Vitamin D has been the “it” supplement for a while and I have to admit, I am a believer. Here are the top 10 things I think everyone should know about vitamin D, in order to make an informed decision about optimizing vitamin D intake in yourself or your children.

More than just bone health. We all know that Vitamin D is good for bone health. However, it is also involved in many other functions, mainly related to your immune system, cell growth and gene expression (turning on and off genes in your body—something you want your body to get right). Though randomized, controlled studies are lacking, there is a good amount of data linking low levels of vitamin D to various diseases, including breast cancer, colon cancer, multiple sclerosis and type 1 diabetes.

Your doctor may care about your vitamin D level. I certainly do! Many doctors, including me, like to ensure sufficient vitamin D levels in at-risk patients. For example, if I have a mom with multiple sclerosis, I make sure she is on top of her children’s vitamin D intake. Patients with non-specific symptoms, symptoms that don’t immediately lead to a specific diagnosis (like fatigue, for example), may also benefit from treating vitamin D deficiency or insufficiency, to optimize overall health. Vitamin D levels can be measured through a blood test.

Sources. Vitamin D comes mainly from 4 sources.

• Foods like fatty fish and organ meats (…but apart from Tony Bourdain, who eats liver anyway?)
• Fortified products, like milk
• Supplements (pick D3 over D2—see more below)
• The sun

• A cup of milk provides  about 100 iu vitamin D
• 4-ounces of salmon contains 600 iu vitamin D

So if you are a family that eats fatty fish 3 times a week and drinks a few glasses of milk a day, you probably don’t need any additional vitamin D. If your kid hates fish but drinks about a cup of milk a day and has a serving of a fortified yogurt, I would recommend a 400 iu daily supplement.

Be wary of the very high dose supplements — there are risks to overdosing! But rest assured, it is very unlikely to overdose if you are ingesting recommended daily intakes.

Vitamin D does NOT occur naturally in milk. Milk is fortified with vitamin D. Thus, products of milk, like yogurt, cheese and cottage cheese, are not good sources of vitamin D unless they are also specifically fortified. Some brands of yogurt are fortified, so you need to check your labels. Just to contrast, calcium exists naturally in milk, so all dairy products are good sources of calcium.

Which form of vitamin D should you take? If you are taking a vitamin D supplement, take vitamin D3 (also known as cholecalciferol) since it is probably better utilized by your body as compared to vitamin D2 (ergocalciferol). Also, take it with a meal. Vitamin D is likely better absorbed with a nice, big meal.

Which drops? If you are using vitamin D drops for your baby, read the label. There are definitely some superior options. First off, your baby does not need the other vitamins, like A and C that are found in Poly-vi-sol or Tri-vi-sol. Such products may also contain artificial colors and flavors—again, unnecessary additives. Additionally, you may seek a formulation that offers smaller volumes. For example there are brands, like Carlson’s, that contain 400 iu of vitamin D in just one drop, as opposed to an entire 1 mL dropperful. The drop can be placed on your finger, pacifier or nipple. Again, this should be in the form of vitamin D3, or cholecalciferol.

Are vitamins safe? Like all supplements, your vitamin D is not FDA approved prior to going on the market. Supplements are considered innocent until proven guilty. That is, only if a concern becomes obvious does the FDA intervene. Hence all the weight loss products on the market that don’t get pulled until multiple people start dropping from heart attacks.

How much sun is enough? We just do not know. It varies from person-to-person, location and your definition of “sufficient.” UV-B rays from the sun help your body synthesize vitamin D. However, in the winter, especially in higher latitudes, there is not that much UV-B out there. AND, I would like you to wear sunscreen (especially to protect precious baby and child skin!) which blocks UV-B ray absorption.

Skin color makes a difference. People with darker skin have a harder time absorbing UV-B from the sun and making vitamin D. If you are darker skinned, you may need more vitamin D than you think.

Another reason to lose weight. Obese people have a harder time absorbing vitamin D. Some medications and certain conditions that affect gastrointestinal absorption may also affect your vitamin D requirement.

Ok, so those of you paying attention realized these are actually my top 11 things to know about vitamin D.

Look out for my next post– I think it is going to be, “Should I go organic?”