Optimal Nutrition

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Why do we need vitamin A?

Dear Reader,

Vitamin A is an essential, fat-soluble vitamin that has many diverse benefits for humans. Vitamin A promotes eyesight and helps us see in the dark; aids in the differentiation of cells of the skin (lining the outside of the body) and mucous membranes (linings inside of the body); helps the body fight off infection and sustain the immune system; and, supports growth and remodeling of bone. In addition, dietary vitamin A, in the form of beta carotene (an antioxidant), may help reduce your risk for certain cancers.

Adequate vitamin A intake is essential to human health. Vitamin A deficiency can lead to night blindness (inability to see in the dark or to recover sight quickly after being exposed to a flash of bright light in the dark) and xerophthalmia (progressive blindness that becomes irreversible if not treated in time with vitamin A).

Vitamin A deficiency can also reduce the health and integrity of skin and other epithelial tissues. The effect on skin can result in dry skin and hyperkeratosis (the development of clumps of skin around hair follicles). The effect on epithelial tissues can negatively affect the digestion and absorption of nutrients and cause infections of major systems and their organs (i.e., gastrointestinal, nervous/muscular, respiratory, and urogenital). In addition, bone growth can stop and normal bone remodeling can become impaired, resulting in anemia and weakened immunity.

The Recommended Dietary Allowance (RDA) for vitamin A is measured in retinol equivalents (RE), retinol being the active form of vitamin A. For adult men, the RDA is 900 micrograms of RE per day and for adult women it is 700 micrograms of RE per day.

Despite its benefits, too much Vitamin A can cause toxicity, the effects of which can vary depending on its source.  Excessive intake of vitamin A in dietary form is not harmful, but will cause one's skin to turn yellow in color. In contrast, large dose supplements (10 - 15 times the RDA) of vitamin A (as retinol) is harmful, and could result in the development of a fatty liver (hepatomegaly), dry skin, nausea, vomiting, fatigue, weakness, headaches, anorexia, and/or possibly increase the risk of birth defects among pregnant women. Symptoms depend upon whether or not vitamin A intake was taken over a long period of time (chronic) or a single excessive dose at one point in time (acute). In general, fat-soluble vitamins should not be consumed in excess of the recommendations because, unlike water-soluble vitamins in which the excess is excreted out of the body, an excess of fat-soluble vitamins will be stored and accumulated in the body.

It is highly recommended that vitamin A be consumed in the diet rather than from supplements. The richest sources of dietary vitamin A are liver, fish liver oils, milk, milk products, butter, and eggs. Liver is an especially rich source because vitamin A is primarily stored in the liver of animals and humans. Vitamin A is also found in a variety of dark green and deep orange fruits and vegetables, such as carrots, sweet potatoes, pumpkin, spinach, butternut squash, turnip greens, bok choy, mustard greens, and romaine lettuce. Beta carotene is the most active carotenoid (the red, orange, and yellow pigments) form of vitamin A. In addition, cooking (but not overcooking) increases the bioavailability of carotenoids in plant foods and absorption of dietary vitamin A is improved when consumed along with some fat in the same meal.

Hope this helps,

Alice

Recommended dietary allowances (RDAs) of nutrients?

Dear Reader,

RDAs (Recommended Dietary Allowances), prepared by the Food and Nutrition Board of the National Academy of Sciences, have been around for over 50 years, with periodic updates. The RDA is the average daily dietary intake level that would adequately meet the nutritional needs of nearly all (98 percent) healthy persons. RDAs include nutrients for which there is sufficient scientific evidence that they are required for good health. Their intention has always been to establish "standards to serve as a goal for good nutrition." RDAs provide the basis for evaluating the adequacy of diets of population groups. They are set at a level that includes a safety factor appropriate to each nutrient; so, this level actually exceeds the requirement for most individuals.

