Most canned and processed vegetables are much less nutritious than their raw counterparts. So is jarred spaghetti or canned tomato sauce good for you when compared to fresh? The answer may surprise you.
One of the most important antioxidants in tomatoes is lycopene, which has many suspected health benefits. There are studies and research which suggest it might be beneficial when it comes to asthma symptoms triggered by exercise (1), various eye disorders such as Age-Related Macular Degeneration (AMD) (2), cardiovascular benefits (heart disease, high blood pressure) (3), prostate inflammation (4), and anti-cancer properties (5). While all of these findings are preliminary and not conclusively proven, it's probably safe to assume that lycopene is good for us in at least some regard!
Unlike vitamin C and many other nutrients which are completely destroyed or diminished by heat, lycopene is one of the few which actually benefits from being heated. By doing so, the nutrient becomes more bioavailable to the human body for absorption (6). There have been a plethora of studies which have all validated this and for that reason, given that the results do not differ, it is universally considered as a fact. The only difference in studies is how much the absorption of tomato trans-lycopene increases after being exposed to heat. This makes tomato sauce jars and cans one of the very few foods which actually are more beneficial than eating the same vegetables fresh, at least when it comes to lycopene. It is true however that the amount of vitamin C in fresh will far outweigh any cooked tomato sauce, paste, or other processed products.
There is one aspect of canned tomato products which is extremely unhealthy and you need to be on the lookout for. It is the sodium content. This does not come naturally from the tomatoes, but rather it's salt added during the production process. The amount of sodium in spaghetti sauce can be absolutely staggering - 250 to 500 mg per serving is quite common, even for the organic jars and other brands which infer they are healthy.
In terms of the overall amount of antioxidants in tomato and spaghetti sauces, it is not very much judging by this ORAC value. Though an easy way to boost that is by adding fresh or dried spices such as basil, parsley, oregano, and marjoram which all score with very high ORAC values. The ORAC reflected above was taken before any spices or herbs have been incorporated into the sauce.
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010