The next time you have a check-up, don’t be surprised if your doctor hands you a prescription to walk. Yes, this simple activity that you’ve been doing since you were about a year old is now being touted as “the closest thing we have to a wonder drug,” in the words of Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention.

Of course, you probably know that any physical activity, including walking, is a boon to your overall health. But walking in particular comes with a host of benefits. Here’s a list of five that may surprise you.

1. It counteracts the effects of weight-promoting genes. Harvard researchers looked at 32 obesity-promoting genes in over 12,000 people to determine how much these genes actually contribute to body weight. They then discovered that, among the study participants who walked briskly for about an hour a day, the effects of those genes were cut in half.

2. It helps tame a sweet tooth. A pair of studies from the University of Exeter found that a 15-minute walk can curb cravings for chocolate and even reduce the amount of chocolate you eat in stressful situations. And the latest research confirms that walking can reduce cravings and intake of a variety of sugary snacks.

3. It reduces the risk of developing breast cancer. Researchers already know that any kind of physical activity blunts the risk of breast cancer. But an American Cancer Society study that zeroed in on walking found that women who walked seven or more hours a week had a 14% lower risk of breast cancer than those who walked three hours or fewer per week. And walking provided this protection even for the women with breast cancer risk factors, such as being overweight or using supplemental hormones.

4. It eases joint pain. Several studies have found that walking reduces arthritis-related pain, and that walking five to six miles a week can even prevent arthritis from forming in the first place. Walking protects the joints — especially the knees and hips, which are most susceptible to osteoarthritis — by lubricating them and strengthening the muscles that support them.

5. It boosts immune function. Walking can help protect you during cold and flu season. A study of over 1,000 men and women found that those who walked at least 20 minutes a day, at least 5 days a week, had 43% fewer sick days than those who exercised once a week or less. And if they did get sick, it was for a shorter duration, and their symptoms were milder.

Mobility — the ability to move purposefully around your environment — is vitally important to health and well-being.

Nearly one-third to one-half of adults ages 65 and older experience impaired mobility. At first, it may not seem like a big deal — many people with impaired mobility learn to just move a little more slowly and a little more deliberately. Some people work around the problem by relying on a cane or walker.

That’s why it’s important to intervene to either prevent future mobility impairments or reduce existing ones.But taking impaired mobility “lying down” can cause your health to spiral downward. As you move less, pounds may start to creep on. You might withdraw from social relationships and activities that challenge you mentally. Exercise may become difficult, and lack of activity can worsen many health problems. This cycle of physical, emotional, and mental decline further restricts mobility.

For most people, the ability to rely on their own bodies, skills, and mental agility is a crucial part of living a satisfying life. Having full mobility helps you fully engage with the world and fosters a sense of self-sufficiency that can help you live independently well into your later years.

Medications make a difference — generally a positive one — in the lives of many people. Insulin keeps blood sugar under control, cholesterol-lowering drugs can reduce the chances of having a heart attack, and thyroid medication can restore a normal hormone level. These are but a few examples.

At the same time, all drugs carry side effects, and can interact with other medications. For many medications, one or more side effects affect balance. And that can increase your chances of taking a fall. How? According to the Centers for Disease Control and Prevention, common problems include vision changes, dizziness or lightheadedness, drowsiness, and impaired alertness or judgment. Some medications may damage the inner ear, spurring temporary or permanent balance disorders.

How do I know if this is a problem for me?

Some of the commonly prescribed medications that can affect balance include:

• antidepressants
• anti-anxiety drugs
• antihistamines prescribed to relieve allergy symptoms
• blood pressure and other heart medications
• pain relievers, both prescription and nonprescription
• sleep aids (over-the-counter and prescription forms)

Sometimes the problem isn’t a single drug but the combination of medications being taken together. Older adults are especially vulnerable, because drugs are absorbed and broken down differently as people age.

If you are concerned about how your medications may be affecting your balance, call you doctor and ask to review the drugs you’re taking, the dose, and when you take them. It is never a good idea to just stop taking a medication without consulting your health care provider first. Doing so can create even more health risks.

This quick and simple salad is a delicious solution to the age-old question, “What’s for dinner?” It’s filled with wholesome ingredients, protein and fiber to enhance your hard earned fitness results.

Servings: 6 
Here’s what you need:

For the Salad

• 2 cooked chicken breasts, chopped
• 1.2 cup cherry tomatoes, quartered
• 1 Tablespoon red onion, minced
• 1/2 cup cucumber, chopped
• 4 cups romaine lettuce, chopped
• 4 strips, cooked nitrate-free bacon, chopped
• 1 avocado, chopped

For the Dressing

• 1/8 cup olive oil
• 2 Tablespoons lemon juice
• 1 packet stevia
• 1 teaspoon crushed garlic
• 1 teaspoon Dijon mustard

Instructions

1. Combine all of the salad ingredients in a large salad bowl. Mix to combine.
2. Combine all of the dressing ingredients in a small bowl. Drizzle over the salad and serve.

