Are you getting the right vitamin D?

Author: Chen Qian Children's Hospital Affiliated to Chongqing Medical University

Reviewer: Cheng Qian Professor of Children's Hospital Affiliated to Chongqing Medical University

Zhang Xuan, Associate Professor, Children's Hospital Affiliated to Chongqing Medical University

All mothers will encounter a common problem. The doctor said that children should take vitamin D or cod liver oil. So what is the difference between vitamin D and cod liver oil? How to choose? Although there are many popular science articles related to this, they are just like the brands of cod liver oil, which are varied. Add in various advertisements and rumors, and mothers are even more confused. Some people will say that I can always buy the most expensive one. I don’t know the value of money, but I know the value of goods! In fact, buying expensive things does not necessarily mean eating right.

Why take vitamin D supplements?

It is generally known that breast milk is the best food for babies. But in fact, the vitamin D content in breast milk is extremely low (12-60 IU/L), and other natural foods, including milk, also have low content. Currently, a large number of studies have found that vitamin D is very important to the human body (not just to promote calcium absorption), and nature has set the main source of this important vitamin as "skin light synthesis".

However, many factors affect the amount of vitamin D synthesized by the body (such as skin color, obesity, skin exposure, environmental pollution, latitude, genetic factors, etc.). As people's living habits and environment change, the time spent outdoors is limited every day, and the body cannot synthesize enough vitamin D. Therefore, vitamin D deficiency is becoming more and more common, and vitamin D supplementation is very necessary.

How much should I take every day?

my country's latest dietary guidelines in 2013 recommend that the preventive dose of vitamin D is 400-800 IU/d. The 2016 edition of the Global Consensus on the Prevention and Management of Nutritional Rickets states that 400 IU/day (10 μg/day) of vitamin D is sufficient to prevent rickets. It is recommended that infants aged 0-12 months should reach this level regardless of the feeding method. Infants, children and adults over 12 months old should reach the level recommended by the National Institute of Medicine (IOM) of the United States through diet and/or supplements, which is at least 600 IU/day (15 μg). In my country, the choice can be made based on different conditions such as north or south, winter or summer, and degree of sunshine.

It is worth noting that the supplement dosage for premature infants, twins, and low birth weight infants will be different, and the specific supplement dosage needs to be consulted with a doctor in a timely manner.

Can I overdose on vitamin D if I buy it from a pharmacy?

No poisoning. In fact, even if you get sun exposure every day and supplement 400-800IU of vitamin D, the human body will not be poisoned: first, the toxic dose is not reached; second, our body is very smart. When there is enough vitamin D in the body, even if there is a lot of sun exposure, the amount of vitamin D synthesized by the skin is reduced, ensuring the absolute safety of the body. Therefore, the vitamin D with a drug approval number is appropriate and safe.

Will taking vitamin A cause precocious puberty?

It will not cause precocious puberty. Vitamin A is also an important vitamin necessary for the human body, and the content of vitamin A in breast milk is low. Foods rich in vitamin A include "animal liver, milk, fish, seafood, cream and eggs". The World Health Organization defines my country as a country with moderate vitamin A deficiency. Surveys show that vitamin A deficiency in the Chinese population is a common phenomenon. Therefore, it is recommended to supplement vitamin A and vitamin D at the same time. The recommended dose of vitamin A for infants under six months old is 300μgRAE (microgram retinol equivalent)/day (about 990IU), and 350μgRAE/day (about 1155IU) for infants from six months to one year old. The toxic dose of vitamin A is relatively large, and it is safe to take less than 2000IU per day within one year old. Therefore, the vitamin A in most drug approval numbers is appropriate. As long as you take it according to the doctor's advice, there is no situation of over-supplementation. In addition, no research has shown that vitamin A is related to precocious puberty. Therefore, regardless of whether the dose is appropriate, vitamin A supplementation will not cause precocious puberty.

On the other hand, if a child's diet is basically the same as that of an adult, and if they can ensure sufficient food sources, such as eating seafood every week and consuming sufficient amounts of foods rich in vitamin A on a regular basis, they do not need to take additional vitamin A supplements.

How to calculate the vitamin dosage contained in cod liver oil and how to choose it.

The term cod liver oil is now being abused. In the past, cod liver oil generally referred to vitamin AD, but since when, it seems to have become a general term for oily multivitamins or nutrients. Non-professionals will call vitamin D, vitamin AD, DHA, and multinutrients (even including vitamin E and calcium, magnesium, and zinc) cod liver oil.

How can you learn to read the dosage of vitamins yourself? Please remember that the total vitamin D content you take in every day should be between 400 and 800 IU, or 10 to 20 μg. It should be noted that if the brand contains the words "cod liver oil", please remember to calculate it, as most of the content is not enough. For example, the ingredient list of a certain brand of fish oil:

Figure 1 Copyright image, no permission to reprint

The vitamin D content is 0.75μg, equivalent to 30IU, which is only about 1/13 of the recommended dose; the vitamin A content is 100μg, equivalent to 333IU, which is about 1/3 of the recommended dose. Therefore, the vitamin content of this cod liver oil is insufficient.

If it is a cod liver oil that does not indicate the dosage of each capsule, as shown in the picture below.

Figure 2 Copyright image, no permission to reprint

Each capsule weighs 0.5g, that is, every 200 capsules contain 666μg of vitamin D, and each capsule contains 3.33μg of vitamin D = 133IU. Even though the vitamin content of this cod liver oil is higher than the previous example, it is still not enough for breastfed babies. It should be noted that there is no research to prove that expensive cod liver oil is definitely better than cheap ones, nor does it say that cod liver oil extracted from cod is better absorbed than other sources. Therefore, we need to pay more attention to whether the dosage is appropriate. When parents buy cod liver oil, as long as the product contains the right amount of vitamin D and the purchase channel is regular, they don’t need to pay much attention to the choice of brand.

How long should I take vitamin D?

This is because children nowadays lack outdoor places for activities; early childhood education,

The time for outdoor activities has been reduced, and when doing outdoor activities, they rarely get sun exposure, so children after the age of 2 do not actually get much sun exposure. Therefore, it is now recommended that vitamin D supplementation needs to continue until adolescence. Of course, this also varies from time to time, from place to place, and from person to person. Some babies do outdoor activities in sunny and mild places every day, and do not apply sunscreen. These people basically do not need additional supplements. However, the amount of sun exposure time needs to be appropriate, and excessive sun exposure may increase the incidence of skin cancer. However, in some areas, such as Chongqing in winter, the probability of sunshine is low, the sunshine time is short, and children's skin is not exposed much in winter, especially children who are already in elementary school, who have even less sun exposure time. These children should be supplemented.

Figure 3 Copyright image, no permission to reprint

How much sun exposure time is enough?

There is no very accurate answer at present. This is because it is related to the exposed skin area, skin color, age and the intensity of ultraviolet rays in sunlight. So to be on the safe side, please remember to supplement vitamin D. If you are still not sure, please take the cod liver oil or vitamin D preparation in your hand and consult the pediatrician.