Is vegetable juice just as good as whole vegetable?

At least 2 to 3 cups (16 to 24 ounces) of vegetables a day are recommended for most adults, depending on age, sex and level of physical activity. Any type of vegetable counts, including raw, cooked, fresh, frozen, canned and dried vegetables. One-hundred percent vegetable juice counts, too. You're right about the missing fiber, though. Vegetable juice has plenty of vitamins and minerals, but it's lower in fiber than is a serving of most whole vegetables. Without enough fiber in your diet, you may risk constipation, high cholesterol, high blood sugar and weight gain. Some types of vegetable juice are high in sodium, too.

Is it possible to take too much vitamin C?

Vitamin C (ascorbic acid) is a water-soluble vitamin that supports normal growth and development. Vitamin C also helps your body absorb iron. Because your body doesn't produce or store vitamin C, it's important to include vitamin C in your diet. For most people, a small glass of orange juice and a cup of strawberries, a medium orange, or a serving of broccoli provide enough vitamin C for the day. Any extra vitamin C will simply be flushed out of your body in your urine. Still, it's possible to have too much of a good thing. Although too much vitamin C from your diet is unlikely to harm you, megadoses of vitamin C supplements can cause nausea, diarrhea, kidney stones and inflammation of the stomach lining (gastritis). Rarely, too much vitamin C can cause faintness, dizziness and fatigue.

Are high-protein diets generally considered safe?

High-protein diets are generally well tolerated by healthy adults. But a dramatic increase in protein-rich foods may be dangerous for people with liver or kidney disease because they lack the ability to get rid of the waste products of protein metabolism.

Some protein is essential to human life. Protein is found in your bones, muscles, skin, organs, blood, hormones and enzymes. 

Your body can't store excess protein. During digestion and metabolism, protein is broken down into amino acids — the building blocks of protein. Your body uses these amino acids to make enzymes and other proteins. But any "extra" amino acids are stripped of nitrogen. The non-nitrogen parts of amino acids are used for energy or converted into fat, and the remaining nitrogen is eventually excreted by your kidneys and liver. These waste products have been shown to cause kidney injury, and in the presence of liver disease, excess nitrogen can cause further problems. High-protein diets may also increase the risk of kidney stones and osteoporosis. If you have kidney or liver disease or any chronic health condition, talk to your doctor before starting a new diet.