These days, being an adult is no longer an excuse not to eat your vegetables. And if you're a pill-popping health buff, you probably know that food is still the best source of vitamins. So which foods should you stock on? Here are the different essential vitamins and the foods that are the best sources for each:

The Antioxidants

There are certain oxygen molecules that, when used by the body, become highly unstable free radicals. These free radicals are the result of oxidation and can damage healthy cells. Free radicals can either be produced by the body or by pollutants like smog and cigarette smoke. To counter the effects of free radicals, antioxidants like Vitamins A, C, E, K and beta-carotene must be taken daily.

Some of the richest sources of antioxidants are listed below:

Vitamin A (or its precursor, beta-carotene) - carrots, pumpkins, green leafy vegetables (the darker the green color, the better) like romaine and lettuce. It's also found in sweet potatoes, apricots, broccoli, spinach, squashes, grapefruit and cantaloupes. When choosing foods rich with this vitamin, pick those with the most intense colors.

Vitamin C - also known as ascorbic acid, is found in many citrus fruits like lemons and oranges. It's also found in tomatoes, strawberries, sweet potatoes, turnip greens and again, in broccoli and cantaloupe.

Vitamin E - olives, asparagus, corn, wheat germ, nuts, green leafy vegetables and vegetable oils.

Vitamin K - cereals, spinach, soybeans, cauliflower and cabbage.

The B Vitamins

B1 - often found in fortified food like cereals, pasta and breads. Also sourced from whole grains, fish, lean meat, peas, soybeans, dairy products and some fruits and vegetables.

B2 or riboflavin - milk, meat, liver, dark green vegetables, mushrooms, cereals and whole grains.

B3 or niacin - lean meats, poultry, fish, liver, dairy products, legumes, nuts and eggs. Also found in enriched cereals and breads.

Folate - green leafy vegetables and folate-fortified foods.

B12 - meat, poultry, eggs, liver, kidneys, shellfish and dairy products.

Biotin and Pantothenic acid - fish, eggs, dairy products, lean beef, whole-grain cereals, broccoli and cabbages.

Combining foods

There are certain foods that contain more than one vitamin and you can benefit from them significantly. One orange, for example, contains Vitamin C and folate and extras such as calcium, potassium and some phytochemicals. Milk contains calcium, Vitamins A, B2, B12 and D. It also contains calcium.

There are also certain foods that can be fortified with vitamins to add to their health-enhancing properties. These days, you'll find vitamin-fortified breads, cereals, pasta and rice. The availability of vitamins in food makes it nearly impossible not to have a good source of nutrients in your diet. To ensure you get all the necessary vitamins you need, eat a variety of foods from different food groups.

Cooking vitamins

There are many ways to kill vitamins and one effective way is to cook them in a lot of water. Water-soluble vitamins are especially vulnerable to hot liquid which is why many nutritionists recommend using very little water when cooking vegetables. Steaming and stir-frying are cooking methods that are often used to save valuable nutrients and keep them in the food.

Another way of making sure no vitamins are lost is to use the liquid you cooked with and turn it into gravy, sauce or use it for soups. As for fat-soluble vitamins, cooking doesn't affect them as much.