Most health-conscious people have grown up with the idea that salt is only bad for those who are “salt-sensitive.” What is meant by this is that there is research that shows that the blood pressure in a certain minority of people will increase with salt.
However, what has emerged in the last ten years is a much more ugly picture of salt. Salt is not just a problem for the “sensitive” but for the population at large and, furthermore, it does not just elevate blood pressure but results in increased risk for a host of medical conditions.
NOTE: Read my link on How to Defeat Inflammation for more details
Consider what that all that extra salt in your diet, primarily from added salt and processed foods, will do to you according to the latest research:
1) Adiponectin. Many people have heard of the inflammatory markers TNF-alpha and C-Reactive protein. However, one lesser known inflammation-controlling protein is Adiponectin: the less you have, the higher your inflammation. Adiponectin can be whacked by being overweight and – you guessed it! – by salt intake.  Adiponectin levels likely play a role “in type 2 diabetes, obesity, atherosclerosis, non-alcoholic fatty liver disease (NAFLD) and an independent risk factor for metabolic syndrome”. 
Perhaps more scary is adiponectin’s correlation to stomach (gastric), prostate, and colon cancers as well as leukemia. In women, it has also been tied to endometrial and breast cancers 
What makes adiponectin so toxic and an apparent precursor to so many deadly conditions? The likely root cause is its role in increasing insulin resistance, a key factor in type II diabetes and Metabolic Syndrome.
2. Stomach, Colon, Testicular and Bladder Cancer. Higher salt intakes are now correlated with all four of these nasty cancers.  This likely also explains the previously mysterious link between GI cancers and processed meats, which are high in salt. 
4. Stroke and Cardiovascular Disease. A large, recent meta-analysis found that salt significantly increased the risk for both stroke and cardiovascular disease.  The authors pointed out that the risk was likely actually underestimated by the their study results as well.
1) Journal of Hypertension, Jun 2010, 28:36, “Salt Intake and Inflammation in Essential Hypertension: 1B.05”
3) European Journal of Cancer Prevention, Mar 2011, 20(2):132-139, “Salt, processed meat and the risk of cancer”
4) British Journal of Cancer, 2004, 90:128 134, “Salt and salted food intake and subsequent risk of gastric cancer among middle-aged Japanese men and women”
5) British Journal of Cancer, 2006, “Adiponectin and cancer: a systematic review”
6) BMJ, 2009; 339:b4567, “Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies”