The following ten recommendations for a healthy diet were made by Nutrition Source of Harvard School of Public Health:
Choose good carbohydrates:
whole grains (the less processed the better), vegetables, fruits and beans. Avoid white bread, white rice, and the like as well as pastries, sugared sodas, and other highly processed food.
Pay attention to the protein package:
good choices include fish, poultry, nuts, and beans. Try to avoid red meat.
Choose foods containing healthy fats:
Plant oils, nuts, and fish are the best choices. Limit consumption of saturated fats, and avoid foods with trans fat.
Choose a fiber-filled diet:
Choose a fiber-filled diet which includes whole grains, vegetables, and fruits.
Eat more vegetables and fruits
Eat more vegetables and fruits—the more colorful and varied, the better.
Include adequate amounts of calcium in the diet:
however, milk is not the best or only source. Good sources of calcium are collards, bok choy, fortified soy milk, baked beans, and supplements containing calcium and vitamin D.
Prefer water over other beverages.
Avoid sugary drinks, and limit intake of juices and milk. Coffee, tea, artificially-sweetened drinks, 100-percent fruit juices, low-fat milk and alcohol can fit into a healthy diet but are best consumed in moderation. Sports drinks are recommended only for people who exercise more than an hour at a stretch to replace substances lost in sweat.
Limit salt intake.
Choose more fresh foods, instead of processed ones.
Drink alcohol in moderation.
Doing so has health benefits, but is not recommended for everyone.
Consider intake of daily multivitamin
Consider intake of daily multivitamin and extra vitamin D, as these have potential health benefits.
Other than nutrition, the guide recommends frequent physical exercise and maintaining a healthy body weight.
Others
The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do. Knowledge in this case is not, as of yet, power; would that it were so.
Marion Nestle expresses the mainstream view among scientists who study nutrition
The basic principles of good diets are so simple that I can summarize them in just ten words: eat less, move more, eat lots of fruits and vegetables. For additional clarification, a five-word modifier helps: go easy on junk foods. Follow these precepts and you will go a long way toward preventing the major diseases of our overfed society—coronary heart disease, certain cancers, diabetes, stroke, osteoporosis, and a host of others…. These precepts constitute the bottom line of what seem to be the far more complicated dietary recommendations of many health organizations and national and international governments—the forty-one “key recommendations” of the 2005 Dietary Guidelines, for example. … Although you may feel as though advice about nutrition is constantly changing, the basic ideas behind my four precepts have not changed in half a century. And they leave plenty of room for enjoying the pleasures of food.
Historically, a healthy diet was defined as a diet comprising more than 55% of carbohydrates, less than 30% of fat and about 15% of proteins.This view is currently shifting towards a more comprehensive framing of dietary needs as a global need of various nutrients.