By: Dr. Geoffrey Modest
There are new draft nutrition guidelines from the US Dept of Health and Human Services and the Dept of Agriculture (see here). No huge changes, other than the comment “cholesterol is not considered a nutrient of concern for overconsumption“. Other points:
–vitamin D, calcium, potassium and fiber are underconsumed across the entire US population
–iron is underconsumed for adolescent and premenopausal females
–sodium is overconsumed across the entire US population
–saturated fat is overconsumed and may pose the greatest risk to those > 50 years old
–caffeine intake does not exceed what are currently considered safe levels for any age group
–fruits, vegetables, whole grains, dairy foods are under recommended goals for vast majority of US population. Fruit intake is low but stable from 2001-2010, vegetables have declined.
–refined grains, solid fats, and added sugars are more consumed than recommended. added sugars have decreased a bit from 2001-2010
–young kids consume recommended amounts of fruit and dairy, but this drops off as kids reach school age
–rates of overweight and obesity are extremely high and have persisted for more than 25 years in children, adolescents and adults
–65% of adult females and 70% of adult males are overweight or obese
–rates of overweight and obese are highest in those >40yo, and vary by race/ethnicity
–same is true for abdominal obesity
–1 in 3 youth aged 2-19 is overweight or obese
–of note,from 2009-2012 the percent of males >20yo who are overweight, obese, and extremely obese has declined a tad. For women, these are still slowly increasing
Comments:
–cholesterol: it has long been known that the hypercholesterolemic effect (ie, increase in serum cholesterol) of eating cholesterol is about 1/3 that of eating saturated fats and about 1/9 of that of eating trans fats. Several very large observational studies have not found that eating foods high in cholesterol is much of a cardiovascular risk factor. Also, as a perspective, only a small minority of circulating cholesterol (about 20%) is from diet, most is from genes….
–saturated fats: there are some recent data that, in terms of cardiac outcomes, plant-derived saturated fats are much better than animal-derived ones
–trans fats: the worst. Finally, there are significant public health initiatives to decrease their use.
–sodium: for IOM (institute of medicine) report on sodium intake (which proposes a less-aggressive approach, but still targets much lower than current consumption), see blog
–potassium: see appended blog below from 4/22/13. Seems like this is a really important clinical target for intervention.
–caffeine: good news that we don’t have to cut back….
blog from 4/22/13:
BMJ did a systematic review of studies on potassium intake and blood pressure response/clinical outcomes (see BMJ 2013;346:f1378). looked at 22 RCTs (1600 people) and 11 cohort studies (127K people). assessed relation between potassium intake and blood pressure, lipids, catecholamines and renal function in the RCTs and all cause mortality, cardiovascular dz, stroke or CAD in the cohort studies. Results:
–BP is lowered by potassium intake, but only in hypertensive patients
–in those taking 90-120 mmol/d of potassium, the blood pressure decreased 7.2/4.0 mmHg
–no significant further decrease of BP if potassium intake >120 mmol/d
–all pts with hypertension benefitted by potassium supplementation (does not seem to matter if by food or supplements, whether on BP meds or not), though those with high Na intake (>4gm/d, which is pretty normal in our society), benefitted the most
–in kids, cohort data found that high K intake associated with less increase in BP over time (1mm Hg systolic BP difference/yr)
–for stroke, 24% decrease in those with higher potassium intake overall, 30% decrease in those with potassium intake in the 90-120 mmol/d range. No diff in cardiovasc events
–no change in renal function, serum lipids, or catecholamine levels
Background: Overall, potassium intake is much lower than it used to be (was over 200 mmol/d in remote ancestors, decreased in modern society dramatically to 70-80 mmol/L range in many countries, likely attributed to eating fewer unprocessed foods now and esp decreased fruits/veges/legumes. Recommended daily intake of potassium in US is 120 mmol/d. Older epidemiologic studies found relationship between low potassium and high BP and stroke. Intervention data have been mixed. So, present study initiated by WHO to evaluate.
The 2011 NICE guidelines on hypertension, which I personally think are the best/most complete/most up-to-date around, evaluated the data and were pretty restrictive in what they included. They noted that there were inconsistencies in the results of high potassium intake on blood pressure, concluding that there were insufficient data to recommend a higher potassium intake as part of therapy.
So…. as with many of these non-pharmacological interventions, it makes sense to encourage patients strongly to eat non-processed foods, and esp to eat fresh fruits and vegetables/legumes. Helps the blood pressure and probably everything else. I would be a bit reluctant to simply give potassium supplements, though would recommend the fruits/veges (perhaps one of the reasons the DASH diet works is that it is relatively high in potassium). And, one other, tangential and unproved (i.e., personal) feeling is that diuretics may not be the best first-line med (supported by recommendations by NICE), that this may be especially true in those with low K intake, and when diuretics seem indicated in pts wtih low K intake, consider the combo K-sparing (and Mg-sparing, by the way) meds, such as triamterene-HCTZ.
by the way, i know that many of us see pts with very high blood pressures, but it is important to remember that the vast majority of hypertensive patients have only small BP elevations. the data in the UK is that lowering blood pressure 5mmHg would decrease hypertension by 50%. lowering BP by 2mmHg in the US would decrease cardiac events by 67K and stroke by 35K. so, the level of decrease by raising K intake as above would have really profound effects.