The Food and Nutrition Board has established Dietary Reference Intakes (DRIs). In addition to RDAs, DRIs include recommendations for food components for which RDAs cannot be established. Some of these include fat, carbohydrate, fiber, and plant estrogens, among others. DRIs also include maximum intake levels. Three dietary intake reference values for DRIs are:

  • Adequate Intake — the dietary intake level that would adequately sustain health when an RDA cannot be determined because of insufficient scientific evidence.
  • Estimated Average Requirement — the estimated dietary intake level that would maintain the health of half of a specified age and sex group.
  • Tolerable Upper Intake Level — the maximum level of daily nutrient intake that's apparently safe and unlikely to cause negative health effects in most healthy individuals.

DRIs and RDAs are not developed for specific individuals, but are for the making of policies for feeding programs, food labeling, and food fortification. The numbers signify levels of each compound that are appropriate for most healthy people in each category. To access information on RDAs and DRIs, check out the United States Department of Agriculture's (USDA) Food and Nutrition Information Center website.

Vitamin supplements may contain an amount equivalent to the RDA for DRI, but you'll probably not find a supplement with every imaginable nutrient, vitamin, and mineral. There are innumerable substances that keep us healthy, many of which cannot be packaged in a pill. In addition, many nutrients are difficult for the body to absorb when they come in pill form. Obtaining nutrients directly from a balanced diet of fruits, vegetables, whole grains, and lean proteins is still the recommended manner of giving your body all it needs to be healthy.

To assess whether your current diet is filled with nutrients, check out ChooseMyPlate.gov. You can also speak with your health care provider about whether you need a multivitamin or if the food you eat is sufficient. Students at Columbia can also make an appointment to speak with a registered dietician or a health care provider either through Medical Services (Morningside) or the Student Health Service (CUMC). Take care,

Alice

How can I eat well at college?

Dear Confused and College Bound,

You are not alone with your concerns. Going to college is a big step in a person's life involving major changes. You and those around you may be living on your own for the first time, making decisions on a buffet of issues, including what to eat.

Eating healthy at college is possible. Many college dining services are offering more healthy choices and are often quite receptive to students' concerns and dietary preferences. But, this is only part of the challenge. In an environment where time, friends, and finances may combine in new ways, having options available only solves some of the puzzle. It's important to experiment with what works best for you. For example, that traditional idea of three square meals a day has been updated with a more contemporary concept of eating five smaller meals spread throughout the day. Steer clear of diets or fads, especially those that drastically limit a particular nutrient. Remember, balance, moderation, and variety win out over trendy and extreme. For some practical tips, navigate through the many options on Choosemyplate.gov. Columbia students can also take advantage of the resources from the Get Balanced initiative. Plan ahead when possible so you don't have to rely on vending machines when you're hungry; think of ways to incorporate fruits, vegetables, and whole grains on a daily basis. Eating more of these will fill you up and possibly even enhance your already stellar brain power.

Making time for physical activity is important, too. Most college fitness centers have a variety of movement classes and options. When the weather is right, grab a friend and walk, run, bike, or blade outdoors. If you are Columbia affiliated, you can connect with the CU Move initiative.  CU Move encourages members of the Columbia community to engage in active lives that include regular physical activity. The program provides participants with motivation, incentives to be active throughout the year, and event calendars with access to plenty of free and low-cost physical activity options on campus and around NYC. 

Now, to address the second part of your question: an eating disorder, such as anorexia nervosa, is less about food, eating, and body weight. It has more to do with mental health, emotional, physical, socio-cultural, and family issues. If this is a particular concern of yours, you might want to take a look at Eating disorders vs. normal eating. Additionally, if you are a Columbia student, you can make an appointment with a health care provider or a registered dietitian to discuss your concerns by contacting Medical Services (Morningside) or the Student Health Service (CUMC).

Give yourself some time to adjust to a new environment and ask for help when you need it. Everything in moderation, even moderation. 

Enjoy your time at college,

Alice

Benefits of eating fiber

Dear Reader,

As they say, everything in moderation — including fiber! Eating enough fiber can have many health benefits, while too much may have consequences. By learning how much fiber you need, how much is in your food, and adjusting your diet accordingly, you’ll be able to strike a balance that’s ideal for your body (and your bowels). 

Fiber is basically composed of plant-based food matter (fruits, veggies, whole grains, and legumes) that can’t be broken down by your digestive system. Whole foods contain both soluble (dissolves in water) and insoluble (does not dissolve in water) fiber. Although the recommendations below don’t distinguish between these two types of fiber, they are different and have distinct functions — soluble fiber helps to reduce cholesterol and glucose levels, and insoluble fiber helps with constipation by increasing fecal bulk. 