Nutritional Analysis: One serving equals: 218 calories, 12g fat, 189mg sodium, 5g carbohydrate, 4g fiber, and 22g protein

Our bodies can obtain vitamin D from diet and make it from sun exposure. Even with these two routes for obtaining vitamin D, however, inadequate vitamin D is common, and deficiencies can be found on all continents, in all ethnic groups, and across all ages—a major concern, given the many ways that vitamin D helps protect our health. (1) There are a number of factors that increase the risk of having inadequate vitamin D, among them, lifestyle, sunscreen use, geographic location, skin tone, age, and body weight.

• Lifestyle: People who spend less time outdoors, or who cover up with clothing when they are outdoors, get less exposure to the sun, so they make less vitamin D. (1)
• Sunscreen Use: Correctly-applied sunscreen blocks the harmful ultraviolet B rays that cause skin cancer, but it also blocks most of the skin’s production of vitamin D. So people who use sunscreen daily are more likely to be low in vitamin D. (1) But don’t ditch the sunscreen: The American Academy of Dermatologists says that sunlight exposure to unprotected skin increases the risk of skin cancer, and that there’s no safe level of sunlight exposure that allows you to make vitamin D without increasing skin cancer risk. Their advice? Use sunscreen or other sun protection daily, skip the tanning booths, and get your vitamin D from diet or supplements. (2) Some Vitamin D experts take issue with the American Academy of Dermatologists’ hard line on sun exposure, and they recommend a more moderate option: Put sunscreen on your face, and allow your arms and legs to get a small amount of unprotected sun exposure—say, 15 minutes max—before applying sunscreen or covering up. It’s still a matter of scientific debate.
• Geographic Location and Season: In the summer, if you sat out in a bathing suit on a sunny afternoon for long enough to turn your skin slightly pink, you could make plenty of vitamin D. Yet during the late autumn and winter, people who live at higher latitudes produce little or no vitamin D from the sun, because the sun is at too low an angle in the sky. In the northern hemisphere, people who live in Boston (U.S.), Edmonton (Canada), and Bergen (Norway) can’t make enough vitamin D from the sun for 4, 5, and 6 months out of the year. (3) In the southern hemisphere, residents of Buenos Aires (Argentina) and Cape Town (South Africa) can make far less vitamin D from the sun during their winter months (June through August) than they can during their spring and summer. (3) The body stores vitamin D from summer sun exposure, but it must last for many months. By late winter, many people in these higher-latitude locales are deficient. (1)
• Skin Tone: People who have a darker skin tone have more melanin in their skin, and this pigment is a “natural sunscreen” that slows down skin production of vitamin D. (3)  This the main reason why African Americans are more likely to be low in vitamin D. (4)
• Age: The ability to make vitamin D in the skin drops as we age, and is one of the reasons why older individuals are more likely to have low vitamin D levels. (1)
• Body Weight: People with excess body fat have lower vitamin D levels, so those who are overweight or obese have a higher risk of having inadequate vitamin D.  (1, 5, 6)

The bottom line: Low vitamin D can be found in all ethnic and age groups, around the world, for a host of reasons. Even if you are taking a standard multiple vitamin, the amount of vitamin D in most vitamins (400 IU) is not enough to prevent low blood levels. If you suspect that you are at risk of vitamin D deficiency, you can ask your physician to order a blood test for vitamin D.

Vitamin D Deficiency: A Global Concern

If you live north of the line connecting San Francisco to Philadelphia and Athens to Beijing, odds are that you don’t get enough vitamin D. The same holds true if you don’t get outside for at least a 15-minute daily walk in the sun. African-Americans and others with dark skin, as well as older individuals, tend to have much lower levels of vitamin D, as do people who are overweight or obese.

Worldwide, an estimated 1 billion people have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups. (1-3)  Indeed, in industrialized countries, doctors are even seeing the resurgence of rickets, the bone-weakening disease that had been largely eradicated through vitamin D fortification. (4-6)

Why are these widespread vitamin D deficiencies of such great concern? Because research conducted over the past decade suggests that vitamin D plays a much broader disease-fighting role than once thought.

Being “D-ficient” may increase the risk of a host of chronic diseases, such as osteoporosis, heart disease, some cancers, and multiple sclerosis, as well as infectious diseases, such as tuberculosis and even the seasonal flu.

Currently, there’s scientific debate about how much vitamin D people need each day. The Institute of Medicine, in a long-awaited report released on November 30, 2010 recommends tripling the daily vitamin D intake for children and adults in the U.S. and Canada, to 600 IU per day. (7) The report also recognized the safety of vitamin D by increasing the upper limit from 2,000 to 4,000 IU per day, and acknowledged that even at 4,000 IU per day, there was no good evidence of harm. The new guidelines, however, are overly conservative about the recommended intake, and they do not give enough weight to some of the latest science on vitamin D and health. For bone health and chronic disease prevention, many people are likely to need more vitamin D than even these new government guidelines recommend.

