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Raw or Cooked? How Best to Prep 11 Fruits and Vegetables

Fruits and vegetables contain a lot of nutrients and antioxidants like carotenoids, flavonoids, and polyphenols that can help prevent health issues like cancer and cardiovascular disease and can even help your mood. Antioxidants help your body counteract damage caused by toxic byproducts called free radicals. Eating more fruits and vegetables also increases your vitamin C, vitamin A, vitamin B6, thiamine, and niacin, minerals, and fiber.

But it can be tricky to know how you should store and prepare fresh foods to get the most nutrients.

Luckily, storing most fruits and vegetables generally does not lose antioxidants. In fact, antioxidant levels can even go up in the few days after you buy them. But when you start to see the fruit or vegetable spoil and turn brown, that usually means that they have started to lose their antioxidants. The main exceptions are broccoli, bananas, and apricots, which are more sensitive and start to lose their antioxidants in storage within days, so eat those sooner than later.

Here’s how you should prepare 11 fruits or vegetables in order to maximize antioxidants and nutrients.

1. Tomatoes. Cooked may be better than raw.

Storage tip: Even though this will make shelf life shorter, store tomatoes in room temperature since tomatoes can lose antioxidants (and flavor) when stored in cooler temperatures.
Cook your tomatoes to release higher levels of lycopene and overall antioxidants. You can cook them for up to 30 minutes at 190.4 degrees Fahrenheit (88 degrees Celsius). Lycopene is found in red fruits and vegetables like watermelon, red bell pepper, and papaya and has been linked to lower rates of cancer. Raw tomatoes have less overall antioxidants, but have more vitamin C.

2. Carrots. Raw or sous vide, steamed, boiled. Cooked can be better than raw.

Cook your carrots to get more beta-carotene, an antioxidant that gets converted in your body to vitamin A, which is good for your eyes and immune system.
Sous vide carrots for best results. Steaming or boiling carrots preserves more antioxidants than roasting, frying or microwaving. If you’re in Top Chef mode, try sous vide carrots — this method of sealing food in an airtight plastic bag and placing the bag into a water bath keeps even more antioxidants than steaming.

 3. Broccoli. Raw, steamed, or sous vide.

Storage tip: Keep broccoli wrapped in packaging in the refrigerator at 1 degree Celsius (or 33.8 degrees Fahrenheit). Unlike most vegetables, broccoli tends to lose antioxidants faster than other vegetables when stored without packaging, particularly when it starts to lose its color and turn yellow. Wrap the broccoli in microperforated or non-perforated packaging to keep antioxidants for longer.
If you eat raw broccoli, you’ll get higher levels of an enzyme called myrosinase, which creates compounds like sulforaphane, which blocks the growth of cancer cells and fight Helicobacter pylori, a bacteria responsible for stomach ulcers. Myrosinase is sensitive to heat and destroyed during cooking.

However, cooked broccoli and other cruciferous vegetables like cauliflower, have more indole, which is thought to be protective against cancer. Steamed broccoli has also better potential to reduce cholesterol than raw broccoli.

Sous vide or steamed broccoli to keep antioxidants. Steamed broccoli retains color and texture. Boiling broccoli for 9-15 minutes loses up to 60 percent of nutrients, which become leached into the water. Stir-frying loses the most vitamin C and nutrients.

4. Cauliflower. Raw, steamed, or sous vide.

Fresh raw cauliflower has 30 percent more protein and many different types of antioxidants such as quercetin. Raw cauliflower keeps the most antioxidants overall, but cooking cauliflower increases indole levels.

Don’t boil cauliflower in water because that loses the most antioxidants. Water-boiling and blanching causes the worst loss of minerals and antioxidant compounds in cauliflower because many of the nutrients get leached into the water. Steam or sous vide cauliflower to maintain nutrients.

5. Brussels sprouts, cabbage. Raw or steamed.

Brussels sprouts and cabbage are cruciferous vegetables rich in compounds protective against cancer. One study found that people who consumed about 300 grams or two-thirds pound of Brussels sprouts daily for a week had higher levels of a detox enzyme in the colon, which helps explain the link between eating cruciferous vegetables and lower risk of colorectal cancer.

Raw Brussels sprouts gives you the most folate and vitamin C. Like broccoli, steaming Brussels sprouts releases more indole than raw (but they admittedly taste best when roasted).

6. Kale. Raw or blanched.

Kale has beta-carotene, vitamin C, and polyphenols. Cooking kale significantly lowers vitamin C and overall antioxidants. Keep kale raw or, if you prefer cooked, blanch or steam kale to minimize antioxidant loss.

