Does vitamin D have any positive direct effect on the immune system?   That's the question we seek to answer this week on Life By Design.   We are using direct to mean, if you take Vitamin D, is there any data pointing out that you may have a decreased chance of contracting the flu?   There is already data and professional hypotheses on how people with "pre-existing" autoimmune diseases have an increased risk of developing the full-blown autoimmune disease if they are Vitamin D deficient.   This week we present a study, and randomized controlled trial, from Japan. The researchers followed school-aged children through flu season (December - March), giving half of the 340 student sample size Vitamin D while the other half received the placebo.    What We Cover

• The study, it's results, a general discussion, and what those results could mean for you and your family's health.
• Why we think you should be taking Vitamin D...don't think the real reason is the avoidance of disease. Avoiding disease only gets you to zero; we're hoping you can be so much more than just that.
• We don't guess we test - how much Vitamin D should you be taking, despite the conflicting data and how you know you're taking enough?
• What are the best sources for Vitamin D and how to get it.
• The difference between a food and a supplement and why it's important to know the difference.