With vi­ta­min sup­ple­ments, more isn’t al­ways bet­ter

The Hamilton Spectator - - HEALTH - CARA ROSENBLOOM

The im­mensely prof­itable vi­ta­min in­dus­try de­pends on con­sumers be­liev­ing that more is bet­ter. Al­though sup­ple­ments are ben­e­fi­cial for peo­ple with nu­tri­ent de­fi­cien­cies, there’s lit­tle util­ity in pills, in­jec­tions and in­tra­venous drips if you al­ready get enough vi­ta­mins from your diet. The ex­cess may sim­ply be a waste of money, but it can be­come down­right dan­ger­ous. When should the buyer be­ware?

Food vs. sup­ple­ments

It’s dif­fi­cult to get too much of a sin­gle vi­ta­min from food, ac­cord­ing to Susan Barr, a reg­is­tered di­eti­tian who con­trib­uted to es­tab­lish­ing the Di­etary Ref­er­ence In­takes, which are used across North Amer­ica to es­tab­lish nu­tri­ent needs, as­sess di­etary sta­tus and cre­ate in­dus­try stan­dards. (Those num­bers on nu­tri­tion facts ta­bles? They are based on Di­etary Ref­er­ence In­takes.)

“It’s al­ways best to try to meet your needs for vi­ta­mins by eat­ing a healthy diet,” Barr says. “How­ever, there are some sit­u­a­tions in which a vi­ta­min sup­ple­ment may be rec­om­mended, for ex­am­ple, vi­ta­min D and vi­ta­min B12 for adults over age 50, who may be de­fi­cient in these nu­tri­ents.”

And what about a daily mul­ti­vi­ta­min? Many peo­ple pop a pill as an “in­sur­ance pol­icy” when their di­etary habits are sub­par. A mul­ti­vi­ta­min is safe as long as the dose isn’t ex­ces­sive; don’t take more than one a day.

“When choos­ing a sup­ple­ment, a good gen­eral rule is to look for one that pro­vides no more than 100 per cent of the daily value for any nu­tri­ent,” Barr says. “That can help min­i­mize the po­ten­tial for harm.”

How much is too much?

Wa­ter-sol­u­ble vi­ta­mins, such as vi­ta­min C and a range of B vi­ta­mins, are not stored in the body once in­gested. In­stead, they get ex­creted when you uri­nate.

Even though wa­ter-sol­u­ble vi­ta­mins aren’t stored in the body, ex­ces­sive amounts can still have dam­ag­ing ef­fects:

• High lev­els of vi­ta­min B6 (more than 100 mil­ligrams a day) can cause nerve dam­age, lead­ing to loss of con­trol over bod­ily move­ments.

• More than 2,000 mil­ligrams of vi­ta­min C daily can cause di­ar­rhea and in­crease the risk of kid­ney stones.

• More than 1,000 mi­cro­grams per day of B-vi­ta­min fo­late can in­crease the risk of vi­ta­min B12 de­fi­ciency.

Fat-sol­u­ble vi­ta­mins A, D and E do get stored in the body once in­gested. That means they are more likely to cause tox­i­c­ity than wa­ter­sol­u­ble vi­ta­mins.

“Ex­ces­sive vi­ta­min A can cause birth de­fects, liver prob­lems and skele­tal ab­nor­mal­i­ties, while ex­ces­sive vi­ta­min E can lead to hem­or­rhages and has been as­so­ci­ated with in­creased risk of prostate cancer,” Barr says.

And vi­ta­min D? We need about 600 to 800 in­ter­na­tional units (IU) per day, de­pend­ing on age, but this vi­ta­min is be­ing taken in ex­cess be­cause it’s said to boost im­mu­nity and re­duce cancer risk. Barr says it’s best not to ex­ceed 4,000 IU per day. Higher in­takes may have ad­verse health ef­fects over time, in­clud­ing in­creased risk of car­dio­vas­cu­lar dis­ease and mor­tal­ity.

False prom­ises

Wouldn’t it be amaz­ing if you could hook up to an in­tra­venous (IV) vi­ta­min in­fu­sion that would pre­vent ag­ing, pro­vide bound­less en­ergy and burn body fat? These are claims of pur­vey­ors of IV vi­ta­mins, which flow right into your veins.

“As far as I can tell, there is ab­so­lutely no ev­i­dence to sup­port the IV ther­apy trend,” says Ti­mothy Caulfield, pro­fes­sor and re­search di­rec­tor at the Health Law In­sti­tute of the Univer­sity of Al­berta and au­thor of “Is Gwyneth Pal­trow Wrong About Ev­ery­thing?”

This ther­apy is of­ten mar­keted as a way of al­low­ing vi­ta­mins to by­pass your gut, Caulfield ex­plains, and in­fuse the vi­ta­mins di­rectly into the cel­lu­lar space. “There is a lot of sci­ence-y-sound­ing hand wav­ing, but very lit­tle ac­tual sci­ence,” says Caulfield.

Diet gu­rus ped­dle sim­i­lar claims, promis­ing that vi­ta­min B12 shots will pro­duce rapid weight loss. Of course, the in­jec­tions are part­nered with a low-calo­rie diet. Luck­ily, an ex­cess of vi­ta­min B12 won’t cause harm, ex­cept to your wal­let.

“The pub­lic seems to love vi­ta­mins,” Caulfield says. “We can’t for­get that it is a huge in­dus­try and there are many voices in pop­u­lar cul­ture push­ing the more-is-bet­ter mes­sage. Our body needs the cor­rect amount, which, for most of us, can be ob­tained by eat­ing a healthy diet.”

Reg­is­tered di­eti­tian Cara Rosenbloom is the coau­thor of “Nour­ish: Whole Food Recipes Fea­tur­ing Seeds, Nuts and Beans.” Wash­ing­ton Post

GETTY

Al­though sup­ple­ments are ben­e­fi­cial for peo­ple with nu­tri­ent de­fi­cien­cies, there’s lit­tle util­ity in them if you al­ready get enough vi­ta­mins from your diet.

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