7. Eggplant. Grilled.

Grill eggplant to make it much richer in antioxidants compared to raw or boiled (and it tastes a lot better, too). Don’t forget to salt your eggplant slices before cooking to get rid of excess moisture and bitterness.

8. Red Peppers. Raw, stir-fried, or roasted.

Red peppers are a great source of vitamin C, carotenoids, polyphenols, and other phytochemicals. Raw red peppers provide more vitamin C because vitamin C breaks down with heat. But other antioxidants like carotenoids and ferulic acid go up when red peppers are cooked.

Stir-fry or roast red peppers. Do not boil red peppers — boiling red peppers loses the most nutrients and antioxidants. Stir-frying and roasting actually preserves red pepper antioxidants, more than steaming.

9. Garlic and onions. Raw or cooked.

Garlic and onions have been shown to help fight high blood pressure. Red onions have the highest amount of quercetin, a type of flavonoid family antioxidant thought to protect against certain forms of cancer, heart disease, and aging.

Garlic and onions are pretty hardy when cooked. You can blanch, fry, and even microwave them without changing their antioxidant levels by much, so use them however you like.

10. Artichokes. Steamed.

Cook your artichokes in order to boost their antioxidants. Steam artichokes to boost antioxidants levels by 15-fold and boil them to boost them by 8-fold. Microwaving them also increases an artichoke’s antioxidants. But don’t fry them — that gets rid of flavonoids, a type of antioxidant.

11. Blueberries. Raw or cooked.

Blueberries are one of the fruits with the highest levels of antioxidants, and you can eat them raw or cooked. One study found that some type of antioxidants levels went up with cooking blueberries, while others went down.

Some final tips on eating your fruits and vegetables:

  • Avoid deep frying. Bad news for vegetable tempura fans: Deep-frying vegetables creates free radicals from the hot oil. Not only are free radicals damaging for the body, but the vegetables lose much of their antioxidants in the process.
  • Fresh is generally better than frozen. Vegetables like spinach and cauliflower can lose B vitamins in the process of being frozen.
  • At the end of the day, prepare your fruits and vegetables so that you’ll be more likely to eat them. As long as you stay away from the deep fryer, fresh fruits and vegetables will generally give you a lot more nutrients and antioxidants than processed foods.
10/05/2015   By Marlynn Wei, MD, JD
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Eating Fried Potatoes Linked to Higher Risk of Death, Study Says

How your spuds are cooked is key to your health. People who eat fried potatoes two or more times a week double their risk of an early death compared to those who avoid them, a recent study published in the American Journal of Clinical Nutrition found.

Eating potatoes that have not been fried was not linked to a similar early mortality risk, the researchers noted.

“Fried potatoes consumption is increasing worldwide,” warned Dr. Nicola Veronese, lead author of the study and a scientist at the National Research Council in Padova, Italy.

In 2014, Americans consumed 112.1 pounds of potatoes per person, according to the National Potato Council. Of that total, 33.5 pounds were fresh potatoes, the remaining 78.5 pounds were processed. According to the US Department of Agriculture, the majority of processed potatoes North Americans eat are French fries.

Trans fats in fried potatoes

Veronese and his colleagues have been tracking 4,440 people aged 45 to 79 over a period of eight years to study osteoarthritis. This research team decided to momentarily set aside the main issue of osteoarthritis and look at participants’ consumption of potatoes.

Even though most of us may have assumed that fried potatoes could be unhealthy for us, there is “very limited” scientific data on this issue, Veronese explained in an email.

So the researchers divided study participants into subgroups based on how frequently they ate potatoes each week. Over the eight years, a total of 236 of the participants died. Analyzing the data for each group, Veronese and his team found that those who ate fried potatoes two to three times each week doubled their chance of dying early compared to those who ate no fried potatoes.

French fries, potato chips, hash browns – and any other preparation requiring a fryer – are all included under the umbrella of “fried potatoes,” Veronese explained.

Age or sex of participants did not influence the result, but the data showed men were more likely than women and younger participants were more likely than older participants to enjoy the fried food.

The study is observational, meaning the researchers simply tracked the behavior of a group of people and found an association between one behavior – eating fried potatoes – and another factor – early death. Because it is an observational study, Veronese and his co-authors note it cannot be said that eating fried potatoes directly causes an early mortality – it would require more research to draw such a firm conclusion.