Vitamin D Sources and Function

Vitamin D is both a nutrient we eat and a hormone our bodies make. Few foods are naturally rich in vitamin D, so the biggest dietary sources of vitamin D are fortified foods and vitamin supplements. Good sources include dairy products and breakfast cereals (both of which are fortified with vitamin D), and fatty fish such as salmon and tuna.

The body also manufactures vitamin D from cholesterol, through a process triggered by the action of sunlight on skin, hence its nickname, “the sunshine vitamin.”  Yet some people do not make enough vitamin D from the sun, among them, people who have a darker skin tone, who are overweight, who are older, and who cover up when they are in the sun. (1)

Correctly applied sunscreen reduces our ability to absorb vitamin D by more than 90 percent. (8) And not all sunlight is created equal: The sun’s ultraviolet B (UVB) rays—the so-called “tanning” rays, and the rays that trigger the skin to produce vitamin D—are stronger near the equator and weaker at higher latitudes. So in the fall and winter, people who live at higher latitudes (in the northern U.S. and Europe, for example) can’t make much if any vitamin D from the sun. (8)

Vitamin D helps ensure that the body absorbs and retains calcium and phosphorus, both critical for building bone. Laboratory studies show that vitamin D can reduce cancer cell growth and plays a critical role in controlling infections. Many of the body’s organs and tissues have receptors for vitamin D, and scientists are still teasing out its other possible functions.

New Vitamin D Research: Beyond Building Bones

Several promising areas of vitamin D research look far beyond vitamin D’s role in building bones. And, as you might expect, the news media release a flurry of reports every time another study links vitamin D to some new ailment. These reports can be confusing, however, because some studies are stronger than others, and any report needs to be interpreted in the light of all other evidence. More answers may come from randomized trials, such as the VITamin D and OmegA-3 TriaL (VITAL), which will enroll 20,000 healthy men and women to see if taking 2,000 IU of vitamin D or 1,000 mg of fish oil daily lowers the risk of cancer, heart disease, and stroke.

Here, we provide an overview of some of the more promising areas of vitamin D research, highlighting the complex role of vitamin D in disease prevention—and the many unanswered questions that remain.

Vitamin D and Bone and Muscle Strength

Several studies link low vitamin D levels with an increased risk of fractures in older adults, and they suggest that vitamin D supplementation may prevent such fractures—as long as it is taken in a high enough dose. (9-13)

A summary of the evidence comes from a combined analysis of 12 fracture prevention trials that included more than 40,000 elderly people, most of them women. Researchers found that high intakes of vitamin D supplements—of about 800 IU per day—reduced hip and non-spine fractures by 20 percent, while lower intakes (400 IU or less) failed to offer any fracture prevention benefit. (13)

Vitamin D may also help increase muscle strength, which in turn helps to prevent falls, a common problem that leads to substantial disability and death in older people. (14-16)  Once again, vitamin D dose matters: A combined analysis of multiple studies found that taking 700 to 1,000 IU of vitamin D per day lowered the risk of falls by 19 percent, but taking 200 to 600 IU per day did not offer any such protection. (17)

A recent vitamin D trial drew headlines for its unexpected finding that a very high dose of vitamin D increased fracture and fall risk in older women. (18) The trial’s vitamin D dose—500,000 IU taken in a once-a-year pill—was much higher than previously tested in an annual regimen. After up to 5 years of treatment, women in the vitamin D group had a 15 percent higher fall risk and a 26 percent higher fracture risk than women who received the placebo.

It’s possible that giving the vitamin D in one large dose, rather than in several doses spread throughout the year, led to the increased risk. (18) The study authors note that only one other study—also a high-dose, once-a-year regimen—found vitamin D to increase fracture risk; no other studies have found vitamin D to increase the risk of falls. Furthermore, there’s strong evidence that more moderate doses of vitamin D taken daily or weekly protect against fractures and falls—and are safe.

So what is the significance of this study for people who want to take vitamin D supplements? A reasonable conclusion would be to continue taking moderate doses of vitamin D regularly, since these have a strong safety record, but to avoid extremely high single doses. This recent finding does present a challenge to scientists who will work to understand why the extreme single dose appears to have adverse effects.

Vitamin D and Heart Disease

The heart is basically a large muscle, and like skeletal muscle, it has receptors for vitamin D. (19) So perhaps it’s no surprise that studies are finding vitamin D deficiency may be linked to heart disease. The Health Professional Follow-Up Study checked the vitamin D blood levels in nearly 50,000 men who were healthy, and then followed them for 10 years. (20) They found that men who were deficient in vitamin D were twice as likely to have a heart attack as men who had adequate levels of vitamin D. Other studies have found that low vitamin D levels were associated with higher risk of heart failure, sudden cardiac death, stroke, overall cardiovascular disease, and cardiovascular death. (21-24) How exactly might vitamin D help prevent heart disease? There’s evidence that vitamin D plays a role in controlling blood pressure and preventing artery damage, and this may explain these findings. (25) Still, more research is needed before we can be confident of these benefits.