Overall, fiber may lead to many health benefits, such as:

  • Keeping you regular. Fiber decreases the risk of constipation by bulking up and softening your stool.
  • Maintaining your bowel health. Fiber may prevent the development of diverticulitis and hemorrhoids. It has also been shown to reduce the symptoms of irritable bowel syndrome (IBS) in some cases.
  • Lowering cholesterol and blood glucose levels. By reducing bad (LDL) cholesterol and blood glucose levels, soluble fiber also leads to a decreased risk for cardiovascular disease, coronary heart disease, and type II diabetes.
  • Controlling your appetite/weight. Foods that contain fiber are typically low in fat, energy-dense, take more time to chew, keep you full for longer, and block some of the digestion of fats and proteins.
  • Preventing cancer. Fiber consumption may lower the risk for colorectal cancer, but the evidence is not yet conclusive.

Curious if you are getting enough fiber in your diet? You can use either the USDA Food List or WebMD’s Fiber-o-Meter to figure out the fiber content of the foods you eat and get suggestions for high-fiber foods. Making a habit out of reading the nutrition facts on food labels will also help. Generally, women need less fiber than men, and those aged 51 years or older need less than younger individuals. The following table can give you an idea of how much fiber you need on a daily basis:

 

Age 50 or younger

Age 51 or older

Men

38 grams

30 grams

Women

25 grams

21 grams

Source: Institute of Medicine

However, having too much fiber in one's diet can cause problems. When the intake of fiber is too high, it can replace other energy and nutrients that you need in your diet. Some insoluble fibers bind certain minerals, including calcium, magnesium, phosphorous, and iron. Too much fiber can also cause abdominal discomfort, gas, and diarrhea, and block the gastrointestinal (GI) tract if you add too much fiber too fast. For some, fiber supplements may potentially cause additional, more severe side effects such as allergic reactions and asthma, gastrointestinal distress, and drug and nutrient interactions. If you feel that you might benefit from taking fiber supplements, it's best to speak with a health care provider first to make sure it’s right for you.

So, before you load up on fiber, try adding it to your diet gradually, so that your GI tract has time to adapt. You'll also want to drink lots of fluids to keep the fiber soft. Choosing a variety of soluble and insoluble fiber-rich food sources, such as fruits, vegetables, whole grain breads and cereals, and legumes (beans and peas) will ensure that not only will you get a good mix of fiber, but beneficial nutrients, too. Remember that brown rice and 100 percent whole wheat bread have more fiber than white rice or white bread. Also, eating the skins of your fruits and vegetables whenever possible can also help increase fiber intake. If you're a Columbia student and need advice or more information about incorporating fiber-rich foods into a balanced diet, you can make an appointment with a health care provider or a registered dietitian by contacting Medical Services (Morningside) or the Student Health Service (CUMC).

Hope this was helpful!

Alice

To supplement or not to supplement my diet

Dear Supplementally Confused,

It may depend on the type of dietary supplement. Supplements range from daily multi-vitamins and minerals to anabolic steroids. Certain supplements are recommended for various conditions. For example, calcium supplements are often encouraged to help prevent osteoporosis, and iron is recommended for those who are anemic. Pregnant women's increased nutritional needs may require that they supplement with vitamins and minerals. The performance enhancing supplements that are so widely advertised today (i.e., creatine, chromium picolinate, protein shakes, amino acids) are not needed by the average person.

The best way to get all of the nutrients your body needs is to eat a healthy diet. To do this, you should eat a variety of foods, have a good balance within the food groups (read Food Guidelines — How much is a serving?  for details), eat enough calories (at least 1200), and make nutrient-dense choices, such as whole wheat bread and skim milk as opposed to white bread and whole milk.

