Is a vegan diet the best defense against cancer and diseases like gout, diabetes?

Difficult to answer: A diet of caloric restriction and low in saturated fats would help in preventing some of the illnesses you mention. But a vegan can overeat, be obese, be a smoker, drink alcohol beyond moderation, not be physically active and be at risk for the diseases. Part of the etiology of the diseases in question is heredity, environmental factors and lack of exercise.

Not really: The long term effect of a low fat, vegan diet is malnutrition. Used for a short time (4-6 weeks) a low fat diet can be employed for weight loss. However, the long lerm effects of low fat diets are miserable. A low fat - high carb diet will lead to high Insulin levels, high triglcyerides, low hdl, metabolic syndrome and finally high blood pressure, diabetes and heart disease. www.edibolic.com.

Absolutely not: Vegans have the moral high ground, but despite all the claims by advocates, the really big prospective studies show no advantage or disadvantage for vegetarians / vegans in longevity or any of the common categories of disease. You'd do better to eat sensibly and keep up a fitness-focused lifestyle.