Martin Gallagher, M.D., D.C.: I have been a practicing physician for 37 years. During that time, I have directly treated and supervised over 12,000 patient encounters per year. With each patient, I have prescribed a variety of vitamins, minerals, homeopathic medicines, and herbs. I have to date not encountered a single complication, anaphylactic reaction or death. The doses have been well above the RDA's for vitamins and minerals. In fact, the IV treatments include doses of ascorbate (vitamin C) that vary from 10,000 to over 100,000 mg per treatment session.
At a time when the leading cause of death in the US is correctly prescribed medication, we need to embrace, not chastise, nutritional supplements.
Robert G. Smith, M.D.: Most people in modern societies have vitamin and mineral deficiencies because these nutrients are removed by industrial food processing. Vitamin and mineral supplements are effective in preventing deficiencies that cause major illness such as heart disease, cancer, diabetes, arthritis, osteoporosis, dementia, and many others. Supplements of vitamins and minerals, when taken in proper doses large enough to work (For example: vitamin C for an adult at 3,000 - 6,000 mg/day, and much more when stressed or sick), are safe and effective -- and far less expensive than taking prescribed drugs overblown by the medical profession and media.
Michael Janson, M.D.: The standard American diet does not provide even the RDA. Two-thirds of all meals are eaten outside the home, and nearly half of them are in fast food joints. You can't expect this to provide all the necessary nutrients, and many studies show that it does not. A large number of people admitted to hospitals are found to have deficiencies, and the problems worsen in the hospital. Those given supplements have a lower rate of complications, faster discharge from the hospital and fewer deaths. Vitamin companies do not send doctors on expense paid vacations or "seminars," as do the drug companies for prescribing their drugs, and vitamins are safe and cheap. But surely this does not influence pharmaceutical-advertising-paid-for media!
Vitamin E in high doses (800 IU) enhances immunity in healthy elderly subjects. Vitamin C in doses (2,000 mg) far above the RDA (90 mg) significantly reduces allergic rhinitis and asthma and speeds the recovery from airway constriction induced by histamine. Vitamin B1 (thiamine) was used successfully to treat neuralgia, as described in an article published in the Journal of the American Medical Association way back in 1940.
Many people are losing their faith in the medical profession because many doctors are unwilling to accept what is becoming common knowledge: nutrition and nutrient therapies are safer, cheaper and more effective than most other medical treatment. It is clear that most media reporters do not know the current nutrition literature, they do not know the old literature, and they do not know the middle-aged literature. If they do not know the literature, they should not be writing articles.
Michael J. Gonzalez, Ph.D.: Research in Europe has shown that long-term users of antioxidant vitamin supplements have a 48% reduced risk of cancer mortality and 42% lower all-cause mortality.  The media did not bother to mention it. There is in fact overwhelming clinical evidence to justify the use of nutritional supplements for the prevention of disease and the support of optimal health. The Lewin Group estimated a $24 billion savings over 5 years if a few basic nutritional supplements were used in the elderly.  On the other hand, prescription medication kills over 100,000 people a year. 
Thomas Levy, M.D.: There are more politics in modern medicine than in modern politics itself. Today's average physician deserves even less trust than today's average politician, as doctors continue their refusal to allow the scientific data on the profound benefits of vitamins and other antioxidant supplements to reach their eyes and brains. And the staunch support of a press, which collectively no longer has a shred of journalistic or scientific integrity, completes the framing of today's colossal medical fraud. Money always rules the day: properly-dosed vitamins would eliminate far too much of the profit of prescription-based medicine.
William B. Grant, Ph.D.: Modern lifestyles including wearing clothes and sunscreen and working and living largely indoors have led to widespread vitamin D deficiencies. Numerous ecological and observational studies have found correlations between higher solar UVB doses and vitamin D concentrations and reduced risk of many types of cancer, cardiovascular disease, diabetes mellitus, bacterial and viral infectious diseases, autoimmune diseases, falls and fractures, cognitive impairment, and many more types of disease. To compensate for lack of sun exposure, 1,000-5,000 IU per day of vitamin D3 should be taken to raise serum 25-hydroxyvitamin D concentrations to at least 30-40 ng/ml (75-100 nmol/L). These amounts are safe for all but those with granulomatous diseases, who can develop hypercalcemia. 1,000 to 5,000 IU/day of vitamin D is effective in reducing risk of many types of diseases, as shown in a number of randomized controlled trials, such as cancer, falls and fractures, type A influenza, and pneumonia.