“Even if it is an observational study, we believe that the cooking oil, rich in trans-fat, is an important factor in explaining mortality in those eating more potatoes,” said Veronese. Trans fat has been shown to raise the “bad,” or LDL, cholesterol in the blood, which can lead to cardiovascular disease.

 

Yet, he also added that “other important factors,” including obesity, a sedentary lifestyle and use of high quantities of salt might also play a role in the early death of those eating two or more portions of fried potatoes each week.

National Potato Council CEO John Keeling said the “study isn’t relevant to the general population” since the data was collected for an osteoarthritis study and includes only patients with arthritis. “Potatoes are inherently a very healthy vegetable,” said Keeling in an email. He said a medium-sized potato is 110 calories, has no fat, no sodium, no cholesterol, and provides nearly a third of the daily vitamin C requirement with more potassium than a banana.

“How the potato is prepared will impact the calorie, fat and sodium content,” said Keeling, however the basic nutrients remain “no matter how it is prepared.”

Based on the data in the study, Keeling said, “it is very much a stretch to brand fried potatoes, or any other form of potato, as unhealthy.”

Susanna Larsson, an associate professor at the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden, noted that the new study provides “no evidence” that potato consumption in and of itself may increase the risk of an early death. Larsson was not involved in the new study. Instead, it may be the “other factors” suggested by Veronese himself.

“Fried potato consumption may be an indicator of a less healthy (Western) dietary pattern which is associated with increased mortality,” said Larsson, who also conducted a study of potato consumption. Her study did not find an increased risk of cardiovascular disease linked to eating potatoes.

Understanding acrylamide

The potential danger when eating fried starchy foods, such as French fries, is acrylamide, said Stephanie Schiff, a registered dietitian at Northwell Health’s Huntington Hospital in Huntington, New York. Schiff was not involved in the study.

Acrylamide is “a chemical produced when starchy foods such as potatoes are fried, roasted or baked at a high temperature,” explained Schiff in an email. The browning process is actually a reaction that produces this chemical one shown to cause cancer in laboratory animals and considered toxic to humans, said Schiff. Acrylamide is also a potential cause of cancer, she said.

“You can reduce your intake of acrylamide by boiling or steaming starchy foods, rather than frying them,” said Schiff. “If you do fry foods, do it quickly.”

She also suggested you “go lighter” since “the darker the food, the more acrylamide it may contain.”

Finally, Schiff said that potatoes should not be stored in the refrigerator because this could lead to producing more acrylamide when the potatoes are later cooked.

“Increase your intake of fruits and vegetables for a healthier alternative,” said Schiff.

Veronese said he hopes his new study will suggest to everyone that consuming fried potatoes “could be an important risk factor for mortality. Thus, their consumption should be strongly limited.”

By Susan Scutti, CNN    Thu June 15, 2017
source: CNN


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The Healthiest Way to Cook Mushrooms Is Totally Surprising

Scientists have revealed the best way to cook mushrooms — and it’s not in a frying pan.
Mushrooms are healthy because of the significant amount of dietary fiber, protein, amino acids, vitamins (including B1, B2, B12, C, D and E) and trace minerals that they contain, as well as the fact that they’re low in fat and calories.

But, according to researchers from the Mushroom Technological Research Center of La Rioja in Spain, mushrooms’ composition, antioxidant capacity and nutritional content can be negatively affected by the cooking process.

For the study, which was published in the International Journal of Food Sciences, the team evaluated the influence of boiling, microwaving, grilling and frying white button, shiitake, oyster and king oyster mushrooms. After cooking the four types of mushrooms, which were chosen because they are the most widely consumed species of mushroom worldwide, the samples were freeze-dried and analyzed, with the results compared to raw versions.

The researchers concluded that the best way to cook mushrooms while still preserving their nutritional properties is to grill or microwave them, as the fried and boiled mushrooms showed significantly less antioxidant activity. The fried mushrooms in particular revealed a severe loss in protein and carbohydrate content, but an increase in fat.”Frying and boiling treatments produced more severe losses in proteins and antioxidants compounds, probably due to the leaching of soluble substances in the water or in the oil, which may significantly influence the nutritional value of the final product,” said Irene Roncero, one of the study’s authors, in a statement.

Kate Samuelson     May 22, 2017     TIME Health
 
source: time.com


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Still Cooking with Aluminum Foil? You’ll Want to Read This

Cooking and baking with aluminum foil is fast and convenient, and makes cleanup a cinch, but it’s not without health risks.

