As long as we’re on the subject, let me tackle a couple of other internet myths and misunderstandings about water.
Fact-checking the claim that having water with food is bad for digestion or absorption. Also: how much variety do you need in your fruits and vegetables to meet the requirement?
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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Hello and welcome to the Nutrition Diva podcast. I’m your host, Monica Reinagel, and today I have answers to two listener questions. Julie is wondering how drinking water with meals affects your ability to digest food and absorb nutrients. But first, Bob has a question about fruits and vegetables.
“I keep hearing that I should include fruits and vegetables in my daily diet. But how much variety do I need in order to meet the requirement? Can I just eat apples, bananas, broccoli, and corn, or do I need more variety?”
You’re right that eating plenty of produce is one of the cornerstones of a healthy diet. Fruits and vegetables provide similar types of nutrients. They are both good sources of fiber, antioxidants, and various phytonutrients (which simply means “plant-based nutrients”) that have been linked to a wide variety of health benefits. Of course, fruits tend to be higher in sugar than vegetables. Which makes them an easier sell, in some ways.
To the extent that people may struggle to incorporate fruit on a regular basis, it’s usually an issue of planning, logistics, habits, or access – and not that they don’t enjoy it. Personally, I like to use fruit to satisfy my sweet tooth in a healthier way.
I recommend aiming for five servings of vegetables and two to three servings of fruit each day. But if you wanted to skip the fruit and eat extra vegetables instead, I’d have absolutely no objection!
People who eat more vegetables end up eating less junk food, are more likely to maintain a healthy body weight, are less likely to have nutrient deficiencies, and, in general, are healthier and live longer.
But data show that getting a greater variety of produce also improves your overall nutrient intake and reduces your risk factors for several diseases—independent of the amount you are eating. Those of you who are familiar with my Nutrition GPA app will know that you earn points by eating 5 servings of vegetables over the course of the day. But you can also earn points simply by eating three different types of vegetables in a given day.
Every plant has a slightly different nutritional profile and provides unique phytonutrients. That doesn’t mean you have to eat them all! Plants from the same families tend to provide similar nutritional benefits. For example, cruciferous vegetables, which include things like broccoli, kale, cauliflower, cabbage, and Brussels sprouts, are rich in cancer-fighting compounds called glucosinolates.
Carrots, sweet potatoes, and winter squash are all good sources of carotenoids, which help protect your eyes and vision. Green beans, snow peas, and sugar snap peas are higher in protein than most veggies. Leafy greens are great sources of vitamin K and folate, which help keep your bones strong. And don’t forget about garlic, onions, and shallots—these members of the onion family contain anti-inflammatory flavonoids.
It’s a similar situation on the fruit side of the aisle: citrus fruit contain citrus bioflavonoids, berries and grapes are rich in anthocyanins, apples and pears are higher in fiber (especially if you eat the skins), bananas are famously rich in potassium, and so on.
So, even if you’re not quite getting five servings a day, you can do yourself a favor by playing the field a little. I’m not saying you have to have five different vegetables every day. But when you’re buying your veggies and fruit for the week, aim for an array of different colors and botanical families.
Julie recently emailed me with a question about drinking water during meals. She’d heard that it is bad for absorption. Other listeners have written with similar concerns about water diluting digestive juices and impairing digestion.
Let me put your mind at ease. Assuming you don’t have a digestive disorder, drinking water with your meals will not interfere with your ability to digest foods.
It is true that drinking a lot of water will dilute the stomach acid to some extent. However, the impact is mild—and transient, as the cells lining the stomach will secrete more hydrochloric acid if the pH of the stomach gets too high. After all, fruits and vegetables can be up to 96% water. If water impaired digestion, how would we ever digest them?
In fact, drinking water with meals helps your body process and break down food more effectively. And there are other advantages as well.
Your stomach is a little like a water balloon. When it’s empty, it’s relatively small and slack. When you fill it up, it stretches and gets tauter. And there are special nerve cells in the lining of your stomach called proprioceptors that detect this stretching and send a message to your brain that you’re full. Now, the only thing that these proprioceptors can sense is stretching. They can’t tell the difference between a pint of water and a pint of half and half. All they know is that something is filling your stomach.
If you’re watching your weight, you can use this to your advantage. People who drink a glass or two of water before they sit down to eat end up eating fewer calories, which can help with weight loss or maintenance. You can put the same strategy to work by choosing foods that have a higher water content (such as vegetables!) over those with less water.
As long as we’re on the subject, let me tackle a couple of other internet myths and misunderstandings about water. Here’s another listener email:
“I heard someone say that cold drinks will slow down the metabolism. So even if they are low in calories, they can slow weight loss. Is it true?”
This one is completely false (and not even logical). Drinking cold drinks actually helps you burn a few extra calories because your body has to spend energy to heat them up to body temperature.
But before you get too excited about ice water as a weight loss strategy, let’s do the math. Depending on how long it’s been since you were in high school, you might still have a dim memory of the definition of a calorie. A calorie is the amount of energy it takes to raise the temperature of 1 gram of water by 1 degree Celsius.
A 16-ounce glass of water is about 470 grams. The temperature of ice water is 0 degrees C, and body temperature is 37 degrees C. Thirty-seven times 470 equals 17,390 calories! Wow! That’s a whole lot more calories than you can burn in a half hour on the treadmill. But, there’s a small wrinkle.
When we talk about Calories in relation to food and nutrition, we’re really talking about kilocalories, or kcals. A stalk of celery, for example, actually contains 6,000 calories. To save the effort of writing all those zeros, we just say that a stalk of celery contains 6 kcals. In popular use, kcals are also referred to simply as Calories, but with a capital “c.”
So, drinking a glass of ice water burns just 17 kilocalories. To lose one pound, you’d have to drink 205 glasses of ice water. And even that isn’t quite accurate because we include the energy it takes to maintain your body temperature when we calculate how many calories you should be eating.
In terms of weight loss strategies, drinking cold water is really the long way around the block. Taking a brisk walk around that same block would be a lot more effective!
And finally, let me also debunk another rumor that occasionally makes the rounds: drinking ice water with meals will cause fats to congeal in your stomach and cause stomach or colon cancer. Once you drink it, ice water is fairly quickly brought up to body temperature.
Thanks to Bob and Julie for their questions today. If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com You can also leave me a message at 443-961-6206
And just a quick reminder that I’m hosting a 30-day nutrition challenge for my listeners (featuring the Nutrition GPA app I mentioned earlier). It starts on March 18th. If you’d like to join us, you can sign up at nutritionovereasy.com/upgrade