Although vitamin and mineral supplements serve an important purpose for some people, you cannot depend on pills alone to provide your body with the nutrients it needs. Pills do not have phytochemicals, the non-nutrient compounds found in plant-derived foods that have biological activity in the body. Approximately 150 phytochemicals are found in foods along with the vitamins and minerals the body needs. Phytochemicals play a very important role in helping the body defend itself against cancer and cancer-causing agents, and probably many other things as well. An example of a known phytochemical is beta-carotene, a carotenoid. It is found in deeply pigmented fruits and vegetables, such as carrots, sweet potatoes, tomatoes, spinach, broccoli, cantaloupe, pumpkin, and apricots. Carotenoids act as antioxidants, reducing the risk of cancer. Read Antioxidants for more info.

So the best bet is to do what you were told as a child and, "eat your fruits and veggies!" Five servings a day is a great start. If you do supplement, be careful not to overdose. More of a "good" thing is not necessarily good for you. Besides being expensive, over-supplementing can be harmful to you. For more information, read What's the difference between vitamins and minerals? from the Go Ask Alice! Nutrition & Physical Activity archives.

Alice

One cannot live on water alone

Dear Reader,

How much did you bet? It's time for your co-worker to pay up!

The human body can survive a surprisingly long time on water alone, but it is nowhere near six months. When the body is deprived of new fuel (i.e., food), it breaks into its energy reserves to keep going. The body stores energy in the form of carbohydrates, fats, and proteins.

After one day without food, the body will have used up its carbohydrates, which are stored as glycogen in liver and muscle cells. After that, it's on to the fat reserves. Your average Joe/Jane, weight-wise, has enough fat reserves to live for four to six weeks without food. After that, the body begins to use its protein reserves (basically, the body itself). Body proteins are used up at a much faster rate than fat, and you could really only get another two to three weeks out of protein. At that point, however, you can't really call it living since so much irreparable damage has been done to the body, including the brain.

Bottom line: an average person could live for about eight weeks on water alone, give or take about a week for an over- or underweight person, respectively.

Alice

How to eat your veggies, even if you don't like them

Dear Reader,

Eating fruits and vegetables is an essential part of maintaining good health. In 2011, the USDA launched its most recent food guide called Choose My Plate. Most health professionals and health promotion organizations, including the USDA, recommend eating at least five servings of fruits and vegetables daily. Or, in the case of the Choose My Plate campaign, make half of your plate fruits and vegetables.

Since eating vegetables is not very appealing to you, let's start by discussing ways to incorporate some essential vitamins and minerals into your diet via fruit. Look to a wide variety of fruits to take in more vitamins, minerals, and phytochemicals, which are plant substances that may ward off heart disease and certain forms of cancer. For example, a fruit salad composed of oranges, assorted berries, grapes, kiwi, bananas, apples, and peaches with fresh lime juice squeezed over it can be enjoyed as a delicious part of any meal or on its own as a snack. A piece of fruit, such as an apple or a pear, is also an excellent dessert and can be paired with protein, such as nut butter or cheese, to make a well balanced snack.

Now let's move to the incorporation of vegetables in a positive way. Vegetables can taste bitter, particularly when eaten raw. A good place to begin may be experimenting with roasting a few different vegetables to see what you may like. Roasting vegetables brings out their sweetness via a process called caramelization, which reveals the sugars in vegetables, causing them to taste sweeter. This works particularly well with root vegetables, such as onions, potatoes, sweet potatoes, turnips, and carrots. To roast vegetables, simply cut them into one-inch squares, toss with olive oil, salt, and pepper, place on a baking sheet, and put in an oven at 450 degrees for 30 to 40 minutes, tossing and turning throughout cooking. You will know they are done when they are golden brown, slightly crispy on the outside, and soft on the inside. Broccoli and cauliflower are also delicious when roasted. Feel free to experiment by adding grated parmesan or other cheeses, herbs, and spices to the vegetables after roasting. You can also look to "sweeter" vegetables, such as corn, peas, tomatoes, and carrots and incorporate them into pasta or rice dishes or put them together to make a salad. The Get Balanced! nutrition initiative offers some recipes to get you started, such as the Cilantro Corn Tomato Salad.