Vitamin D and Cancer

Nearly 30 years ago, researchers noticed an intriguing relationship between colon cancer deaths and geographic location: People who lived at higher latitudes, such as in the northern U.S., had higher rates of death from colon cancer than people who live closer to the equator. (26) Many scientific hypotheses about vitamin D and disease stem from studies that have compared solar radiation and disease rates in different countries. These can be a good starting point for other research but don’t provide the most definitive information. The sun’s UVB rays are weaker at higher latitudes, and in turn, people’s vitamin D levels in these high latitude locales tend to be lower. This led to the hypothesis that low vitamin D levels might somehow increase colon cancer risk. (2)

Since then, dozens of studies suggest an association between low vitamin D levels and increased risks of colon and other cancers. (1,27)  The evidence is strongest for colorectal cancer, with most (but not all) observational studies finding that the lower the vitamin D levels, the higher the risk of these diseases. (28-38) Vitamin D levels may also predict cancer survival, but evidence for this is still limited. (27) Yet finding such associations does not necessarily mean that taking vitamin D supplements will lower cancer risk.

The VITAL trial will look specifically at whether vitamin D supplements lower cancer risk. It will be years, though, before it releases any results. It could also fail to detect a real benefit of vitamin D, for several reasons: If people in the placebo group decide on their own to take vitamin D supplements, that could minimize any differences between the placebo group and the supplement group; the study may not follow participants for a long enough time to show a cancer prevention benefit; or study participants may be starting supplements too late in life to lower their cancer risk. In the meantime, based on the evidence to date, 16 scientists have circulated a “call for action” on vitamin D and cancer prevention: (27) Given the high rates of vitamin D deficiency in North America, the strong evidence for reduction of osteoporosis and fractures, the potential cancer-fighting benefits of vitamin D, and the low risk of vitamin D supplementation, they recommend widespread vitamin D supplementation of 2000 IU per day. (27)

Vitamin D and Immune Function

Vitamin D’s role in regulating the immune system has led scientists to explore two parallel research paths: Does vitamin D deficiency contribute to the development of multiple sclerosis, type 1 diabetes, and other so-called “autoimmune” diseases, where the body’s immune system attacks its own organs and tissues? And could vitamin D supplements help boost our body’s defenses to fight infectious disease, such as tuberculosis and seasonal flu? This is a hot research area and more findings will be emerging.

Vitamin D and Multiple Sclerosis: Multiple sclerosis (MS) rates are much higher far north (or far south) of the equator than in sunnier climes, and researchers suspect that chronic vitamin D deficiencies may be one reason why. One prospective study to look at this question found that among white men and women, those with the highest vitamin D blood levels had a 62 percent lower risk of developing MS than those with the lowest vitamin D levels. (39) The study didn’t find this effect among black men and women, most likely because there were fewer black study participants and most of them had low vitamin D levels, making it harder to find any link between vitamin D and MS if one exists.

Vitamin D and Type 1 Diabetes: Type 1 diabetes is another disease that varies with geography—a child in Finland is about 400 times more likely to develop it than a child in Venezuela. (40) Evidence that vitamin D may play a role in preventing type 1 diabetes comes from a 30-year study that followed more than 10,000 Finnish children from birth: Children who regularly received vitamin D supplements during infancy had a nearly 90 percent lower risk of developing type 1 diabetes than those who did not receive supplements. (41)  Other European case-control studies, when analyzed together, also suggest that vitamin D may help protect against type 1 diabetes. (42) No randomized controlled trials have tested this notion, and it is not clear that they would be possible to conduct.

Vitamin D, the Flu, and the Common Cold: The flu virus wreaks the most havoc in the winter, abating in the summer months. This seasonality led a British doctor to hypothesize that a sunlight-related “seasonal stimulus” triggered influenza outbreaks. (43) More than 20 years after this initial hypothesis, several scientists published a paper suggesting that vitamin D may be the seasonal stimulus. (44) Among the evidence they cite:

• Vitamin D levels are lowest in the winter months. (44) 
• The active form of vitamin D tempers the damaging inflammatory response of some white blood cells, while it also boosts immune cells’ production of microbe-fighting proteins. (44) 
• Children who have vitamin D-deficiency rickets are more likely to get respiratory infections, while children exposed to sunlight seem to have fewer respiratory infections. (44) 
• Adults who have low vitamin D levels are more likely to report having had a recent cough, cold, or upper respiratory tract infection. (45)

A recent randomized controlled trial in Japanese school children tested whether taking daily vitamin D supplements would prevent seasonal flu. (46) The trial followed nearly 340 children for four months during the height of the winter flu season. Half of the study participants received pills that contained 1,200 IU of vitamin D; the other half received placebo pills. Researchers found that type A influenza rates in the vitamin D group were about 40 percent lower than in the placebo group; there was no significant difference in type B influenza rates. This was a small but promising study, and more research is needed before we can definitively say that vitamin D protects against the flu. But don’t skip your flu shot, even if vitamin D has some benefit.

