What are the makings of a great salad? You need fresh greens, of course, and then a layer of colorful vegetables like tomatoes and carrots.
That's a good start. But to help the body absorb more of the nutrients packed into this medley, you may want to add something else: a cooked egg.
A small study published in May in the American Journal of Clinical Nutrition concludes that adding eggs to salads makes it easier to absorb the carotenoids in the raw vegetables. Carotenoids are the yellowish-red pigments that give carrots and tomatoes — and lots of other fruits and vegetables — their color. Two famous ones are beta carotene and lycopene. In addition to giving us those pretty colors, they're also beneficial phyonutrients that help fight inflammation.
For the study, the researchers gave 16 participants raw mixed-vegetable salad with no eggs, a salad with one and a half eggs and a salad with three eggs. They found that the absorption of carotenoids was 3.8-fold higher when the salad included three eggs compared to no eggs.
Now, we should point out that the study was funded by a grant from the American Egg Board's Egg Nutrition Center, which may raise eyebrows. But the scientists at Purdue University who carried out the study say they worked independently. And the findings hold up, since the scientific mechanism behind this phenomenon is well-documented in other studies.
It's the fat in the egg yolk that is responsible for upping the nutrient intake. And, as we've reported, oil-based salad dressing helps accomplish the same goal.
The dynamic duo of eggs and carrots (or any other vegetable or fruit high in carotenoids) got us wondering about other food power couples. Turns out, they're not so hard to find.
"The impact of consuming one food with another on the absorption of nutrients is well known in nutrition science," Wayne Campbell, professor of nutrition science at Purdue University and lead author of the egg and salad study, tells The Salt. "Sometimes the impact may be positive and at other times negative."
A classic example: After corn is soaked in lime and water, then ground up, all kinds of nutrients in the corn are released and made available for absorption — calcium, iron, niacin and minerals. This is why corn tortillas have been one of the bedrocks of Mesoamerican cuisine for millennia.
So what about some other foods that you might as well throw together if you've got them on hand?
Campbell tells us that eating something high in vitamin C, like a red pepper, helps convert the nonheme iron in plant foods and iron-fortified foods into a chemical form that promotes absorption. (The other form of iron is heme iron, which is only found in meat and seafood.) Sounds like a good excuse to go Tex-Mex and stir some peppers into your black beans.
And while we're on the subject of beans, why not eat your hummus with whole wheat bread? Oh, you already do? Good. Because it turns out that you get all the plant-based amino acids you need from the chickpeas and sesame seeds (in the tahini) in the hummus if you combine them with whole wheat bread. This combo is a vegetarian staple for a reason: It's a complete protein.
If you're reaching for the turmeric to add to a curry, make sure you throw some black pepper in there, too. Drew Ramsey, the Columbia University psychiatrist-turned-kale evangelist, tells us that this combination makes curcumin, the pigment in turmeric that has anti-inflammatory and anticancer properties, easier for the body to access. One study showed that the alkaloid in the pepper boosted the availability of curcumin in turmeric by 2,000 percent.
Wondering why we paired yogurt with sunglasses? If you really want to take advantage of all the calcium that's in your yogurt, you're going to need some vitamin D. Campbell says calcium absorption depends on having enough vitamin D in your gut.
Of course, not all pairings are beneficial. It turns out that phytates — a kind of acid — in things like tea and coffee may decrease the absorption of iron and zinc. So if you're having bacon with your morning coffee, you're not going to pick quite as many nutrients out of breakfast as you might otherwise.