It is also possible to disguise vegetables in your food, similar to the way some parents do when their children don't eat their veggies. This is typically done using vegetable purees, which can be made at home simply by microwaving a vegetable and then pureeing it, or can be found in the freezer section (most often found are pureed sweet potatoes or squash) or as jars of baby food in the children's section of your grocery store. Purees can be added to stew, soup, pasta sauce, baked goods, etc.; the options are endless. There are several good cookbooks available that offer recipes that incorporate vegetable purees. You can also sneak in an extra veggie by making fruit smoothies with spinach added in — all you'll taste is the fruit!

In addition to purees, you can also incorporate vegetables into other foods. Examples include:

  • Make omelets with tomatoes, peppers, and/or mushrooms — be sure to sauté the vegetables first before adding the eggs.
  • Add broccoli and/or olives to your pizza.
  • Add chopped spinach and/or grated carrots and onions to turkey burgers or meatloaf.
  • Mix chopped carrot and celery into tuna or chicken salad.
  • Choose soups rich in vegetables, such as Minestrone or Gumbo.
  • Add peas, carrots, and/or zucchini to rice pilaf.

It's difficult to "force" yourself into liking a specific food, especially if you are turned off by the taste. Luckily, you can choose from a variety of vegetable options and cooking methods. Keep an open mind (and mouth), and perhaps you will come to enjoy some of these foods!

For more tips about healthy eating, fruits, and vegetables, check out the Optimal Nutrition section of the Go Ask Alice! archive, learn more about the tools from Columbia's Get Balanced initiative, or visit Choosemyplate.gov.

Alice

Ginkgo — what d'ya thinko?

Dear What D'Ya Thinko About Ginkgo,

Gingko (Latin name, Ginkgo biloba) has been part of Chinese traditional medicine for thousands of years. It is extracted from the leaves of the hardy ginkgo biloba tree and is available in a variety of forms, including teas and tablets. Proponents of ginkgo believe that consuming the leaves increases cerebral blood flow and prevents the lumping of platelets in brain tissue. They also believe that ginkgo has other health benefits, such as slowing memory loss, improving cognitive ability, and curing conditions such as asthma, PMS, multiple sclerosis, and sexual dysfunction. For one herb, that's quite a resume!

While some claims on the Ginkgo plant may have some merit, not all are backed by research. Some studies have found that ginkgo biloba has positive effects on cognitive ability, though others have found that this may not be true. Ginkgo has been found to have possible antioxidant properties, which means that it may help the body fight free radicals. Free radicals in the brain attack healthy cells, stealing the cells' electrons. As an antioxidant, ingested ginkgo provides a target for these hungry cells, allowing them to steal ginkgo's electrons rather than from the healthy cells. Ginkgo has been found to be helpful in some patients with claudication (painful legs due to clogged arteries) and dementia. Despite these findings, more research is needed to establish ginkgo as the panacea that it's believed to be.

So, let's say you decide to ginkgo. You may be wondering about the recommended dose. For adults 18 and older, common dosage is typically around 80 to 240 mg, and may be taken two to three times a day (depending on the reason for use). It’s recommended that if you’re just starting to take ginkgo, it’s best to not take any more than 120 mg per day to avoid some gastrointestinal upset. Ginkgo might be safe for children, but it's probably a good idea not to give it to them unless it's under the strict supervision of a health care provider.

Ginkgo, though it is natural, may cause side effects, such as bleeding, headache, nausea, dizziness, diarrhea, and allergic reactions (some of which may be severe). Moreover, the U.S. Food and Drug Administration does not regulate ginkgo or other supplements. As such, it's recommended you ask your health care provider, if you are considering taking ginkgo, especially if you have a bleeding disorder or if you are taking any other medications/supplements. For more information about ginkgo, you may want to check out the section on supplements and ergonenic aids in the Go Ask Alice! Nutrition & Physical Activity archives.

Doing your homework on complementary and alternative medicine is a wise step to take — be proud of yourself for learning more info before you gink-go or gink-no.

Alice

A healthy model is a model of health

Dear N,

Rather than prescribing you a "model's diet," as there are probably as many of them as there are models (both healthy and unhealthy), a better suggestion would be to follow the guidelines for a model diet — that is, start by resisting the urge to compare yourself to other models. Focusing on what's healthy for you is the healthiest runway to strut on.