W. Todd Penberthy, Ph.D.: Niacin in particular has been shown to provide exceptional benefit in treating cardiovascular disease in clinical trial after clinical trial . By comparison, the popular diabetes drug Avandia was recently found to cause a 43% increase in heart attacks in diabetics.  This came out only after Avandia had already become the most popular diabetes drug in the world! Never underestimate the power of market-driven forces to sell drugs, and books, such as The End of Illness by Dr. Agus, instead of proper information regarding what actually works best.
People are amazed how quickly simply taking supplemental niacin corrects high cholesterol, high triglycerides, low HDL (the good cholesterol) and VLDL. All of these parameters are pushed in the healthier direction because niacin ultimately functions inside the body in over 450 reactions. There is a reason niacin continues as a preferred therapy for doctors in the know, using niacin therapy for over 50 years now. Niacin works better than any drug to correct dyslipidemia.
One thing to always remember is this. You can "prove" that any drug or vitamin does not work if you are not using high enough doses to achieve the correct concentration of the molecule. Furthermore, all biochemical pathways rely on more than one molecule to function properly, so generally one drug/vitamin is not enough for optimal health. Our bodies rely on vitamins, not drugs, to routinely stave off illness by means we often take for granted. Sometimes we need much more of these essential molecules. This is common sense, and it is known as orthomolecular medicine.
James A. Jackson, Ph.D.: For over twenty years, I was the laboratory director of a federally approved clinical reference laboratory. We accepted samples from all the United States and foreign countries. We measured all the fat soluble and water soluble vitamins in blood and urine. It was common to find vitamin deficiencies in both males and females, whether children or adults. The most common vitamin deficiencies were vitamin C and vitamin D3. The clinic's physicians treated the patients with the appropriate vitamins and were monitored by our laboratory. Many were helped by the vitamin replacement treatment, including those with complaints such as headache, joint and muscle pain, chronic fatigue syndrome, and ADHD. We published many of these cases in the Journal of Orthomolecular Medicine. (http://orthomolecular.org/library/jom/index.shtml)
Ian Brighthope, M.D.: Over 70% of Australians consume vitamins on a regular basis. A search of the department of health's database reveals no serious adverse reactions or deaths have occurred in the Australian population over the past ten years from the use of complementary medicines. There is an extreme bias against very low to extremely low risk products by government regulators and health professionals working within and outside the establishment institutions.
Robert Jenkins, D.C., M.S.: I have been in practice for 52 years and have treated thousands of patients with diet and nutritional supplements for numerous health conditions ranging from hypertension, diabetes, hypercholesterolemia, metabolic syndrome, irritable bowel syndrome, and many others. I have yet to experience adverse patient reactions from taking nutritional supplements. I have lectured second year medical students at two medical schools in the Philadelphia, PA area. When I asked those students how much nutritional training they had received, they all held up their hands with the sign of zero. The pharmaceutical industry makes sure medical students are trained in how to prescribe their drugs, while no positive mention is made of nutritional supplements. Why would anyone think that our modern medical doctors are to be considered authorities on nutritional supplementation for health conditions when they are not trained to do so? When this lack of nutritional education is combined with the news media's ignorance of supplements and their benefits, we have "the blind leading the blind."
Gert Schuitemaker, Ph.D.: In the Netherlands, a report of the Dutch Health Council states that less than 2% of the population is eating according to official dietary guidelines.  Moreover, the authorities state that, even if a person is eating according to the dietary guidelines, he is not getting enough vitamin A, D, folic acid, iron, selenium and zinc.  Research in a Dutch hospital showed that 40% of patients at the time of admission were malnourished. So, dietary supplements are necessary. Usually, chronic diseases, developing with increasing age, are treated with medicines, inevitably accompanied with the risk of severe side effects and unnecessary deaths. While the basis of many chronic diseases is a metabolic disturbance and nutritional deficiencies, the best treatment approach is good nutrition, including the use of dietary supplements. The "danger" of vitamins and minerals lies in chronic deficiencies, not in alleged toxic effects. Following the scientific literature on a daily basis, in 30 years, I have not seen any harmful effect from supplements.