A lot has changed since aluminum arrived on the scene back in 1910, after the first aluminum foil rolling plant, Dr. Lauber, Neher & Cie, opened in Emmishofen, Switzerland. The first use of foil in the United States came about in 1913, when it was used to wrap Life Savers, candy bars, and gum. Eventually, aluminum foil made its way into American kitchens as a way to bake fish or roast vegetables on the barbecue, to line baking pans, and to trap steam when cooking.

And we’re using tons of it—so much that experts are getting concerned. Because according to research, some of the foil used in cooking, baking, and grilling leaches into your food, which can pose health problems over time.

According to the World Health Organization, human bodies are capable of properly releasing small amounts of aluminum efficiently, so it’s considered safe to ingest 40mg per kilogram of body weight of aluminum per day. Unfortunately, most people are ingesting far more than this.

Scientists have been looking at the potential threat that overexposure to aluminum may have on human health for years, and have found some disturbing results. For example, researchers have found high concentrations of aluminum in the brain tissue of patients with Alzheimer’s disease. Studies have also found that high aluminum intake may be linked to a reduction in the growth rate of human cells, and may be potentially harmful for patients with bone diseases or renal impairment.

A 2012 study published in the International Journal of Electrochemical Science investigated the amount of aluminum that leaches into food cooked with foil. The amount varied based on factors such as temperature and acidity (fish and tomatoes are highly acidic), but the findings showed conclusively that aluminum foil does leach into food cooked in foil. “Aluminum foil used in cooking provides an easy channel for the metal to enter the human body,” the study authors wrote. “The increase in cooking temperature causes more leaching. The leaching is also highly dependent on the pH value of the food solution, salt, and spices added to the food solutions.”

Ghada Bassioni, Associate Professor and Head of the Chemistry Division at Ain Shams University, conducted research with a group of colleagues that explored the use of aluminum for cooking and preparing food particularly at high temperatures. “The acidity of the food would enhance further leaching of aluminum into the meal,” she said, adding: “How aluminum will actually harm your body depends on many factors like your overall well-being and consequently how much your body can handle accumulation of it in relation to the allowable dosages set by the World Health Organization.”

So should you stop cooking with aluminum foil? It seems the general consensus is that we should, at the very least, cut way back.

For grilling veggies, you can get a stainless steel grilling basket, or even reusable skewers. Use a glass pan when roasting veggies in the oven; use a stainless steel cookie sheet under baking potatoes as opposed to aluminum foil to catch the mess; and even try replacing foil with banana leaves when wrapping foods for baking!

BY ALEXA ERICKSON
 
source: www.rd.com


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Microwaving food in plastic: Dangerous or not?

Let’s cover the original misinformation first: The earliest missives warned that microwaved plastic releases cancer-causing chemicals called dioxins into food. The problem with that warning is that plastics don’t contain dioxins. They are created when garbage, plastics, metals, wood, and other materials are burned. As long as you don’t burn your food in a microwave, you aren’t exposing yourself to dioxins.

Migrating chemicals

There’s no single substance called “plastic.” That term covers many materials made from an array of organic and inorganic compounds. Substances are often added to plastic to help shape or stabilize it. Two of these plasticizers are

  • bisphenol-A (BPA), added to make clear, hard plastic
  • phthalates, added to make plastic soft and flexible

BPA and phthalates are believed to be “endocrine disrupters.” These are substances that mimic human hormones, and not for the good.

When food is wrapped in plastic or placed in a plastic container and microwaved, BPA and phthalates may leak into the food. Any migration is likely to be greater with fatty foods such as meats and cheeses than with other foods.

The FDA long ago recognized the potential for small amounts of plasticizers to migrate into food. So it closely regulates plastic containers and materials that come into contact with food. The FDA requires manufacturers to test these containers using tests that meet FDA standards and specifications. It then reviews test data before approving a container for microwave use.

Some of these tests measure the migration of chemicals at temperatures that the container or wrap is likely to encounter during ordinary use. For microwave approval, the agency estimates the ratio of plastic surface area to food, how long the container is likely to be in the microwave, how often a person is likely to eat from the container, and how hot the food can be expected to get during microwaving. The scientists also measure the chemicals that leach into food and the extent to which they migrate in different kinds of foods. The maximum allowable amount is 100–1,000 times less per pound of body weight than the amount shown to harm laboratory animals over a lifetime of use. Only containers that pass this test can display a microwave-safe icon, the words “microwave safe,” or words to the effect that they’re approved for use in microwave ovens.

