Is there more harm done cooking alkaline vegetables? If I gave you the short answer to that question then it would be a " no". Cooking your vegetables is purely dependent on the method you use.
Boiling is the worst way to cook your vegetables, because obviously key nutrients are extracted once over the 100 centigrade mark.
I steam my vegetables as opposed to boiling them and here are some of the reasons why this method of cooking is better.
Raw vegetables look quite vibrant but when steamed the hot water vapor seems to enhance the colour unlike boiling them. I promise you'll be attracted to broccoli once steamed.
More vitamin C
Vitamin C helps to combat free radicals which are free roaming molecules in the body that destroys cellular tissue and speeds up the aging process. Vitamin C is also required for healthy gums and strong teeth. Here's a fact... Boiling vegetables destroys 35% of the vitamin C content while steaming only gets rid of 15%. As you can see a big difference.
Eating raw is always going to provide the most nutrients but you can get plenty of other vitamin C from fruits if you're worried.
Chlorophyll does a similar job to that of haemoglobin. It helps to rebuild and replenish red blood cells and is important for eliminating carcinogens in the liver which is a harmful agent commonly found in cigarette smoke. Chlorophyll also helps to maintain all bodily detoxification systems by binding onto toxins like heavy metals. As you probably have guessed it, steaming retains more Chlorophyll then boiling.
Folic acid also known as vitamin B9 is important for avoiding anaemia and I have also heard is especially vital for pregnant women to take so that it prevents their child from being born with any adverse side effects. Many people lack their daily vitamins but you can get a good daily dose by either steaming some spinach, collard greens, mustard greens and many other dark leafy vegetables.
Most green vegetables have a certain degree of protein and helps stimulate testosterone production. Many bodybuilders know that they gain more mucle mass by steaming their aparaguses and broccoli so this should be enough information for you to want to steam your own vegetables.
Cooking your vegetables with a steamer is a lot faster and does not require any oils to roast your vegetables; therefore it can work out a lot cheaper too.
I have a multi-tiered steamer so that you can put the thicker vegetables at the bottom such as the carrots and cauliflower and green peas at the top where they require less steam.
In the winter season I would choose steaming vegetables over eating raw and vice versa in the summer. Dehydrators are also ideal for cooking vegetables raw by absorbing the water content inside and still keeping it warm.
The only downside to a dehydrator is that they are very demanding for kitchen space, which is why I would pick steaming overall, even if you lose a minimal amount of the nutrients.