The Importance of Vitamins in Our Diet

Tablets. (iStockphoto/Thinkstock)
Tablets. (iStockphoto/Thinkstock)

In general, most people know the importance of vitamins in our diet. But many people do not know which vitamins are really important in maintaining good health.

I would like to revisit an article I had discussed about ten years ago on this topic. Not much has changed since. The topic was also discussed in a Clinical Practice article in the New England Journal of Medicine (NEJM) titled, “What vitamins should I be taking, doctor?”

Medical teaching says that a healthy individual, who eats a good diet, does not require vitamin supplements. He should be able to meet his vitamin needs from his healthy diet. But the public interest in vitamin supplements is enormous – sometimes due to misguided reasons. Almost 30 percent of our population takes vitamin supplements. And there is no control over it.

Because the food we eat contains too many nutrients, it would be almost impossible to conduct double blind trials to see if vitamins do have improved clinical outcomes. Also the users of vitamin supplements may have healthier lifestyles or behaviours than nonusers. This would distort any clinical trial results.

The good thing about vitamin supplements is that there is greater likelihood of good than harm and cost of supplements is not that high so the authors of the article in the NEJM recommend the following vitamin supplements for healthy individuals. There is substantial evidence that higher intake of:
1. folic acid (400 ug/day),
2. vitamin B6 (2 mg/day),
3. vitamin B12 (6 ug/day), and
4. vitamin D (400 IU/day) will benefit many people, and a
5. a multivitamin will ensure an adequate intake of other vitamins for which the evidence of benefit is indirect.

The authors say a multivitamin is especially important:
-for women who might become pregnant
-for persons who regularly consume one or two alcoholic drinks per day
-for the elderly, who tend to absorb vitamin B12 poorly and are often deficient in vitamin D
-for vegetarians, who require supplemental vitamin B12 and
-for poor urban residents, who may be unable to afford adequate intakes of fruits and vegetables.

It should be noted that recent recommendation for vitamin D suggests all adults should take 1,000 to 2,000 IU daily. The upper level for safe vitamin D intake has not been well defined but is probably as high as 250 μg (10,000 IU) daily but in clinical practice, supplementation with this dose of vitamin D is rarely required.

Physicians who encourage their patients to take vitamin supplements should also educate their patients regarding healthy lifestyle and about healthy nutritious diet. Foods contain many additional important components, such as fiber and essential fatty acids and vitamin pills cannot be a substitute. Vitamin pills do not compensate for the massive risks associated with smoking, obesity, or inactivity, say the authors of the NEJM.

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Eat Fruits and Vegetables to Produce Healthier Sperm

A sperm fertilizing an egg. (iStockphoto/Thinkstock)
A sperm fertilizing an egg. (iStockphoto/Thinkstock)

A study published in Fertility and Sterility reported men who consume a high amount of certain nutrients may produce healthier sperm than men who do not. The study also found this effect to be more pronounced in older men.

Dr. Andrew Wyrobeck and his colleagues from Lawrence Berkeley National Laboratory, Berkeley, California determined dietary micronutrient intake among 80 individuals aged 22 to 80 years. Examples of micronutrients are vitamin C, vitamin E, and zinc. These nutrients are required by the body in small quantities for a whole range of physiological functions. The human body does not produce these micronutrients. Sperms from these individuals were also analysed.

The study found men with a higher intake of vitamin C, vitamin E, folate, and zinc produced sperm that had significantly less DNA damage than men who consumed lower amounts. Analysis showed that older men with an intake below that of the population’s median levels for vitamin C, vitamin E, and zinc (but not β-carotene or folate) had significantly more sperm DNA damage compared with all other groups, including older men with above median intakes.

What does this mean? It means older men who are planning to father a child in the near future should start eating a healthy diet if they are not doing so already. Older fathers, with DNA-damaged sperm, may be contributing to the increasing rates of autism, schizophrenia and other diseases among children and adolescents.

Researchers say consuming micronutrients such as vitamin C, E, folate and zinc helps turn back the clock for older men. The analysis revealed that men older than 44 who consumed the most vitamins and micronutrients had 20 per cent less sperm DNA damage compared to men their own age who consumed the fewest nutrients.

In younger men, a higher intake of micronutrients didn’t improve the quality of the DNA in their sperm. The benefit was observed solely among the older men. But, of course, they are the ones most vulnerable to sperm DNA damage – and therefore have the most to gain from an improved diet.

Future studies are needed to determine whether increased antioxidant intake in older fathers will improve fertility, reduce risks for genetically defective pregnancies, and result in healthier children, concludes the team.

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Salty Advice About Dietary Salt

A spilled salt shaker. (iStockphoto/Thinkstock)
A spilled salt shaker. (iStockphoto/Thinkstock)

None of us are strangers to table salt. Everytime you eat something, you probably make a remark regarding the amount of salt in the food. Some people may think it is just right, some may find it too salty and some may feel extra salt is required.