When Good Housekeeping microwaved food in 31 plastic containers, lids, and wraps, it found that almost none of the food contained plastic additives.

What about containers without a microwave-safe label? They aren’t necessarily unsafe; the FDA simply hasn’t determined whether it is or not.

man-microwave-dinner-into-mic

Is Styrofoam microwave safe?

Contrary to popular belief, some Styrofoam and other polystyrene containers can safely be used in the microwave. Just follow the same rule you follow for other plastic containers: Check the label.

The bottom line

Here are some things to keep in mind when using the microwave:

  • If you’re concerned about plastic wraps or containers in the microwave, transfer food to glass or ceramic containers labeled for use in microwave ovens.
  • Don’t let plastic wrap touch food during microwaving because it may melt. Wax paper, kitchen parchment paper, white paper towels, or a domed container that fits over a plate or bowl are better alternatives.
  • Most takeout containers, water bottles, and plastic tubs or jars made to hold margarine, yogurt, whipped topping, and foods such as cream cheese, mayonnaise, and mustard are not microwave-safe.
  • Microwavable takeout dinner trays are formulated for one-time use only and will say so on the package.
  • Old, scratched, or cracked containers, or those that have been microwaved many times, may leach out more plasticizers.
  • Don’t microwave plastic storage bags or plastic bags from the grocery store.
  • Before microwaving food, be sure to vent the container: leave the lid ajar, or lift the edge of the cover.

 Read more about the BPA controversy and get tips to decrease your exposure.

 Updated: October 27, 2015   Originally published: February 2006


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How to Cook Your Foods to Get the Most Nutrients Out of Them

By Franziska Spritzler / Authority Nutrition      February 17, 2016

Eating nutritious foods can improve your health and energy levels.

Surprisingly, the way you cook your food has a major effect on the amount of nutrients in it.

This article will explore how the different cooking methods affect the nutrient content of foods.

Nutrient Content is Often Altered During Cooking

Cooking food improves digestion and increases absorption of many nutrients.

For example, protein in cooked eggs is 180% more digestible than in raw eggs.

However, several key nutrients are reduced with some cooking methods.

Nutrients That May Decrease

The following nutrients are often reduced during cooking:

  • Water-soluble vitamins: vitamin C and the B vitamins — thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), folic acid (B7) and cobalamin (B8).
  • Fat-soluble vitamins: vitamins A, D, E and K.
  • Minerals: primarily potassium, magnesium, sodium and calcium

Bottom Line: Although cooking improves digestion and the absorption of many nutrients, the levels of some vitamins and minerals may decrease.

Boiling, Simmering and Poaching

Boiling, simmering and poaching are similar methods of water-based cooking.

These techniques differ by water temperature:

  • Poaching: less than 180°F/82°C.
  • Simmering: 185-200°F/85-93°C.
  • Boiling: 212°F/100°C.

Vegetables are generally a great source of vitamin C, but a large amount of it is lost when cooked in water.

In fact, boiling reduces vitamin C more than any other cooking method. Broccoli, spinach and lettuce may lose up to 50% or more of their vitamin C when boiled.

Because vitamin C is water-soluble and sensitive to heat, it can leach out of vegetables when they’re immersed in hot water.

B vitamins are similarly heat sensitive. Up to 60% of thiamin, niacin and other B vitamins may be lost when meat is simmered and its juices run off.

However, when the liquid containing these juices is consumed, 100% of the minerals and 70-90% of B vitamins are retained.

On the other hand, boiling fish was shown to preserve omega-3 fatty acid content significantly more than frying or microwaving.

Bottom Line: While water-based cooking methods cause the greatest losses of water-soluble vitamins, they have very little effect on omega-3 fats.

Grilling and Broiling

Grilling and broiling are similar methods of cooking with dry heat.

When grilling, the heat source comes from below, but when broiling, it comes from above.

Grilling is one of the most popular cooking methods because of the great flavor it gives food.

However, up to 40% of B vitamins and minerals may be lost during grilling or broiling when the nutrient-rich juice drips from the meat.

There are also concerns about polycyclic aromatic hydrocarbons (PAHs), which are potentially cancer-causing substances that form when meat is grilled and fat drips onto a hot surface.

Luckily, researchers have found that PAHs can be decreased by 41-89% if drippings are removed and smoke is minimized.

Bottom Line: Grilling and broiling provide great flavor but also reduce B vitamins. Grilling generates potentially cancer-causing substances.

