7. YOGURT
Why: Low- or no-fat plain yogurt is a terrific source of B vitamins, protein, calcium and --if it has active cultures--the healthy bacteria known as probiotics, which crowd out disease-causing germs.

How Much: Four or more cups a week, if this is your main dairy source.

How: Cut back on sugar and calories by choosing plain yogurt and adding fruit, especially berries, and some granola. Or be more inventive:

Mix a dash of vanilla and chopped mint into yogurt and dollop on fruit
Use yogurt instead of sour cream for dips, sauces and salad dressings
Top baked potatoes with yogurt and chives
Thicken sauces and make soups "creamy" with yogurt
The payback part? As one of the Harvard researchers would likely tell you, eating a diverse diet that is low in calories and high in nutrients can make your RealAge as much as 4 years younger.

7.酸奶

原因：低或者是无脂肪的纯酸奶是极好的维他命，蛋白质，和钙的来源并且如果有积极的文化——健康的细菌被认为是益生菌，它能排挤致病菌的侵入。

分量：一星期至少4杯，如果它的你的主要的乳制品来源

如何食用：减少糖和卡路里用纯酸奶和水果代替，特别是浆果类，和一些麦片。或者是更有创新的：

把香草和切碎的薄荷混合到酸奶和一块水果上，用酸奶代替酸腐的奶油用来调味酱和沙拉酱，表面涂酸奶和韭菜去烤土豆，勾芡酱汁和用酸奶做汤

回报的部分呢？作为哈佛大学的一位研究人员很可能会告诉你，一份不同的饮食——卡路里很低而营养很高，可以让你看上去比实际年龄年轻四岁。