Best1West - If you have still got low levels of vitamin D , even after taking sufficent supplement ,then you may need to change your strategy. BUT , bear in mind that we humans have a very different response to supplementation. Some peole when taking 1000 I.U , daily will only raise their level a little bit . On average 1000IU daily will raise your level by 25 . Some people only half that, some people double that. It depends upon your own physiology , and we are all different. You should look at your blood level of 25hydroxyD3 , this is the measure of your vitamin D3 status, not the absolute number of I.U. that you are taking. Your liver converts the Vitamin D that you take into 25hydroxyD3, found in your bloodstream. So it depends upon how efficient your liver is in making the conversion, it depends on your body fat levels, because Vit D is stored in fat as well. IF it turns out that even high levels of supplementation will not raise your blood levels, due to lack of absorbtion in your gut, then alternative methods may be necessary. Sunlight is the original and best way to get your vitamin d level up. Only UVB light creates vitamin D in the skin. In the UK , it takes about 20 mins , for a white skin ,in direct sunshine , in the middle of the day , 10 am - 3 pm , to make vitamin D , but only in the summer months. In the months NOV to March , you cannot make any by sunshine. In april and october, it will only occur around solar noon , i.e when the sun is highest in the sky, at an elevation of 45 degrees or more. Never never ever burn your skin in the sunshine, that is a bad idea. If you stay out about 1/2 the time it takes to make your skin slightly red( by the following morning ) , then that is half the MED ( minimal erythemal dose) for you. Everyone has different skin , with different amount of pigmentation. If your skin is black, you may need about 3 to 5 times as much sun. That is why black or dark skinned people , in UK, generally have lower levels of vitamin D , and that is why diseases of insuffiency are more prevalent in that population. eg rickets. etc.
One thing to bear in mind, is that suscreen will absorb the UVB , before it can work on your skin , . For instance Factor 15 will absorb 97% of the UVB , so you won't be making any Vit D. So leave off the sunscreen for 20 mins , if you are out sunbathing. Sunscreen is one of the reasons that we in the UK are so low on Vitamin D.
For the winter months you should consider a sunbed , that produces as close to natural sunlight as possible.( includes UVB , and not excessive UVA ) Again never ever burn, just half the MED . Some sunbeds are UVA only , and are not good for vitamin D .
For information : In the USA, the Institute of Medcine, IOM has recently put out a report that up to 4000 IU per day is a safe level of supplementation for adults. Their recommendation for the entire population is an RDA of 600 IU. BUT that 4000 is safe.
Hope this helps.