Microwaving

Microwaving is an easy, convenient and safe method of cooking.

Short cooking times and reduced exposure to heat preserve the nutrients in microwaved food (9, 10).

Studies have found that microwaving is the best method for retaining the antioxidant activity in garlic and mushrooms.

About 20-30% of vitamin C in green vegetables is lost during microwaving, which is less than most cooking methods.

Bottom Line: Microwaving is a safe cooking method that preserves most nutrients due to short cooking times.

Roasting and Baking

Roasting and baking refer to cooking food in an oven with dry heat.

Although these terms are somewhat interchangeable, the term “roasting” is typically used for meat while “baking” is used for bread, muffins, cake and similar foods.

Most vitamin losses are minimal with this cooking method, including vitamin C.

However, due to long cooking times at high temperatures, B vitamins in roasted meat may decline by as much as 40%.

Bottom Line: Roasting or baking does not have a significant effect on most vitamins and minerals, with the exception of B vitamins.

stirfry

Sautéing and Stir-Frying

With sautéing and stir-frying, food is cooked in a saucepan over medium to high heat in a small amount of oil or butter.

These techniques are very similar, but with stir-frying the food is stirred often, the temperature is higher and the cooking time is shorter.

In general, this is a healthy way to prepare food.

Cooking for a short time without water prevents loss of B vitamins, and the addition of fat improves the absorption of plant compounds and antioxidants.

One study found that absorption of beta-carotene was 6.5 times greater in stir-friedcarrots than in raw.

In another study, blood lycopene levels increased 80% more when people consumedtomatoes sautéed in olive oil rather than without.

On the other hand, stir-frying has been shown to significantly reduce the amount of vitamin C in broccoli and red cabbage.

Bottom Line: Sautéing and stir-frying improve the absorption of fat-soluble vitamins and some plant compounds, but they decrease the amount of vitamin C in vegetables.

Frying

Frying involves cooking food in a large amount of fat, usually oil, at a high temperature. The food is often coated with batter or bread crumbs.

It’s a popular way of preparing food because the skin or coating maintains a seal, which ensures that the inside remains moist and cooks evenly.

The fat used for frying also makes the food taste very good.

However, not all foods are appropriate for frying.

Fatty fish are the best sources of omega-3 fatty acids, which have many health benefits. These fats are very delicate and prone to damage at high temperatures.

Frying tuna has been shown to degrade its omega-3 content by up to 70-85%, while baking caused only minimal losses.

In contrast, frying preserves vitamin C and B vitamins, and it may also increase the amount of fiber in potatoes by converting their starch into resistant starch.

When oil is heated to a high temperature for a long period of time, toxic substances called aldehydes are formed. Aldehydes have been linked to an increased risk of cancer and other diseases.

The type of oil, temperature and length of cooking time affect the amounts of aldehydes produced. Reheating oil also increases aldehyde formation.

If you’re going to fry food, don’t overcook it, and use one of the healthiest oils for frying.

Bottom Line: Frying makes food taste delicious, and it can provide some benefits when healthy oils are used. It’s best to avoid frying fatty fish and minimize frying time for other foods.

Steaming

Steaming is one of the best cooking methods for preserving nutrients, including water-soluble vitamins that are sensitive to heat and water.

Researchers have found that steaming broccoli,spinach and lettuce reduces their vitamin C content by only 9-15%.

The downside is that steamed vegetables may taste bland. However, this is easy to remedy by adding some seasoning and oil or butter after cooking.

Try this easy recipe for steamed broccoli with suggested additions to improve the flavor.

Bottom Line: Steaming is one of the best cooking methods for preserving nutrients, including water-soluble vitamins.

Tips to Maximize Nutrient Retention During Cooking

Here are 10 tips to reduce nutrient loss while cooking:

  1. Use as little water as possible for poaching or boiling.
  2. Consume the liquid left in the pan after cooking vegetables.
  3. Add back juices from meat that drip into the pan.
  4. Don’t peel vegetables until after cooking them. Better yet, don’t peel at all to maximize fiber and nutrient density.
  5. Cook vegetables in smaller amounts of water to reduce loss of vitamin C and B vitamins.
  6. Try to finish cooked vegetables within a day or two, as vitamin C content may continue to decline when the cooked food is exposed to air.
  7. Cut food after rather than before cooking, if possible. When food is cooked whole, less of it is exposed to heat and water.
  8. Cook vegetables for only a few minutes whenever possible.
  9. When cooking meat, poultry and fish, use the shortest cooking time needed for safe consumption.
  10. Don’t use baking soda when cooking vegetables. Although it helps maintain color, vitamin C will be lost in the alkaline environment produced by baking soda.