Our body contains many salts. Table salt (sodium chloride) is a major one making up around 0.4 per cent of the body’s weight at a concentration pretty much equivalent to that in seawater. Somebody has calculated a 50 kg person would have around 200 gm of sodium chloride in his body. That makes around 40 teaspoons.

We continually lose salt when we lose water from our body as salt is in a solution. So when we are sweating, vomiting, having diarrhea or voiding water by act of urination, we are losing salt. Salt cannot be made in our body so we have to replenish it otherwise there can be serious consequences.

Salt is needed to maintain our blood volume and blood pressure. Sodium is also needed for nerves and muscles to work properly. Low levels of body sodium can make our brain swell and cause confusion.

Too much sodium is bad for us as well. Excessive consumption of sodium can increase blood pressure, and that salt is a major determinant of population blood pressure levels. Some research estimates suggest the numbers of deaths averted by moderate reductions in population salt consumption would be at least as many as those achieved by plausible reductions in population smoking rates (CMAJ June 12, 2012).

The fast food industry is making its own contribution towards increasing the general population’s salt intake. Fairly large population is relying on fast food industry to provide their daily food needs. Fast food tends to be more energy dense, contain more saturated fat and salt, contain fewer micronutrients and be eaten in larger portions than other foods, says the CMAJ article.

Fast food items such as fried potatoes, pizzas and sugar-sweetened soft drinks typically provide between one-third and one-half of daily energy intake but less than one-quarter of most micronutrients.

Now what? Too much or too little salt in the diet can lead to muscle cramps, dizziness, or electrolyte disturbance, which can cause neurological problems, or death. Generally, more emphasis is given to the evidence showing an association between salt intakes and blood pressure among adults. We also know reduced salt intake results in a small reduction in blood pressure. Evidence suggests that high salt intake causes enlargement of the heart and swelling of the legs.

There is a clear scientific evidence that a modest and long term reduction in population salt intake can result in a lower population blood pressure, and a reduction in strokes, heart attacks and heart failure.

Then what are we waiting for? Most of us consume more salt than we need. General recommendation is no more than six grams (about one teaspoon) of table salt a day. This includes salt used in cooking and at the table. If you have high blood pressure or heart disease then less than two grams of table salt per day will be helpful. Are you willing to try that?

So, how is your food tasting today?

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How much vitamin D do you need daily to prevent fractures?

A vitamin capsule. (iStockphoto/Thinkstock)
A vitamin capsule. (iStockphoto/Thinkstock)

Basking in the sun is one way to obtain vitamin D

Basking in the sun is one way to obtain vitamin D although the risk of skin cancer increases. Other sources of vitamin D are fortified dairy products, fatty fish and egg yolks.

Answer to this question appears in an article in the New England Journal of Medicine (NEJM) published in July, 2012. The authors examined the relationship between vitamin D supplementation and fracture reduction.

They looked at 11 double-blind, randomized, controlled trials of oral vitamin D supplementation (daily, weekly, or every 4 months), with or without calcium, in persons 65 years of age or older. The goal was to look for the incidence of hip and any nonspinal fractures.

The study included 31,022 persons (mean age, 76 years; 91 per cent women) with 1111 incident hip fractures and 3770 nonspinal fractures.

When they looked at a subgroup of participants by actual intake of vitamin D, they found reduction in the risk of fracture was shown only at the highest intake level (median, 800 IU daily; range, 792 to 2000), with a 30 per cent reduction in the risk of hip fracture and a 14 per cent reduction in the risk of any nonspinal fracture.

“Benefits at the highest level of vitamin D intake were fairly consistent across subgroups defined by age group, type of dwelling, baseline 25-hydroxyvitamin D level, and additional calcium intake,” says the NEJM paper.

The conclusion of the study was that high-dose vitamin D supplementation (≥800 IU daily) was somewhat favorable in the prevention of hip fracture and any nonspinal fracture in persons 65 years of age or older.

As we know, vitamin D is a nutrient that helps the body use calcium and phosphorous to build and maintain strong bones and teeth. Vitamin D is unique in that it can be synthesized by the body after exposure to ultraviolet rays from sunlight.

Too much vitamin D can cause too much calcium to be deposited in the body, which can lead to calcification of the kidney and other soft tissues including the heart, lungs and blood vessels. But it is hard to define what is too much. Some expert recommend daily intake of 1000 to 2000 IU of vitamin D to prevent certain types of cancers.

Health Canada’s recommendation for daily dietary intake of vitamin D in adults age 70 and over is 800 IU (20 mcg). This is based on the assumption that there is minimum of exposure to sunlight. The major sources of vitamin D are fortified foods. In Canada, cow’s milk and margarine must be fortified with vitamin D. The only natural sources of vitamin D in the Canadian food supply are fatty fish and egg yolks.

Many people meet at least some of their vitamin D needs through exposure to sunlight. Although there is some risk of skin cancer. But you never know how much vitamin D you are getting through sun exposure. It all depends on the season, time of day, cloud cover, smog, skin pigmentation, and sunscreen use.

Daily intake of vitamin D recommendation depends on a person’s age. Talk to your doctor or see Health Canada website for more details. But do not forget to drink your milk everyday.

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