Vitamin D and Tuberculosis: Before the advent of antibiotics, sunlight and sun lamps were part of the standard treatment for tuberculosis (TB). (47) More recent research suggests that the “sunshine vitamin” may be linked to TB risk. Several case-control studies, when analyzed together, suggest that people diagnosed with tuberculosis have lower vitamin D levels than healthy people of similar age and other characteristics. (48)   Such studies do not follow individuals over time, so they cannot tell us whether vitamin D deficiency led to the increased TB risk or whether taking vitamin D supplements would prevent TB. There are also genetic differences in the receptor that binds vitamin D, and these differences may influence TB risk. (49) Again, more research is needed. (49)

Vitamin D and Risk of Premature Death

A promising report in the Archives of Internal Medicine suggests that taking vitamin D supplements may even reduce overall mortality rates: A combined analysis of multiple studies found that taking modest levels of vitamin D supplements was associated with a statistically significant 7 percent reduction in mortality from any cause. (50) The analysis looked at the findings from 18 randomized controlled trials that enrolled a total of nearly 60,000 study participants; most of the study participants took between 400 and 800 IU of vitamin D per day for an average of five years. Keep in mind that this analysis has several limitations, chief among them the fact that the studies it included were not designed to explore mortality in general, or explore specific causes of death. More research is needed before any broad claims can be made about vitamin D and mortality. (51)

Remember when a total cholesterol reading of under 200 was the standard for judging cardiovascular health? Today, of course, we know that it's the components of cholesterol (LDL, HDL, the size of those cholesterol particles, and triglycerides) that are much more predictive of heart health. Well, our understanding of total weight and its effects upon your heart has evolved in similar fashion. It's not your total weight but the characteristics of that weight—how much is fat and where it's deposited—that matter most.

Surprised? Thank the scientists at the Mayo Clinic, who are behind this recent discovery. After comparing various health markers with the weights and body mass index numbers of thousands of adults, they found that more than half of those with normal weights and BMIs actually had "high body-fat percentages as well as heart and metabolic disturbances." In other words, they had the same risks of coronary disease, diabetes, and other chronic illness as people who weighed much more.

This research, and its sobering implications for millions of Americans, led to the establishment of a new condition called normal weight obesity (NWO). This is more than just the latest fat phobia. It's worth paying attention to because the accumulation of fat in the body, especially in the belly and around internal organs, causes low-level inflammation that gradually damages tissue and blood vessels. (Think of it as metabolic rust.) So even though your weight or BMI may be within acceptable limits for your height and age, don't be lulled into a false sense of security. Do your own analysis, starting with these steps:

1. Stop being preoccupied with pounds. As with total cholesterol, total weight is just one general assessment of your health. Yes, people who are trying to lose weight are more likely to succeed if they weigh themselves often. But seeing numbers that are within a healthy BMI range may actually disguise your heart disease risk. Keep them in perspective.

2. Measure your body fat. For a quick estimate of this key factor, wrap a cloth measuring tape around your naked waist just above your belly button. If your weight is fairly normal but the number you see above your navel is 35 inches or more (40+ inches for men), you may have NWO. For a more exact reading, ask your doctor (or health club) to measure your body fat. This can be done using a variety of noninvasive methods. If it's higher than 30 percent (20 percent for men), you likely have NWO.

3. Get a blood test. Ask your doctor to order a thorough blood analysis at your next physical. Warning signs of NWO include low HDL (total cholesterol and LDL may be normal), along with elevated triglycerides, blood sugar, and blood pressure.

4. Target belly fat. If you're diagnosed with NWO, take aim at visceral fat. Despite how entrenched it may seem, you can lose it. The keys are: Avoid the white stuff (white bread, rice, pasta, and other refined carbohydrates). Add monounsaturated fats, which target belly fat, to your diet. And do interval exercises to burn more fat and strength-training to build lean body mass.

5. Keep tracking fat. Just as you hop on the scale to keep tabs on your weight, do the same with your body fat. Have it measured periodically at your doctor's office or health club. Or just observe the notches where your belt buckles.

Conversely, if you're considered overweight by current standards, there may be some good news here. If your body-fat percentage is lower than 30 percent (20 percent for men) and your blood chemistry is normal, then you are among the "fat and fit." (Many athletes are in this category.) Continue to eat smart and exercise, but accept your body for what it is and know you're not unhealthy because of it. Feeling fat and feeling healthy are no longer mutually exclusive.

