The best nutrition advice sounds surprisingly simple—eat whole foods, preferably plants. But it gets tricky…once you consider that some whole foods are better than others when it comes to fighting major killers such as heart disease, cancer, diabetes and infections. For example, did you know that blueberries and blackberries far outperform other fruits as sources of antioxidants—substances that protect your cells from all sorts of damage?

Here’s the clincher: Before you assume that your diet is “good enough,” consider this—the number-one cause of death in the US is the Standard American Diet (SAD), according to research published in JAMA. For most leading causes of death, your genes account for only 10% to 20%. So getting your diet in optimal shape should be at the top of your priority list. Of course, fitting in all the nutrients backed by strong scientific evidence can be challenging. But it’s doable—if you build your diet around a few key foods. 

To keep it simple, nutrition expert Michael Greger, MD, FACLM, has spent more than a decade combing through the evidence to create his daily list of must-have foods… 

• Beans are a go-to source for healthy protein but also offer iron, zinc, fiber and potassium. What they do: Help lower cholesterol and high blood pressure and play a role in the prevention of colon cancer and stroke.

Which kinds to eat: Try a variety, including black beans, black-eyed peas, lentils, split peas and chickpeas. Canned beans are fine as long as you choose low-sodium varieties or simply rinse them well before using.

Daily dose: Three servings. A serving is one-quarter cup of hummus or bean dip or one-half cup of cooked beans. 

Note:I recommend legumes over meat because they are loaded with nutrients—and are naturally low in saturated fat and sodium and free of cholesterol.

• Berries are the fruits with extra bragging rights. What they do: Studies show that berries protect your brain, heart and liver, boost immunity and offer potential cancer protection.

Which kinds to eat: Blueberries and blackberries have the highest levels of antioxidants, as noted earlier, but others, including goji berries and cranberries, also pack nutritional punches. Helpful: Frozen berries retain most nutrients—if not more—than fresh.

Daily dose: One serving. That’s one-half cup of fresh or frozen berries. 

Other fruits shouldn’t scare you off because of their natural sugar. As long as you eat your fruit whole or blended, with its fiber intact, the sugar is not a health problem. What they do: Studies show that people who eats lots of whole fruits lower their risk for type 2 diabetes. 

Which kinds to eat: Everything from apples and watermelon to avocados.

Daily dose: Three servings. A serving is one medium-sized fruit or one cup of cut fruit.  

• Cruciferous vegetables are nutritional powerhouses that produce a chemical called sulforaphane, which is linked to a wide variety of health benefits. What they do: These vegetables may help fight cancer, boost liver function, manage type 2 diabetes and protect your brain and eyesight. 

Which kinds to eat: The category includes broccoli, kale, cabbage and cauliflower but also arugula, bok choy, collard greens and even horseradish. Important tip: Frozen versions will not produce sulforaphane—unless you sprinkle them with mustard powder,  which contains the necessary enzyme destroyed in the freezing process. 

Daily dose: One serving. That’s one-half cup of chopped vegetables, one-quarter cup of broccoli sprouts or one tablespoon of horseradish. 

• Greens. Dark green, leafy vegetables pack the most nutrition per calorie of any food. What they do: In research conducted at Harvard and published in JAMA and Annals of Internal Medicine, each additional daily serving of greens was linked to a 20% reduction in risk for heart attack and stroke. 

Which kinds to eat: The list includes many cruciferous vegetables, such as kale, collard greens and arugula, but also extends to other leafy greens such as spinach and mesclun salad mix. Helpful: If you find greens bitter, try mixing them with lightly sweetened dressings or fruits, such as fresh figs or grated apples. 

Daily dose: Two servings. A serving is one cup raw or one-half cup cooked. 

• Other vegetables should be included to get the “rainbow” effect of a bountiful veggie diet. What they do: People who eat a variety of vegetables (and fruits) show decreased signs of inflammation and lower rates of type 2 diabetes. 

Which kinds to eat: Get a colorful mix including artichokes, zucchini, asparagus, yams, beets and squash. Don’t forget onions, garlic and mushrooms (technically fungi). Plain white button mushrooms may offer the greatest health benefits.

Daily dose:Two servings. A serving is one cup raw or one-half cup cooked. Good rule of thumb: Fill half of every plate you eat with vegetables —ideally, including breakfast. 

• Flaxseeds are potent sources of lignans, plant estrogens that can dampen the sometimes harmful effects of the body’s own estrogens. What they do: Flaxseeds help fight breast cancer, high blood pressure and prostate enlargement.

What kinds to eat: Grind whole seeds or buy them pre-ground to help ensure that you’ll absorb the nutrients. The powder lasts about four months at room temperature and up to six months in the freezer. Sprinkle on oatmeal, salads, soups and other foods. 

Daily dose: One serving—one tablespoon ground. 

• Nuts and seeds are a perfect snack food. What they do: Nut eaters are less likely to die from cancer and heart and respiratory diseases, studies show. Nuts also can provide the fat that aids the absorption of plant nutrients. 

Which kinds to eat: Almonds, Brazil nuts, cashews, chia seeds, pistachios, pumpkin seeds and sunflower seeds are all good, but the evidence is strongest for walnuts, which are high in ­omega-3 fats and antioxidants. 

Daily dose: One serving. That’s one-quarter cup of nuts or seeds or two tablespoons of nut or seed butter.

• Herbs and spices add flavor, color and antioxidants. What they do: Herbs and spices help control blood pressure when they are used in place of salt. One standout, turmeric, contains a pigment, curcumin, which is particularly beneficial for brain health. Turmeric is linked to reduced inflammation and anticancer effects.  

Which kinds to eat: Grate fresh turmeric root to use in cooking or add a raw slice to a smoothie. Sprinkle turmeric powder onto sweet potatoes or roasted cauliflower. Use other spices, from basil to thyme, to flavor everything. Spices make a great substitute for salt.

Daily dose: One-quarter teaspoon of turmeric powder (or one-quarter inch raw), plus any other salt-free herbs and spices you like. 

• Whole grains including bread, rice, cereal and even pasta can be part of a healthy diet—as long as they come in whole-grain form. What they do: Reduce risks for heart disease, type 2 diabetes and stroke. 

Which kinds to eat: Branch out beyond wheat, oat and corn to quinoa, amaranth, millet, buckwheat and sorghum. Labels should list whole grains. The best products are high in fiber (at least 5 g per serving) and contain little or no added sugar. 

Daily dose: Three servings. A serving is one-half cup of hot cereal or pasta, one tortilla or slice of bread or three cups of popped popcorn.