Bottom Line: There are many ways to preserve the nutrient content in foods without sacrificing taste or other qualities.

Take Home Message

It’s important to select the right cooking method to maximize the nutritional quality of your meal.

However, there is no perfect method of cooking that retains all nutrients.

In general, cooking for shorter periods at lower temperatures with minimal water will produce the best results.

Don’t let the nutrients in your food go down the drain.

Franziska Spritzler has a BSc in nutrition and dietetics. She is a Registered Dietitian and Certified Diabetes Educator with expertise in carbohydrate-restricted diets for diabetes and weight management.


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Do Vegetables Lose Their Nutritional Value When Heated?

Frying these foods will give you a major boost in important disease-fighting vitamins

While frying can reduce the nutritional value of most foods, there’s an exception to the rule:

It’s a group of foods that contain significant amounts of the organic pigments called carotenoids, which studies indicate can help reduce the risk of several chronic diseases in humans, like heart disease, eye disease, and certain cancers.

When you expose carotenoids to high temperatures, energy from the heat breaks them down. This makes it easier for the body to absorb into your bloodstream, where it goes to work against disease.

And if you fry those foods in oil, as opposed to steaming or baking them, you absorb even more because carotenoids are fat soluble.

Where to find carotenoids

Carotenoids are prevalent throughout nature, but the three that are most common in our foods are:

  • Pro-vitamin A carotenoids like alpha carotene and beta carotene, which gives carrots and sweet potatoes that iconic orange color and has been shown to reduce the risk of age-related macular degeneration — a leading cause of vision loss in people over 50.
  • Lycopene, which provides most red-hued fruits, like tomatoes, pink grapefruit, and red peppers, their color. About 80% of the lycopene we ingest comes from tomato-based products, and over the last decade, studies have found that the lycopene in tomatoes could be linked to a reduced rate of prostate, lung, and stomach cancers.
  • Lutein, which is found in dark leafy greens like kale and Brussels sprouts and has also been shown to reduce the risk of eye diseases, like age-related macular degeneration.

A major nutritional boost

So just how much more of these disease-fighting carotenoids do you get by pan frying them in oil (not to be mistaken for deep frying, which is an entirely different method of cooking)?

We asked Guy Crosby, who has spent 30 years in the commercial food industry business and is now the editor for America’s Test Kitchen and teaches a food science course at the Harvard School of Public Health. You can learn more about him on his site “The Cooking Science Guy.”

As Crosby explains:

“In the fresh tomato most of these [carotenoid] pigments are all tied up with proteins,” Crosby told Business Insider. “If you cook the tomato you break down the bonds between the proteins and the pigments — the lycopene — and you absorb about four times more lycopene into your blood from cooked tomatoes than from fresh tomatoes.”

But wait, there’s more: Carotenoids fall under a class of vitamins called fat soluble vitamins, as opposed to water soluble vitamins like Vitamin C and some types of Vitamin B. This means that carotenoids will dissolve in fats, for example the fat in frying oil, just like the Vitamin B-6 in broccoli dissolves in water when you boil it.

“Since lycopene is soluble in oil, if you cook your tomato in olive oil, you’ll absorb two times more again above and beyond from what you absorb from cooking tomatoes without the oil,” Crosby said.

Now, if you’re watching your waistline, it’s important to limit the amount of fat you ingest daily. And frying anything is certainly going to up the fat content.

However, you don’t need very much oil to get this boost in nutrition — about three to five grams of fat is enough, which is equivalent to one teaspoon of olive oil.

Serving Vegetables Makes You More Thoughtful, Less Boring

Fact or Fiction: Raw veggies are healthier than cooked ones
Do vegetables lose their nutritional value when heated?

By Sushma Subramanian  March 31, 2009

Cooking is crucial to our diets. It helps us digest food without expending huge amounts of energy. It softens food, such as cellulose fiber and raw meat, that our small teeth, weak jaws and digestive systems aren’t equipped to handle. And while we might hear from raw foodists that cooking kills vitamins and minerals in food (while also denaturing enzymes that aid digestion), it turns out raw vegetables are not always healthier.

A study published in The British Journal of Nutrition last year found that a group of 198 subjects who followed a strict raw food diet had normal levels of vitamin A and relatively high levels of beta-carotene (an antioxidant found in dark green and yellow fruits and vegetables), but low levels of the antioxidant lycopene.