More Heart-Healthy Advice

Staying hydrated is one simple way to keep blood pressure in the safe zone.

Resting heart rate. The average heart rate for a person at rest is 60 - 80 beats per minute. It is usually lower for people who are physically fit, and often rises as you get older. You can determine your resting heart rate by counting how many times your heart beats in one minute. The best time to do this is in the morning after a good night's sleep before you get out of bed. Maximum heart rate. To determine your own maximum heart rate per minute subtract your age from 220. For example, if you are 45, you would calculate your maximum heart rate as follows: 220 - 45 = 175. Target heart rate. Your target rate is 50 - 75% of your maximum heart rate. You should measure your pulse off and on while you exercise to make sure you stay within this range. After about 6 months of regular exercise, you may be able to increase your target heart rate to 85% (but only if you can comfortably do so). Certain heart medications may lower your maximum and target heart rates. Always check with your doctor before starting an exercise program. Note: Swimmers should use a heart rate target of 75% of the maximum and then subtract 12 beats per minute. The reason for this is that swimming will not raise the heart rate quite as much as other sports because of the so-called "diving reflex," which causes the heart to slow down automatically when the body is immersed in water. VO2 Max. Serious exercisers may use a VO2 max calculation, which measures the amount of oxygen consumed during intensive, all-out exercise. The most accurate testing method uses computers, but anyone can estimate V02 without instrumentation (with an accuracy of about 95%): After running at top pace for 15 minutes, round off the distance run to the nearest 25 meters. Divide that number by 15. Subtract 133. Multiply the total by 0.172, and then add 33.3. Olympic and professional athletes train for VO2 max levels above 80. A VO2 max equaling between 50 and 80 is considered an excellent score for overall fitness. For the average person exercising for fitness and health, this value is not necessary. To determine your maximum heart rate, subtract your age from 220. This number represents how many times your heart should beat per minute at its maximum rate. Multiply that number by 0.6 and 0.85 to determine the range of heart rate to strive for. Healthy people can build up gradually to sustain this heart rate for 30 to 45 minutes at least 3 times a week to build aerobic fitness. The health benefits of exercise depend more on regular activity than on pace, intensity, and heart rate.

What is dehydration? Dehydration is the excessive loss of water from the body, as from illness or fluid deprivation. Any person who exercises on a regular basis is susceptible to the effects of even mild fluid loss. The value of the body's most important nutrient, water, cannot be underestimated. Exercise produces body heat, and too much body heat reduces exercise capacity. As the core body temperature rises, blood flow to the skin increases, and the body attempts to cool itself by sweating. During intense exercise, the body temperature rises as high as 39 degrees Celsius (105 degrees Fahrenheit) and the muscle temperature can rise as high as 40 degrees Celsius (108 degrees Fahrenheit). These temperatures make exercise difficult because the body and muscles are competing for blood. As the body temperature rises, oxygen becomes more of a commodity due to increased circulatory demands. Oxygen is needed to help with the cooling process, and reduces the amount of oxygen available for vital organs, which can lead to severe health risks as well as a drop in athletic performance. When you start exercising, as much as two percent of the body water is lost. Although this amount is considered a "normal" range for humans, it is certainly not an optimum level for athletic performance. Below is a table that summarizes the effects of minimal fluid loss during exercise.
		PHYSICAL SYMPTOMS AND EFFECTS OF DEHYDRATION
Body Water Lost Symptoms     1 % Few symptoms or signs of any thirst present; however, there is a marked reduction in VO2 max. 2% Beginning to feel thirsty; loss of endurance capacity and appetite. 3% Dry mouth; performance impaired. 4% Increased effort for exercise, impatience, apathy, vague discomfort, loss of appetite. 5% Difficulty concentrating, increased pulse and breathing, slowing of pace. 6-7% Further impairment of temperature regulation, higher pulse and breathing, flushed skin, sleepiness, tingling, stumbling, headache. 8-9% Dizziness, labored breathing, mental confusion, further weakness. 10% Muscle spasms, loss of balance, swelling of tongue. 11% Heat Exhaustion, delirium, stroke, difficulty swallowing; death can occur. Dehydration can cause any or all of the following: • Increased heart rate (beats per minute) • Increased lactate acid in muscles (increased blood acidity) • Increased body temperature • Decreased strength • Any of the following medical conditions: heat cramping, heat exhaustion & heat stroke The best way to avoid fluid loss is often the simplest: drink plenty of fluids. Water is sufficient to replenish the fluids that are lost during exercise. However, water cannot replace the minerals that are lost during exercise-induced sweating. Sweating releases potassium, sodium and calcium, which are vital for survival. These minerals, also known as electrolytes, are not found in water. It is therefore advisable to consume a supplement, which contains these added minerals, before any strenuous exercise. One such supplement that contains these electrolytes is a “sports drink.” Although these sports drinks can contain a combination of vitamins and minerals, they also contain simple and complex carbohydrates, predominantly simple sugars, which provide the athlete with an added amount of glucose. This glucose, which is converted by the body into fuel, can later be used to power working muscles. The carbohydrates that are found in sports drinks are designed, when used as directed, to help in performance, but do not play a direct role in hydration. The added nutrients, potassium, sodium, and calcium, along with the water content of the sports drink, are the determining factors in hydration. Exercise scientists, along with savvy marketers, have designed the newest product to conquer dehydration - fitness water. This new product has taken regular water and added minerals and vitamins, including those vital electrolytes, potassium, sodium and calcium. This new product targets fitness enthusiasts that want to protect against dehydration, but who are looking to keep their calorie count and sugar intake to a minimum, which can help with weight loss goals. Caffeinated drinks should typically be avoided before and during exercise. Caffeinated products increase urine output, which raises the amount of fluid loss. This fluid loss is exactly what we are trying to avoid. Many people drink caffeinated drinks before exercise to obtain extra energy. A suggestion to those who need “the extra energy”— avoid the caffeine and take a vitamin B tablet instead. The vitamin B tablet will give the extra energy desired, without the increased fluid loss. Another product to avoid, especially in relation to hydration, is alcohol. Alcohol, like caffeine, increases urine output, which increases fluid loss. Although most people will not consume alcohol just before exercising, it should be noted that a few drinks the night before a morning workout could have a large negative effect on hydration levels. If you’re planning on exercising the morning after consuming alcohol, drink plenty of fluids, including those necessary electrolytes. Taking in the required electrolytes, as well as satisfactory levels of fluids, will determine your hydration level. It is vital to monitor the body and to continually take in fluids. By the time thirst sets in, the body has already lost at least two percent of its fluid, and dehydration occurs. At any chance possible before and during exercise consume fluids to avoid the harmful consequences of dehydration.

