I'm a Life Extension member and I get most of my supplements from them and they recommend 5000 iu's in months when you have most of your clothing on. Your skin makes vitamin d when exposed to sunlight so in the summer u really don't need to supplement with it. January and February being the worst months I take more.
Not too long ago I was diagnosed with a rare form of cancer; during the testing I was found to be seriously Vitamin D deficient. Upon the completion of the chemotherapy and radiation treatments, I was prescribed 50,000mg of Vitamin D to be taken once weekly (Yes, it was a big pill). As my levels increased, I was than recommended to take the over the counter supplement D3 Extreme (which was 2000mg daily).
During that time I never got sick, no bronchitis (which I would get from time to time), no runny nose or scratchy throat (even when everyone else in the house was sick), even the debilitating migraines I would get were drastically reduced. I ignorantly rationed that the chemo and radiation treatments must have boosted my immunities, or the chemo was still lingering in my system destroying any germ that dared entered my body. Never once making the Vitamin D connections until NOW!!!!!
Today, I no longer take any Vitamin D supplements and I am still considered Vitamin D deficient, because taking such large amounts of it leads to some very unpleasant side effects; mainly Kidney Stones.
For those of you who have never experienced them, you cannot imagine the pain. Passing them manually can be a long and excruciating ordeal but having the lithotripsy (breaking them up through sound waves) procedure done is 100x worse. It’s like someone kicking you in the balls for two hours straight. I have stopped taken the Vitamin D almost 3 years ago and have not gotten a kidney stone since, so draw your own conclusions.
Be very careful with any supplement you might take, and be even more careful with any drugs your doctor may prescribe. Many of today’s Doctors are nothing more than “Billers” who prescribe drugs for “borderline” ailments just to increase your visits or from kickbacks that drug companies might offer. I know we’re a long way from the dark ages, but listen to the possible side effects to many of these drugs advertised on TV, and ask yourself if your ailment is worse than possibly getting these side effects.
As for the flu, the flu kills 400,000+ people worldwide each year, why be one of them? The flu can be especially dangerous when added with another know (or unknown) ailment, like asthma. I have had the flu twice in my life, and like Genius said, it is not pleasant. When people ask me about chemo, I tell them except for the initial treatment (which I thought was going to kill me), my bouts with the flu were much worse.