Lycopene is a red pigment found predominantly in tomatoes and other rosy fruits such as watermelon, pink guava, red bell pepper and papaya. Several studies conducted in recent years (at Harvard Medical School, among others) have linked high intake of lycopene with a lower risk of cancer and heart attacks. Rui Hai Liu, an associate professor of food science at Cornell University who has researched lycopene, says that it may be an even more potent antioxidant than vitamin C.

One 2002 study he did (published in the Journal of Agriculture and Food Chemistry) found that cooking actually boosts the amount of lycopene in tomatoes. He tells ScientificAmerican.com that the level of one type of lycopene, cis-lycopene, in tomatoes rose 35 percent after he cooked them for 30 minutes at 190.4 degrees Fahrenheit (88 degrees Celsius). The reason, he says: the heat breaks down the plant’s thick cell walls and aids the body’s uptake of some nutrients that are bound to those cell walls.

Cooked carrots, spinach, mushrooms, asparagus, cabbage, peppers and many other vegetables also supply more antioxidants, such as carotenoids and ferulic acid, to the body than they do when raw, Liu says. At least, that is, if they’re boiled or steamed. A January 2008 report in the Journal of Agriculture and Food Chemistry said that boiling and steaming better preserves antioxidants, particularly carotenoids, in carrots, zucchini and broccoli, than frying, though boiling was deemed the best. The researchers studied the impact of the various cooking techniques on compounds such as carotenoids, ascorbic acid and polyphenols.

Deep fried foods are notorious sources of free radicals, caused by oil being continuously oxidized when it is heated at high temperatures. These radicals, which are highly reactive because they have at least one unpaired electron, can injure cells in the body. The antioxidants in the oil and the vegetables get used up during frying in stabilizing the cycle of oxidation.

Another study published in the Journal of Agricultural and Food Chemistry in 2002 showed that cooking carrots increases their level of beta-carotene. Beta-carotene belongs to a group of antioxidant substances called carotenoids, which give fruits and vegetables their red, yellow, and orange colorings. The body converts beta-carotene into vitamin A, which plays an important role in vision, reproduction, bone growth and regulating the immune system.

The downside of cooking veggies, Liu says: it can destroy the vitamin C in them. He found that vitamin C levels declined by 10 percent in tomatoes cooked for two minutes—and 29 percent in tomatoes that were cooked for half an hour at 190.4 degrees F (88 degrees C). The reason is that Vitamin C, which is highly unstable, is easily degraded through oxidation, exposure to heat (it can increase the rate at which vitamin C reacts with oxygen in the air) and through cooking in water (it dissolves in water).

Liu notes, however, that the trade-off may be worth it since vitamin C is prevalent in far more fruits and vegetables than is lycopene. Among them: broccoli, oranges, cauliflower, kale and carrots. Besides, cooked vegetables retain some of their vitamin C content.

That said, research shows that some veggies, including broccoli, are healthier raw rather than cooked. According to a study in the Journal of Agricultural and Food Chemistry in November 2007, heat damages the enzyme myrosinase, which breaks down glucosinates (compounds derived from glucose and an amino acid) in broccoli into a compound known as sulforaphane.

Research published in the journal Carcinogenesis in December 2008 found that sulforaphane might block the proliferation of and kill precancerous cells. A 2002 study in The Proceedings of the National Academy of Sciences also found that sulforaphane may help fight the bacterium Helicobacter pylori, which causes ulcers and increases a person’s risk of stomach cancer.

On the other hand, indole, an organic compound, is formed when certain plants, particularly cruciferous vegetables such as broccoli, cauliflower and cabbage, are cooked. According to research in The Journal of Nutrition in 2001, indole helps kill precancerous cells before they turn malignant. And while boiling carrots was found to increase carotenoid levels, another study found that it leads to a total loss of polyphenols, a group of chemicals found in raw carrots. Specific polyphenols have been shown to have antioxidant properties and to reduce the risk of cardiovascular disease and cancer, according to a 2005 report in The American Journal of Clinical Nutrition.

Comparing the healthfulness of raw and cooked food is complicated, and there are still many mysteries surrounding how the different molecules in plants interact with the human body. The bottom line, says Liu, is to eat your veggies and fruits no matter how they’re prepared.

“We cook them so they taste better,” Liu says. “If they taste better, we’re more likely to eat them.” And that’s the whole idea.

Jessica Orwig    Feb. 1, 2016