Can you get vitamin E from lotion? Is rinsing quinoa really necessary? Are sprouts a good source of protein? What are the advantages of organic milk? Is this the healthiest way to cook broccoli?
If you are a long-time listener, you know that many of the topics I cover on the podcast are suggested by listeners. In fact, after 14 years of weekly episodes, I don't know what I would do without your questions and topic suggestions!
I've gotten a lot of great questions that don't require an entire episode to answer but that I'd love to respond to. Here are five of them. (In most cases, there are related episodes in the archives if you'd like to go deeper!)
Can you get Vitamin E through your skin?
Let's start with one that came in on the Nutrition Diva listener line (443-961-6206).
I have a question about topical vitamin E. I'm aware of that vitamin E supplements should be avoided with people who are taking blood thinners, but I was wondering if topical use would be an alternative way to help.
As I talked about in episode #293, vitamin E is one of the most common nutrient shortfalls. Although you don't need all that much (just 15 mg per day), nine out of ten Americans still fall short on vitamin E. And this listener is absolutely correct that people who are taking blood thinners (or who are preparing for surgery) are usually advised not to take vitamin E supplements. Vitamin E is a natural anti-coagulant and combining supplements with blood thinners can be too much of a good thing.
Vitamin E from foods is not a concern, however, and there are some advantages to getting vitamin E from foods rather than supplements. Most supplements only provide the alpha-tocopherol form of vitamin E, while foods provide a range of the different tocopherols and tocotrienols that make up the vitamin E family. Nuts, seeds, avocado, and whole grains are going to be your primary sources of natural vitamin E. (See this Vitamin E Cheat Sheet for details.)
But vitamin E is also a popular ingredient in skincare products, leading to this listener's question: Could you absorb vitamin E through your skin? And the answer is No.
As I explained in episode #465, while nutrients in topical formulas may have cosmetic effects on the surface of the skin, very little if any of those nutrients are penetrating beyond the skin’s surprisingly tough outer layers. That’s why we can slather our skin with mineral-based sunscreens all summer long without developing a zinc overload!
Does pre-chopping broccoli make it healthier?
Ross sent in a great question by email:
Does preparation and cooking method have a significant impact on the amount of sulforaphane in broccoli? And does this matter to our health?
Ross also helpfully linked to the online article he'd seen that prompted his question. (Note to other question-sender-inners: This is infinitely more helpful than telling me that you read something "somewhere" and asking me if it's true!)
The article Ross forwarded described a small study conducted by Chinese researchers to compare the amount of sulforaphane in broccoli cooked through a couple of different methods. Remember the broccoli sprout craze? That was about sulforaphane, a chemical in broccoli that has been found to have anti-cancer effects in test tube and animal studies.
The jury is still very much out on whether higher sulforaphane intake can reduce your risk of cancer beyond what simply eating more vegetables in general can do for you.
The amount of sulforaphane in broccoli is greatly reduced when you cook it. However, these Chinese researchers found that mincing the broccoli and then letting it sit for 90 minutes before stir-frying it results in a much higher sulforaphane content than other cooking methods.
Here's why: When you chew raw broccoli, you release an enzyme that converts glucosinolates in the vegetable to the magic sulforaphane compound. Chopping the broccoli also releases this enzyme and starts that conversion process. However, the enzyme is quickly destroyed by heat—at which point, conversion stops. As the researchers demonstrated, chopping it and letting it sit for 90 minutes maximizes sulforaphane production before the cooking process neutralizes the enzyme. And the finer you chop it, the better—at least from a sulforaphane perspective.
Personally, I can't see using pulverized broccoli in a stir-fry. But, extrapolating from this study, if you're making a pureed broccoli soup, you could chop up the broccoli and let it sit for an hour or two before adding it to your soup. And perhaps you'd get a bit more sulforaphane in the bargain. However, the impact of this on your overall health and disease risk is unclear.
This is a great example of the fact that sometimes something can be true without being terribly meaningful.
If you really want to double down on sulforaphane, including some raw broccoli florets in your salad or crudites platter is probably your best bet. But, in my opinion, the most nutritious way to prepare vegetables is the way you like them the best because those are the ones you'll eat.
Are sprouts a good source of protein?
Maddy left this question on the Nutrition Diva listener line:
I have heard a lot about the benefits of growing sprouts and how sprouts have all of the amino acids that you need in your diet. I was just wondering how good sprouts actually are for your diet. Do you recommend them?
Sprouted seeds (aka microgreens) can be a very nutritious option and they are fun to grow at home—especially in winter when your outdoor garden may be offline. Sprouted alfalfa, clover, radish, or broccoli seeds are great on salads or in place of lettuce on sandwiches or wraps. Like most greens, they in rich in vitamins C, A, and K and a host of other nutrients. And, as mentioned above, broccoli sprouts also contain potent cancer-fighting chemicals.
It's also true when seeds are sprouted, it increases their protein and essential amino content. However, they are still quite low in protein. A half-cup serving of alfalfa sprouts contains just half a gram of protein, for example. So, even if sprouts contain all the essential amino acids, they are not going to provide enough of them to meet your needs.
