2. Protein for healthy muscle mass

Older women tend to sit more, exercise less. That compounds a natural aging process called sarcopenia, which is the loss of muscle mass. By the time women near 80 years, they may have lost as much as half of their skeletal muscle mass. Eating enough protein reduces the impact of that muscle wasting.

"Healthy plant-based diets that don't include meat, a major source of protein, can still provide plenty of protein if you make savvy choices," says Ewoldt. He recommends choosing more soy, quinoa, eggs, dairy, nuts, seeds and beans.

Your protein needs depend on how much you weigh. For women over 50, experts recommend 1 to 1.5 grams of protein per kilogram of weight (1 kilogram = 2.2 pounds). If you weigh 140 pounds, for instance, you would need at least 63 grams of protein a day.