Be sure to consider the source when taking this supplement. Vitamin D2 is a synthetic form (used for food fortification), which I would not take. Vitamin D3, which is consider the natural form, is found in foods such as egg yolks and liver and products like Cod Liver oil. This is also the form that is produced in the body as a result of sun exposure.
Unfortunately if you live above the 37th latitude, you will not be able to get enough sunlight during the winter months (November - March). In this case, you may want to consider supplementation. Honestly, I hate taking supplements! I would much rather get what I need from good food! Yet, I realize that is necessary sometimes. For my family, I will supplement with Vitamin D if I see a need for it (i.e. ongoing illness). Fortunately we are rarely sick.
The very VERY best thing you can do for your health (and Vitamin D levels) is make going outside a habit! It is such a simple way to improve your health, yet so many people overlook it! We have developed a cultural trend of living, working, and even playing indoors. This has contributed to a society that is very Vitamin D deficient! It is estimated that 85% of the American public are deficient! If you can expose yourself to the sun at least 3 times per week for 15 minutes, you can supply your body with an adequate amount of Vitamin D. By being outside in the winter months, you will be getting fresh air and most likely exercise, two more contributors to good health.
Another factor contributing to deficiencies is fear. Doctors have convinced people that they should be afraid of the sun. Therefore we either don't go outside or worse, we cover ourselves in sunscreen. Please do not put sunscreen on your children! Be a responsible parent and make sure your children do not burn, but let them get sun exposure. Just as we have a spiritual need for the Son, our bodies were also created with a physical need for the sun. Our family spends time outside almost every day of the year. In the spring, summer, and fall we spent LOTS of time outdoors, and it is rare for us to get sunburned. In the beginning of the summer, if a child looks a little pink, I make them wear a wide brimmed hat and have them avoid tank tops. Gradually we build up a tan, and then we are set for the rest of the summer. Our family never uses commercial sunscreen! A natural option for sunscreen is coconut oil, which we have used on occasion. The point is, you do not have to be afraid of the sun! You need it, so go outside and enjoy it! :)