The most common condiment is nuoc mam - fish sauce (made from salted and fermented anchovies), used in Vietnamese cooking much as Americans would use salt or Chinese would use soy sauce. Most also use MSG in their cooking.
Many Vietnamese lack calcium since sources such as milk, dairy products and soy products are not part of the diet. (Vietnamese of Chinese descent, however, may eat tofu and other soy products.) Further, many Vietnamese adults are lactose intolerant. Most Vietnamese children growing up in the U.S., however, drink milk.
Vietnamese in America may be susceptible to weight gain, high cholesterol and diabetes. Vietnamese desserts often include coconut milk and coconut oil - high in saturated fat. Vietnamese with diabetes may not realize that an excess of sweets can make their illness difficult to control. Vietnamese in the U.S. also tend to increase their meat consumption. Pork and chicken is cheaper here than in Vietnam. Many think of meat as more nutritious than other foods, and don't regard fish and vegetables as particularly nutritious. Further, if a Vietnamese patient already has diabetes, it may be difficult to change their diet, since rice - which converts to sugar and elevates blood sugar - is such a staple of the diet.
The Vietnamese diet can be high in sodium, with its reliance on fish sauce and MSG as common condiments, and low in fiber (with its lack of whole grains).