                                  

Along with a balanced diet and regular exercise, multivitamins are a good way to stay in good health. For just pennies a day, they may help lower your risk of cancer, heart disease and osteoporosis as well as prevent some birth defects. When undertaking body weight management, taking a multi-vitamin will keep you strong and healthy. Since you are changing your eating habits in one way or another, you want to make sure you are getting in a good amount of your essential vitamins and minerals. Look to include vitamins: A, D, E & B-Complex (B1, B2, B6, B12), minerals: calcium, magnesium, potassium, copper, manganese, chromium, zinc, iodine, boron, iron & selenium in addition to an anti-oxidant. There are many misconceptions about vitamins and the health benefits they offer.
Vitamins play an important role in keeping the body healthy. However, taking large doses of certain vitamins can actually be harmful. For most people, it is best to get the vitamins our bodies need from eating a variety of healthy, unprocessed foods rather than by taking supplements. Vitamin supplements are frequently misused and taken as a form of medicine to treat ailments such as colds or to counteract lifestyle issues such as stress. Contrary to popular belief, vitamins aren’t drugs or miracle cures. They are organic compounds that participate in various metabolic functions. High-dose supplements should not be taken unless recommended under medical advice. Isolating the ‘active ingredient’ is not the answer Proper balance and adequate levels of essential nutrients is important for a range of complex processes in our body. When vitamins are taken as supplements, they are introduced into the body at levels that could never be achieved by eating even the healthiest of diets. They are also sent in ‘alone’. When they occur in food, vitamins have many other companions to help them along the way. For instance, provitamin A (beta-carotene) in food is accompanied by hundreds of its carotenoid relatives. Simply taking a vitamin pill is not an instant fix for feeling run down or lacking in energy. It is the combination of a whole range of compounds (most of which we probably don’t even know about) in plant foods that gives us the protection. When you artificially remove one of them and provide it completely out of context, it may not be as effective and, in the case of some vitamins, can have negative effects
Recommended dietary intakes
 Many people mistakenly believe that since small amounts of vitamins are good for you, then large amounts must be better. In the case of vitamins, it is better to follow the rule of ‘less is more’. The vitamins A, D, E and K are fat soluble, which means they can be stored in the body. Taking high doses of these vitamins, especially vitamin A, over a long period of time can result in harmful levels in the body unless you have a medically diagnosed deficiency. Some of the water soluble vitamins can also cause side effects in high doses. For instance, vitamin B6 has been linked with nerve damage when taken in large doses. For a healthy adult, if supplements are used, they should generally be taken at levels close to the recommended dietary intake (RDI). High-dose supplements should not be taken unless recommended under medical advice. Deficiencies and illness
The human body is able to store vitamins. The fat soluble vitamins A, D, E and K can be locked away in the liver and body fat and stored for a long time. The water soluble vitamins, including B-complex and vitamin C, are mostly only stored for a shorter period of time. A vitamin deficiency takes weeks or months before it will affect your health. For instance, it would take months of no vitamin C before you developed scurvy. An occasional lapse in good eating will not harm you if your usual diet consists of a wide variety of fresh foods.
Sometimes supplements are needed
 Supplements do have a role to play for some groups of people. For instance, people on long-term restrictive weight loss diets or people with malabsorption problems such as diarrhoea, coeliac disease, cystic fibrosis or pancreatitis can benefit from supplements. Folic acid supplements are strongly recommend for women planning a pregnancy to reduce the risk having a baby with neural tube defects, like spina bifida. People who are advised by their doctor that they need to take vitamin supplements are encouraged to consult an accredited dietitian, who can work with their doctor to provide dietary advice related to the person’s situation. If you need to take a supplement, it is best to take multivitamins at the recommended dietary level, rather than single nutrient supplements or high-dose multivitamins.
The common cold and vitamin C