You can also sprout beans and other legumes; their heartier texture makes them good in soups, stir-fries, and omelets. Because these seeds are high in protein to start out with, the resulting sprouts will also be higher in protein, along with fiber, folic acid, and other B vitamins. A half-cup serving of sprouted kidney beans, for example, contains 4 grams of protein.
And finally, grains can be sprouted as well, which also increases their nutrient content somewhat and may make them more digestible. However, the nutritional differences between regular grains and sprouted grains aren't really big enough to have much of an impact on the overall nutritional quality of your diet. In other words, eat sprouted-grain products if you enjoy them (or the idea of them)—just don't eat more of them simply because they're sprouted. They are still considered grains, not vegetables.
Do you really need to rinse quinoa?
Here's a question from Brittany.
I recently found out about quinoa. Everything that I find online is saying that you have to wash it before you cook it. But on the NCBI website, there's a study that that says otherwise, so maybe you can give a little bit of a clarification.
Kudos to Brittany for looking to reputable sources to answer her nutrition questions! The National Center for Biotechnology Information (NCBI) is a branch of the National Institutes of Health.
As I talked about in Episode #393, the grain quinoa contains bitter compounds called saponins. (They get their name because they lather up in water, like soap suds.) Like many other phytocompounds, saponins are produced by plants as a method of natural pest control. The bitter taste makes the plant less palatable to birds, insects, and humans. But these chemicals often have health benefits. In fact, many of the phytocompounds thought to be beneficial to human health fall into this category of “natural pesticides.”
Although ingesting large amounts of saponins might cause some stomach irritation or other unpleasant effects, small amounts are generally harmless to humans. In fact, saponins are found in a variety of herbs, vegetables, and legumes.
Saponins are most concentrated in the leaves of the quinoa plant, which we don’t generally eat, as well as on the surface of the grains. You can remove the saponins by washing the grains before you cook them until they stop "sudsing." But a lot of brands are pre-washed to save you this step. And much of the quinoa for sale today has been bred to be lower in saponins to begin with because it gives the grain a sweeter, mellower taste and saves you the trouble of pre-washing it.
If you have a very sensitive stomach or other gut issues, you may want to give your quinoa a vigorous rinse before cooking it. Otherwise, check the package label. If it doesn't instruct you to rinse before cooking, you should be able to safely skip that step.
What's the advantage of buying organic milk?
And finally, this thoughtful question from Abigail (or, rather, Abigail's husband):
I was at the grocery store last week and organic milk cost the same as non-organic. So I got it, thinking, "We do consume a lot of milk. Maybe we should switch?" My husband asked me what is better about organic milk. I had no idea! Can you help me answer this?
I think most of us have the general idea that organic products are in some way superior to non-organic. But what exactly is the difference?
Organic products are not necessarily more nutritious than their conventional counterparts. Organic milk provides the same amount of protein and calcium as nonorganic milk. There are small differences in the fat content—not in the total amount, but in the types of fat. Organic milk is, on average, higher in omega-3 and other healthy fats. But because milk is not a big source of omega-3 to begin with, these small differences aren't going to have much impact on the overall nutritional quality of your diet.
Most of the difference between organic and conventional dairy has to do with how the cows are raised. Organic cows are given only organic feed and grazed only on pasture that is not treated with pesticides, for example. Routine use of antibiotics is also banned in organic dairy cows. Choosing organic dairy, therefore, is going to contribute to a reduction in agricultural use of pesticides and antibiotics on farms—which can definitely have some beneficial downstream effects.
But what about pesticides and antibiotic residues in the milk itself? Unfortunately, both conventional and organic milk contain residues from older pesticides that have since been banned but persist in the environment. There's not much we can do about that, given the nature of these "forever chemicals."
The most recent field tests conducted by the FDA found that residues from pesticides currently in use were detectable in less than 10% of the milk samples they tested, and none at levels thought to pose a risk. Similarly, all milk for sale in the US is tested for antibiotic residues. If antibiotics are detected above a very low threshold, the milk cannot be sold and must be dumped.
However, a recent analysis funded by the Organic Center found that none of the organic milk tested contained detectable residues of antibiotics or any pesticides currently in use. Choosing organic, therefore, can potentially reduce your exposure to these compounds from "very low" to "none at all."
The golden rule of toxicology, of course, is that the dose makes the poison. Something that is harmful at a certain level of exposure can be completely harmless at a lower level. And there's no data to show that drinking organic milk translates into lower health risks for milk drinkers. Nonetheless, I can understand the emotional appeal of reducing one's exposure to zero. And if the price of organic is the same as conventional, it would seem to be a no-brainer!
However, there are a few reasons why you might still decide to choose conventional. You might prioritize buying milk from a local dairy, for example, even if it is not an organic producer. A lot of the organic milk for sale these days is also ultra-pasteurized to extend the shelf-life. Although this doesn't affect the nutritional quality of the milk, a lot of people notice a difference in the taste. If the only conventionally-pasteurized option is non-organic, that might also tip the balance.
But, with a better understanding of what differentiates conventional from organic milk, you can make a more informed decision about what to buy (and why)!