You have already taken a step in the right direction by taking good care of yourself and your health:

Exercising regularly is fantastic for health and wellness. For a well-rounded exercise plan, be sure to include both cardio and weight training workouts. Current recommendations for a healthy dose of exercise for adults include 2 hours and 30 minutes (150 minutes) of moderate-intensity aerobic activity (i.e., brisk walking) every week, plus muscle-strengthening activities on 2 or more days per week that work all major muscle groups (legs, hips, back, abdomen, chest,  shoulders, and arms).

Meeting with a nutritionist or dietician can help you figure out a specific eating plan tailored for your energy and nutritional needs. According to the USDA’s 2011 MyPlate Plan, a healthy diet for a typical woman aged 19-30 includes 6 ounces of grains (with 3 ounces coming from whole grains), 2.5 cups of vegetables, 2 cups of fruit, 3 cups of dairy products, 5 1/2 ounces of protein (lean meats and beans) and up to 6 teaspoons from the oil group. Recommendations for a typical man aged 19-30 includes 8 ounces of grains, with at least 4 ounces coming from whole grains, 3 cups of vegetables, 2 cups of fruit, 3 cups of dairy products, 6 1/2 ounces of protein (lean meats and beans) and up to 7 teaspoons of foods from the oil group. With a balanced diet, men and women can eat still eat sweets and treats in moderation and maintain a healthy diet.

Getting your beauty sleep is important — both on and off the runway! While six solid hours can be enough for some people, others, especially people in their late teens and early 20s, need as many as nine or ten to be completely rested and alert. For sleep tips, you can check out the A!Sleep Site.  

Only your dietician can tell you how often you should meet with her/him in a given period of time. In addition, you might also meet with a health care provider at your university's health service for a physical or check-ups to make sure that your body stays healthy while you continue with your eating, exercise, and would-be modeling plans. Columbia students can make an appointment to discuss their nutritional concerns online through Open Communicator, or by calling x4-2284.

Good luck with your modeling debut. Following the above tips can help you make a lasting impression along your path to becoming a model of good health!

Alice

Could drinking too much soda lead to osteoporosis or kidney failure?

Dear Curious,

You may want to screw the cap back on that cola! It appears that there is an association between soda consumption and osteoporosis, as well as an association between soda consumption and markers for kidney disease in women who have a low to normal Body Mass Index (BMI). As with most foods and drinks, moderation is key to good health. A little information can go a long way, so keep on reading to learn more about these links.

Studies have shown an association between regular intake of colas that contain phosphoric acid and negative effects on the bone. Researchers hypothesize that a high level of phosphoric acid may lead the body to tap the bones for calcium to neutralize acids. Alternatively, researchers believe that osteoporosis could be a result of diet displacement — that is, heavy soda drinkers may not be drinking enough milk or fortified juices that are good sources of vitamin D and calcium. Just to note, the link between soda and osteoporosis was previously thought to be due to the carbonation in the soda — research has shown this association to be false.

As for kidney function, studies have found that women with low to normal BMIs who drink more than two cans of soda daily have about double the risk of developing albuminuria (the presence of the protein albumin in the urine) relative to those who don't drink that much soda. Albuminuria is a marker for developing early kidney disease. Researchers believe that this effect is more pronounced in low to normal weight women, because obesity already damages the kidneys and the extra damage from soda is likely to be less observable. It is unknown why the same effect is not seen in men. Additionally, studies have shown mixed results on the relationship between soda consumption and the development and recurrence of kidney stones.

In any case, reducing soda consumption can't be a bad thing. Not only are you playing it safe with regards to osteoporosis and kidney function, you're also avoiding a lot of extra calories and damage to your teeth. For tips on cutting down, check out Getting off colas, sodas, pop, fiz...oh, whatever!. Now raise your glass to better health! 

Alice

May 18, 2012

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Hmm...interesting. I also heard that cow's milk contains some protein which prompts the bones in your body to release calcium. There's supposodly support for high cow milk consumption and...
Hmm...interesting. I also heard that cow's milk contains some protein which prompts the bones in your body to release calcium. There's supposodly support for high cow milk consumption and osteoporosis.
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