Superfoods are foods that stand out from the rest because of their unusually dense nutrient content. Superfoods generally have high amounts of antioxidants, vitamins, and minerals, for instance, and many also contain healthy fats, high-quality protein, and fiber.
What superfoods don't contain are added sugars, synthetic fats, and food additives, such as artificial colors and flavors.
Most any food that is heavily processed will not stand up to superfood criteria – but once you're eating primarily whole foods—foods that are as close to their natural state as possible—then basically everything you eat is a "superfood."
You need nutrients—all of them—and nutrients are found in abundance in fresh whole foods. That being said, certain superfoods can be combined with great synergy, which means that the whole is greater than the sum of its parts.
The following superfood combinations in particular, which were compiled by TIME,1 may be even healthier than eating the same foods on their own.
10 Best Superfood Combinations
1. Tomatoes + Olive Oil
Lycopene — a carotenoid antioxidant that gives fruits and vegetables like tomatoes and watermelon a pink or red color — is one of the key reasons why tomatoes are so good for you.
However, when you eat tomatoes with olive oil, the antioxidant activity of the lycopene is increased.2 Lycopene is a fat-soluble nutrient, which means eating it with some dietary fat is essential in order for it to be properly absorbed. But this doesn't explain the whole picture.
When researchers combined tomatoes with sunflower oil, the activity of lycopene did not increase, which suggests there's something especially beneficial about the olive oil.
If you're a fan of tomato sauce, you're in luck as well, as lycopene is one example of a nutrient that becomes more bioavailable when it's cooked. Research shows that cooking tomatoes (such as in tomato sauce or tomato paste) increases the lycopene content that can be absorbed by your body.
It also increases the total antioxidant activity. So one of the healthiest ways to consume tomatoes may be in an organic tomato sauce, drizzled with organic olive oil.
2. Wild-Caught Salmon + Collard Greens
Vitamin D helps your body to absorb calcium. In fact, if you have a vitamin D deficiency, it can cause a defect in putting calcium into the collagen matrix in your skeleton, leading to aches and pains.
In addition to being rich in vitamin K and phytonutrients that may help lower oxidative stress, fight inflammation, and prevent cancer, collard greens are rich in calcium. Wild-caught Alaskan salmon, meanwhile, contains some vitamin D, so consuming them together could theoretically be beneficial.
Wild-caught Alaskan salmon is high in healthy omega-3 fats and low in hazardous contaminants, and has about 988 IUs of vitamin D per 3.5-ounce serving.
It's important to note that farm-raised salmon does not have nearly this level of vitamin D, with only 245 IUs per 3.5-ounce serving.3
It is difficult, however, to get optimal levels of vitamin D from your diet alone, and a better solution is to get sensible exposure to the sun or a high-quality tanning bed.
This will ensure you have adequate vitamin D levels to absorb the dietary calcium you consume.
If you decide to take a vitamin D supplement, keep in mind that it will increase your body's need for vitamin K2. So when supplementing with oral vitamin D3, you need to make sure you're also increasing your K2 and magnesium intake.
The biological role of vitamin K2 is to help move calcium into the proper areas in your body, such as your bones and teeth. It also helps remove calcium from areas where it shouldn't be, such as in your arteries and soft tissues.
So vitamin K2 deficiency is actually what produces the symptoms of vitamin D toxicity, which includes inappropriate calcification that can lead to hardening of your arteries. If you want a natural dietary source of vitamin K2, fermented vegetables made with Kinetic Culture will produce high levels of K2.
3. Broccoli + Tomatoes
In addition to lycopene, tomatoes are an excellent source of lutein, zeaxanthin, and vitamin C (which is most concentrated in the jelly-like substance that surrounds the seeds), as well as vitamins A, E, and the B vitamins, potassium, manganese, and phosphorus.
Broccoli, meanwhile, is rich in vitamin K, vitamin C, folate, fiber and cancer-fighting compounds like sulforaphane. When rats were fed diets containing 10 percent broccoli, they had a 42 percent decrease in the growth of prostate cancer tumors.
When they were fed a diet containing 10 percent tomatoes, the growth rate dropped by 34 percent.
But when the rats were fed a diet with 10 percent broccoli and 10 percent tomatoes combined, the tumor weights decreased by 52 percent.4 So add some steamed broccoli to your tomato sauce or some raw broccoli and chopped tomatoes to your salad to boost their health potential.
4. Green Tea + Black Pepper
Black pepper contains a substance called piperine, which not only gives it its pungent flavor, but also blocks the formation of new fat cells.5 When combined with capsaicin and other substances, black pepper was also found to burn as many calories as taking a 20-minute walk.6
As an aside, black pepper also increases the bioavailability of just about all other foods -- herbs and other compounds included. Green tea, for instance, is recognized as an abundant source of epigallocatechin-3-gallate (EGCG), a catechin polyphenol shown to boost metabolism and protect against cancer.
Research shows that when EGCG is administered in combination with piperine, it increases the absorption of EGCG and helped it stay in the bloodstream longer. If the idea of sprinkling black pepper in your tea isn't appealing, TIME suggests:7
"Use the pair to soak meat or seafood. 'Brewed tea with garlic, ginger, and black pepper makes a perfect marinade,' [Cynthia] Sass [RD, MPH] says."
5. Turmeric + Black Pepper
Turmeric, the yellow-pigmented "curry spice" often used in Indian cuisine, contains curcumin, the polyphenol identified as its primary active component and which exhibits over 150 potentially therapeutic activities, which include antioxidant, anti-inflammatory, and anti-cancer properties.8
Black pepper or piperine is sometimes added to turmeric because it's believed to "heat up" the digestive system, which may help increase absorption. According to Melissa Rifkin, RD, a bariatric dietitian at Montefiore Medical Center in New York City, "If you pair the turmeric with the piperine, it improves the bioavailability of curcumin by 1000 times." 9