Are dairy prod­ucts re­ally dan­ger­ous or a su­per­food?

The long-held be­lief that dairy prod­ucts in­crease the risk of heart dis­ease still per­sists, even though ev­i­dence sug­gests oth­er­wise

The Irish Times - Tuesday - Health - - Front Page - Danielle Bar­ron

Is dairy bad for our health? Or are milk and but­ter the new superfoods? The link be­tween milk and mor­tal­ity is com­pli­cated. A re­cent con­fer­ence held in Seville, Spain, looked at the role of dairy in sus­tain­able di­ets, and more specif­i­cally, the im­pact of dairy con­sump­tion on over­all health. Dr Ian Givens, pro­fes­sor of food-chain nu­tri­tion at Read­ing Univer­sity, was there to dis­cuss his re­search on whether dairy prod­ucts in­crease the risk of death from any cause and from ei­ther se­ri­ous heart prob­lems or car­dio­vas­cu­lar dis­ease.

“There’s been a lot of public­ity over the last five to 10 years about how sat­u­rated fats in­crease the risk of car­dio­vas­cu­lar dis­ease and a be­lief has grown up that they must in­crease the risk, but they don’t al­ways,” says Dr Givens.

Sev­eral ma­jor re­views of the ev­i­dence link­ing dairy and car­diometabolic dis­eases, namely car­dio­vas­cu­lar dis­ease and di­a­betes, have been pub­lished in re­cent years, sev­eral of which Prof Givens has been in­volved in writ­ing. “Broadly speak­ing, these tell us that the rel­a­tive risk of all-cause mor­tal­ity in car­dio­vas­cu­lar dis­ease in re­la­tion to milk con­sump­tion over­all is neu­tral,” he tells The Ir­ish Times.

“There is no ev­i­dence of an in­creased risk, and on the other hand, one study look­ing at cheese and its re­la­tion to car­dio­vas­cu­lar risk saw a sig­nif­i­cant re­duc­tion in risk. We have seen this over the past 10 years, with nega­tive as­so­ci­a­tions ob­served be­tween milk con­sump­tion and stroke, as well as cheese and stroke, although the lat­ter is not as sig­nif­i­cant.”

Yo­ghurt con­sump­tion and di­a­betes

In Givens’ opin­ion, the most in­ter­est­ing, and pos­si­bly the most im­por­tant, piece of ev­i­dence is that which shows a direct as­so­ci­a­tion be­tween yo­ghurt con­sump­tion and di­a­betes. “Fer­mented dairy prod­ucts seem to be as­so­ci­ated with a re­duced risk of di­a­betes. I think this is an area that we should prob­a­bly bring more em­pha­sis on, whether we try to use yo­ghurt more in a pre­ven­tive role, or whether it can also be ben­e­fi­cial in a treat­ment role, but it is some­thing that we should be cap­i­tal­is­ing on,” he says.

Givens also sought to shed some light on the im­age of sat­u­rated fat as the real en­emy in the war against heart dis­ease. He says this be­lief stems from stud­ies car­ried out in the mid-20th cen­tury, which showed sat­u­rated fat el­e­vated blood choles­terol. As high lev­els of choles­terol were known to be as­so­ci­ated with an in­creased risk of car­diac dis­ease, sci­en­tists and food re­searchers thus as­sumed that sat­u­rated fat was a direct route to heart dis­ease. Hastily drawn up di­etary guide­lines urged peo­ple to cut down on sources of sat­u­rated fat – a be­lief that still per­sists to this day.

“For many peo­ple, dairy prod­ucts are still the big­gest source of sat­u­rated fats in their di­ets,” says Givens.

Yet, the ev­i­dence sug­gests the source of sat­u­rated fat may play a big­ger role – stud­ies have shown meat is as­so­ci­ated with an in­creased risk of heart dis­ease, whereas dairy is not. “This sug­gests dairy and sat­u­rated fat may not al­ways have the ef­fect you might pre­dict from the old data,” he says.

An­other area that has re­ceived a lot of at­ten­tion is that of the so-called “dairy ma­trix ef­fect”. The food sci­en­tist ex­plains that this was a “very real ef­fect”, whereby re­duc­tions in choles­terol are ob­served in peo­ple af­ter con­sump­tion of but­ter or cheese.

“It seems to be an ef­fect of cal­cium ac­tu­ally re­duc­ing the amount of fat that ar­rives in the gut and is ab­sorbed, and that is prob­a­bly one of the fac­tors in­flu­enc­ing this choles­terol re­sponse we see, although it is thought that this only ex­plains about 50 per cent of this ef­fect.”

Pub­lic per­cep­tion

The pub­lic per­cep­tion of sat­u­rated fat clog­ging the ar­ter­ies still per­sists. Why hasn’t this nar­ra­tive changed?

Givens blames the me­dia. “Years and years of be­ing told that sat­u­rated fats in­crease choles­terol, and that in­creases the risk of heart dis­ease, will not be wiped out overnight. It’s not com­pletely un­true, but what the pub­lic haven’t been made aware of is that there are sit­u­a­tions where it is un­true. The me­dia hasn’t spent the time ex­plain­ing the more com­pli­cated ar­eas – for ex­am­ple, there is good choles­terol and bad choles­terol but that has not been made clear.”

Givens be­lieves the fo­cus should not be on our con­sump­tion of sat­u­rated fat, but rather what has re­placed it in our di­ets. The PURE study, which made head­lines over the world in sum­mer 2017, looked at the as­so­ci­a­tion be­tween dif­fer­ent fats and car­bo­hy­drate in­take in re­la­tion to the risk of heart dis­ease.

Fatty acids

“What stands out from the study is the ef­fect of in­creas­ing the amount of en­ergy from car­bo­hy­drates. It showed if you re­place sat­u­rated fatty acids with car­bo­hy­drates, the risk in­creases, and this is par­tic­u­larly the case with more re­fined car­bo­hy­drates.

“Over the past 20 to 30 years, there has been a de­cline in sat­u­rated-fat con­sump­tion, but it has prob­a­bly mainly been re­placed by car­bo­hy­drates,” Givens ex­plains. “In di­etary guide­lines, less em­pha­sis on fat and prob­a­bly a lit­tle more em­pha­sis on re­strict­ing car­bo­hy­drate might im­prove health. This mes­sage is not fully ap­pre­ci­ated.”

In­deed, the re­cent trend to­wards fo­cus­ing on the sus­tain­abil­ity of dif­fer­ent di­ets is not wel­comed by Givens. “So-called sus­tain­able di­ets must be as­sessed for func­tion­al­ity, which goes be­yond tra­di­tional nu­tri­ents com­po­si­tion, be­cause you can’t pre­dict the ef­fect on blood pres­sure, or ar­te­rial stiff­ness, or on blood glu­cose, simply from nu­tri­ent com­po­si­tion.

“There should be some recog­ni­tion that trade-offs need to be made, in terms of sus­tain­abil­ity from a health point of view and sus­tain­abil­ity from an en­vi­ron­men­tal point of view.”

Years and years of be­ing told that sat­u­rated fats in­crease choles­terol, and that in­creases the risk of heart dis­ease, will not be wiped out overnight

PHO­TO­GRAPH: ISTOCK

Su­per foods, or should dairy prod­ucts be avoided?

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