By Dr. Peter Kadile

Hello Dr. Kadile, what is the difference between a cold and the flu?
-John, Desert Hot Springs

John, a cold is a milder respiratory illness when compared to the flu. A cold typically starts out with a sore throat and then leads to sinus congestion, runny nose, sneezing and a cough. Fevers rarely occur in a cold. Of course you just don’t feel good with a cold, but a cold will generally resolve in less than a week. The flu may make you feel quite ill for a few days to weeks. Flu symptoms generally develop quite quickly and can manifest with severe sore throat, fevers, headaches/body aches, congestion, cough, nausea/vomiting and diarrhea.

A cold and the flu are caused by viruses, not bacteria, thus they will not respond to antibiotics, so don’t go running to the urgent care for a Zpack. In severe cases of the flu, a secondary bacterial pneumonia may develop that would require the use of antibiotics.

Dr. Kadile, why all the hype about taking extra vitamin D, when everyone can get it from sunlight?
-Sally, Palm Springs

Sally, your body does make its own vitamin D from sunlight. Exposing your bare skin is the best way for your body to produce the vitamin. But, if you wear sunscreen or keep yourself covered with a hat or long sleeves or pants, you may not have adequate exposure to produce vitamin D. The same goes for people who live in areas where it is mostly cloudy or overcast. So if you don’t get enough, then you will need to supplement. You can get vitamin D from over the counter supplements and a very small amount comes from diet.


Vitamin D is important for good overall health and strong and healthy bones. It is also important in making sure your muscles, hearts, lungs and brain work well and that your body can fight infection. It may even have some anti-cancer effects. With cold and flu season just around the corner, optimal vitamin D levels are crucial in preventing these illnesses.

Vitamin D deficiency has been linked to cancer, asthma, diabetes type 2, high blood pressure, depression, Alzheimer’s, multiple sclerosis and Crohn’s disease.

I have been routinely checking my patient’s vitamin D levels with a simple blood test for the past 6 years and I am no longer surprised to find that a majority of my patients are vitamin D deficient. You would think that since our desert climate is mostly sunny for the majority of the year, vitamin D deficiency would be rare, but it is not. We spend most of our time indoors and you can’t absorb the sunlight through a window. We have also been taught to wear sunscreen to protect against skin cancer if we spend a lot of time outdoors.

So, if you would like to know if you have enough vitamin D, ask your doctor to order a simple lab test (called the vitamin D, 25 – hydroxy level). If you don’t spend enough time outside, you can supplement with vitamin D3 to achieve optimum vitamin D levels. Different organizations recommend different daily intakes of vitamin D, so work with your doctor in determining which dose to start with depending on your lab results.

Dr. Kadile, what is the difference between vitamin D and vitamin D3?
-Charlie, La Quinta

Well Charlie, if the supplement simply says, “Vitamin D”, you will have to look closer at the label to see if it specifies either vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol).

There is a difference between vitamin D2 and vitamin D3.Vitamin D2 is manufactured by plants or fungus and is fortified in foods, such as juices, milk or cereals. Vitamin D3 is the form of vitamin D that is produced when the body’s skin is exposed to sunlight. Vitamin D3 is considered the more ‘natural form” of vitamin D. It can also be obtained when eating animal products. Vitamin D3 is more potent than D2. Vitamin D3 has been shown to raise and maintain serum D levels greater than vitamin D2. Clearly vitamin D3 is the preferable form of vitamin D.