do not eat sardines, salmon and shellfish... And if you do need calcium supplements, calcium citrate and Calcium carbonate is a good choice. Calcium citrate does not require the participation of stomach acid to help digestion and absorption. It can be taken at any time. Calcium carbonate is best taken with meals to help absorption and reduce gastrointestinal discomfort.
The calcium content of milk calcium and calcium gluconate is usually not very high... Why do children use them? The main consideration is that some younger children can't swallow calcium tablets, so they are made into "liquid calcium"; in addition, children really don't need to "supplement" calcium...
Although calcium supplementation has not been found to be related to height, researchers have found that there is a type of high-calcium food that may be related to height, which is dairy products.
04 The intake of dairy products may be related to height
A study conducted by Dr. Catherine Berkey of Harvard University and others found that the protein in dairy products may be particularly important for helping to grow taller. The study followed up more than 5,000 girls (80% of them were followed for at least 6 years) and finally found that their adult height was positively correlated with their adolescent dairy intake, that is, those girls who ate more dairy products. The average height in adulthood is higher.
Further statistical analysis of nutritional elements in food and height found that the protein in dairy products has the closest relationship with height, but the study did not find any relationship between animal or plant protein and height.
Another small sample study conducted in New Zealand also found that compared with children who drank milk regularly, children who had less long-term milk intake were shorter.
05 Why does calcium supplementation have little effect on growth, but the opposite is true for dairy products?
The reason may be that dairy products are rich in many nutrients that are beneficial to the growth of children, such as high-quality protein, calcium, iron, vitamin A, B vitamins, niacin, and vitamin C.
With only one's own power, the nutrition that children need for growth can be met to a large extent. This is why, in the diet of young children, dairy products and starchy foods, protein foods, fruits and vegetables are juxtaposed, occupying a very important position.
The effect of protein on height
Protein is an important component of all cells and tissues of the human body and participates in every process of cell life activities. It provides the body with a source of amino acids, which are essential nutrients for the formation of bones.
The quality and quantity of protein in the diet are inseparable from the growth and development of children and adolescents. The protein and amount in dairy foods are very high.
Foods rich in protein include
- Dairy products, such as milk, yogurt, cheese
- Lean meat, fish and poultry
- Beans and legumes, such as lentils, chickpeas
- Soy products, such as tofu, soy milk
- Some grains and cereal products
The effect of zinc on height
Zinc is a basic trace element necessary to maintain intestinal cells, bone growth and immune function. If a child is severely deficient in zinc, it may change the metabolism of growth hormone, leading to developmental arrest. Severe zinc deficiency can also cause immune damage, skin diseases, learning disabilities and anorexia.
The causes of zinc deficiency include insufficient intake of zinc-containing foods or insufficient zinc absorption. Most foods with high zinc content are animal-derived foods, such as meat, eggs, and seafood. In addition, nuts and beans are good sources of zinc. Nowadays, it is basically not a problem for children to get enough zinc from food, so severe zinc deficiency should be rare, but borderline zinc deficiency is possible. If the child has frequent gastrointestinal infections (gastroenteritis) or allergies and other reasons, frequent diarrhea can also further deplete the body's zinc reserves.
The absorption of zinc is also affected by other food ingredients. Protein in food is an important factor affecting zinc absorption. Small changes in protein digestion can also have a big impact on zinc absorption. In general, the intake of foods high in animal protein (such as meat and dairy products) will make zinc absorption better than foods high in plant protein.
06 Don't ignore the vitamins related to the season
Everyone generally pays attention to calcium, and even pays too much attention to calcium nutrition. In addition to calcium, vitamin D also plays an important role in building and maintaining bones.
Although vitamin D is called a vitamin, strictly speaking, it is not a vitamin, but a hormone that can promote the absorption of calcium in the body. Because vitamin D is indispensable for the normal development of bones, it can ensure normal bone renewal and bone mineralization. Long-term lack of vitamin D in children can lead to developmental delays and skeletal deformities, commonly known as "Rickets".
In recent years, some studies have also found that once vitamin D is lacking in the body, it will affect not only calcium-related functions, but also the body's immune system function.
Vitamin D is produced when the skin is exposed to ultraviolet rays from the sun. However, factors such as season (winter) and latitude (high latitude), use of sunscreen, smoke in the air, skin pigmentation, age (elderly) and other factors will affect the amount of vitamin D produced by the skin through sun exposure.
This goes back to what we mentioned at the beginning of the article. It is easy to get sick in winter, vitamin D is easy to lack in winter, and height is relatively low in winter... These phenomena may be inextricably linked.
Food sources of vitamin D include: egg yolk, animal liver, butter and dairy products. The oil extracted from the liver of fish (especially cod), and oily fish (such as herring, mackerel, salmon, sardine, eel, tuna, etc.) are rich in vitamin D.
Food sources of vitamin D are relatively few, and the climate and latitude of some areas objectively make people unable to obtain sufficient vitamin D, or when there is little outdoor activity and sun exposure in winter, supplements should be considered.
Although the reason for the increase in spring is not very clear, based on the available evidence, we can speculate that "seasonal changes in height" are related to climate, diet, and lifestyle.
It is unrealistic for everyone to increase calcium supplementation in the spring, but ensuring a balanced nutrition for children, especially adequate intake of dairy products, may be meaningful for height growth.
Regardless of the season, we should provide children with sufficient nutrition as much as possible and encourage them to do more outdoor sports.
So, starting from this spring, let us go out more, exercise more, eat a variety of foods, and make sure that each of us drinks 1-2 cups of milk every day!
Recommended milk volume:
- Toddlers 1-2 cups (300-500ml),
- 2 cups (500ml) for children, adolescents, adults and the elderly
- 3 cups of puberty (750ml)