Damien Downing, M.D.: The more toxins you are exposed to, the more nutrients you will use up in dealing with them. Every year, we are exposed to more and more toxins, and our DNA has had no time to adapt. Heavy metals such as lead, mercury, fluorine; pesticides including the newer ones like glyphosate ("Roundup"); flame retardants that are even contaminating the Arctic; and hundreds of thousands of other new-to-nature molecules that every human has to deal with. And like it or not, pharmaceutical medications are mostly toxins too.
At the same time, intensive farming, soil depletion and poor diets (often foisted on us for spurious reasons such as fear of cholesterol) mean that it's normal to be deficient now. We are deficient in vitamins, minerals, and other nutrients as well.
What chance does a human have? A much better one if she doesn't buy the hype from big companies, the dogma from pharma-paid scientists, and the bullying from governments. Take your vitamins.
Steve Hickey, Ph.D.: Over the past three centuries, the frequency of deficiency and infectious diseases has been reduced, through improved nutrition and better hygiene. Throughout this time, however, the role of nutrition has been belittled by the authorities. These same authorities now reject the idea that nutritional supplements can prevent our current chronic diseases. Thus, as a result of such authoritarian medicine, we may have replaced the horrors of pellagra, scurvy, and rickets with those of dementia, heart disease, and cancer. If so, it is likely that people in the future will look back with similar dismay on the current and needless destruction of health. How will we answer them, when they ask how could we have allowed this to happen?
Dean Elledge, D.D.S., M.S.: The high-carbohydrate, nutrient-poor diet is a primary contributing factor in dental diseases.  Vitamin D and vitamin C are safe to use in dentistry to help the patient recover from dental diseases. Vitamins in general help reduce inflammation, and antioxidant vitamins reduce the inflammation in periodontal disease. Vitamin supplements improve antioxidant reserves.
Michael Ellis, M.D.: I see so many patients in conventional general practice who are deficient in vitamins. I had one patient who had ended up in a hospital neurosurgical unit only to be found to have severe B12 deficiency. The foods that most people eat are high in sugar, processed, and denatured of essential nutrients. All patients need, at the very least, daily multivitamins.
Ralph Campbell, M.D.: We have had lots of talk of the alleged "toxicity" of vitamins over the decades I have been in pediatric practice. I remain leery of the validity of such accusations. Most are just uninformed regurgitation of poorly designed studies. If alert, a clinician can easily detect vitamin deficiencies, and with experience, quickly spot suboptimal vitamin levels. The medical establishment seems to be increasingly aware of vitamin D, B12 and folic acid deficiency. What is taking the media so long?
Karin Munsterhjelm-Ahumada, M.D.: I have been a physician for 35 years. For the last 20 years, I have worked with combining general medicine with nutritional (orthomolecular) medicine, the practice of preventing and treating disease by providing the body with optimal amounts of substances which are natural to the body, principally vitamins and minerals. I have had good opportunity to compare the results of my work as a GP from the time before I got knowledge of vitamins and minerals as therapeutic substances with the time after I had learned to integrate them in my work with patients. I can today certify that I have seen a great number of very positive results after beginning to integrate vitamins in my clinical work. The results have been particularly fine in neurologic and psychiatric conditions, including schizophrenia, and in hormonal and infectious diseases. During these last 20 years I have not seen severe side effects of orthomolecular substances. On the contrary, I have often been able to decrease the dosage of strong pharmaceutical drugs that carry severe side effects. This has led to a completely new and better quality of life for my patients, and for myself as a doctor.
Conclusion: The old saying remains true: the person who says it can't be done should not interrupt the person successfully doing it. Progressive doctors prescribe vitamins because they work.