Many people think that vitamin C helps prevent the common cold. Despite exhaustive research across the world, there is still no strong evidence to prove this. Some studies have shown that taking large doses of vitamin C (more than 1,000mg per day) continuously or at the start of a cold may ease some of the symptoms and the duration, on average, making it about half a day shorter. It does not prevent you catching a cold. You also need to consider the health risks associated with taking large doses of vitamin C. Large doses may cause nausea, abdominal cramps, headaches, fatigue, kidney stones and diarrhoea. It may also interfere with your body’s ability to process (metabolise) other nutrients – for example, it could lead to dangerously raised levels of iron. Excessive amounts of vitamin C in the body can also interfere with medical tests, such as diabetes tests, giving a false result. Adults need about 45mg of vitamin C per day and any excess amount is excreted. Stress, depression and anxiety Some vitamin and omega-3 fatty acid deficiencies can lead to emotional disturbances. However, if you are feeling run down, it is more likely to be due to stress, depression or unhealthy lifestyle habits (such as insufficient sleep or smoking) rather than a vitamin deficiency. Feeling under pressure doesn’t automatically lead to a vitamin deficiency, so taking a vitamin supplement won’t necessarily make the stressful feelings go away. More serious mental illnesses, such as schizophrenia and bipolar disorder, aren’t caused or prevented by vitamins, although a healthy diet and good nutrient intake can help support a person to better cope with their condition.
Vitamin E and heart disease
Vitamin E is widely promoted as a beneficial antioxidant that can help prevent heart disease. Unfortunately, several large-scale reviews have conclusively found no evidence that vitamin E supplements prevent death from heart disease. In fact, there may be greater risk of all-cause death from taking such supplements.
Cancer cures
Vitamin A in large doses does not cure cancer and can be toxic, particularly if taken as pills rather than food. There is some evidence that vitamin E could play a small role in preventing some cancers although, equally, there is evidence that it could hasten the onset of other types of cancer; however, this has not been conclusively proved or disproved. While it is argued by some that megadoses of antioxidants can help with the effectiveness of conventional cancer treatments, such as chemotherapy and radiotherapy, the evidence is far from supporting this. In fact, it has been shown that megadoses of antioxidants can actually interfere with some medical treatments of cancer by helping to protect the cancer cells that the therapies aim to eradicate.
Some research findings
A number of studies into supplement use have shown negative findings. For instance: Vitamin A (beta-carotene) was thought to reduce the risk of some cancers but has been linked to an increase in others, such as lung cancer in smokers, if taken in supplement form. Several long-term studies have shown that prostate, breast and lung cancer risk are not decreased by taking high-dose supplements containing vitamins E or C or selenium. People taking high-dose vitamin E supplements have been found to have higher rates of early death (mortality).
Anti-ageing vitamins
Vitamin E is often singled out as the potential fountain of youth. However, there is no evidence that taking large doses of any vitamin can either stall or reverse the effects of ageing. Neither can any one vitamin restore a flagging sex drive or cure infertility. Vitamins and chronic disease
In developed countries, vitamin deficiency is rare but the inadequate intake of some vitamins is not so rare and has been linked to a number of chronic diseases. These include cardiovascular disease, cancer and osteoporosis. There is ongoing research to study the effects of taking vitamin supplements to prevent chronic disease, and evidence around nutrition and diet is constantly changing. It is important you consult with your doctor before taking vitamin supplements in high doses.
Things to remember
Vitamins are not drugs or miracle cures. Taking large doses of vitamins can be harmful because your body only needs vitamins in very tiny amounts. Eating plenty of fruits, vegetables, whole grains and cereals will give your body most of the vitamins your body needs at the right level and in the right balance. Vitamin supplements can’t replace a healthy diet, but a general multivitamin may help if your diet is inadequate.
People who may need vitamin supplements include pregnant and breastfeeding women, people who consume alcohol in amounts over the recommended level, drug users and the elderly.