Skin cancer is the most commonly diagnosed cancer, with 5 million new cases each year.

Posted on 05/05/2016

The most common cause of skin cancer is the sun. So most people think they're helping when they slather on sunscreen. And people think that when it comes to the sun protection factor ("SPF") of sunscreens, "100" is better than "30"... and way better than "8."

But the opposite is true. The higher the number, the more risk you're taking with toxic chemicals.

Sunscreen is full of chemicals like nanoparticles, which several lab studies have shown to cause hemorrhaging and birth defects in fish and mice. And many sunscreens also contain oxybenzone, which causes cancer with light exposure (in other words, exactly when folks use sunscreens).

Too much sun exposure does increase the likelihood of getting certain skin cancers. It also wrinkles and discolors the skin, making us look older.

But remember... sun exposure is vital to good health. Vitamin D produced by the body from sunlight is critical in preventing diseases such as multiple sclerosis and depression.

That higher SPF is also a waste of money...

Sunscreens with SPF 8 block 87% of UVB rays (the ones that burn your skin). SPF 15 sunscreens filter out about 93%. SPF 30 blocks 97%. SPF 100 sunscreens block 99%.

So you are slathering on more toxic concentration for only marginally better protection if you use SPF 100 versus SPF 30.

And despite that high SPF, you're still not protected against UVA rays, which reach deeper levels of skin and increase your risk of developing certain types of skin cancer.

I prefer using SPF 8 when I can... It takes me about 20 minutes before I burn in strong sunlight, so with SPF 8, I get 160 minutes of protection. That's my burn rate (20 minutes) times the SPF (8).

If your burn rate is shorter... or if you plan to be outside longer... then go with a higher SPF. But try to keep it as low as possible. And unless you're planning a bad game of golf on the equator, I don't recommend ever using anything higher than SPF 30 (about 10 hours of protection at a 20-minute burn rate). You don't need that much goop.

You can also do a lot for your skin if you avoid sun exposure during the hours of 11 a.m. and 3 p.m., when the sun's rays are strongest.

But whatever you do, make sure that you do get outside this summer...

Getting enough sun is always on my annual list of top health tips. Sunlight is one of the best ways to fight depression and even cancer.

Taking a 30-minute walk provides your body with enough sunlight to generate the right levels of vitamin D. Do what I do and take a walk to get that sunlight on your skin. And remember that sunscreen can help protect you from intense sun damage, but avoid anything over SPF 30