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Nutrition Research Findings & Your Patients

Evidence for Mediterranean Diet Compelling

Though diet is not often talked about in medicine, findings from the largest randomized trial to date on the Mediterranean (‘Med’) diet, make this way of eating worth mentioning to patients.

In this trial (1) of more than 7,400 men and women at risk of cardiovascular disease (CVD), individuals were randomly assigned to 3 different diets: two were Med-diets enriched with either nuts or extra-virgin olive oil, and the third was a low-fat diet. In the two Med-diet groups, there was a significant reduction in the primary endpoints of major cardiovascular events, namely death, heart attack or stroke. Particularly notable was the risk reduction seen in stroke – a significant 49%.

Why is the trial noteworthy? It was well conducted and demonstrates that the Med-diet has a role in primary prevention of CVD (benefit in secondary prevention of CVD was shown in a previous trial). In addition, the results were dramatic. Investigators halted the study early when an interim analysis revealed that the low-fat control group was at a clear-cut disadvantage.

Study participants did not have to restrict their calorie intake, and compliance with the Med-diets during the median 4.8 years of follow-up was good. This suggests that the Med-diet is user-friendly to adopt.

The Med-diet is rich in fresh fruits and vegetables, seafood, whole-grains and mono-unsaturated fats (the type found in olive oil). All groups in this study were able to cut back on meats, sweets, dairy and alcohol. However, the main difference between interventions was that the Med-diet group ate fewer carbohydrates (especially sugar and processed carbs) and more fats (mostly from olive oil), fruit, beans, and nuts.

Relevant to ocular health, the diet is rich in vegetables (leafy green) and fish, sources of lutein, zeaxanthin, and the long-chain fatty acids EPA and DHA. These nutrients have been linked to a lower risk of AMD development or progression.

Berries Reduce Heart Attack Risk in Women

If the Med-diet encourages consumption of fruit, the findings of a study (2) from Harvard suggest that blueberries and strawberries are one of the fruits to choose on a regular basis.

Data was analyzed from 93,600 women participating in the Nurses’ Health Study II, where dietary data was collected every four years. During the study, 405 heart attacks were documented.

The highest consumption of the two berries – 3 or more servings weekly – was associated with a one-third reduction in risk of heart attack. This risk reduction was seen even in women who otherwise ate a diet abundant in other fruits and vegetables.

The researchers attribute the apparent benefits to the berries’ anthocyanin content. In another recent study (3), 320 mg of purified anthocyanins daily for 6 months was reported to significantly reduce the inflammatory bio-marker C-reactive protein and soluble vascular cell adhesion molecule-1 compared to placebo in 150 subjects with elevated cholesterol levels.

Beware of Grapefruit-Drug Interactions

A review (4) of grapefruit – drug interactions, concludes that the number of oral drugs that react adversely with this fruit is higher than previously thought, nearly half of those drugs may be associated with potentially serious adverse effects, and interactions occur at lower levels than formerly suspected (as little as 7-8 oz. of juice).

Of the more than 85 common medications known or predicted to interact, many were anti-infective, anti-lipidemic (e.g. statins), and GI agents. The culprits in grapefruit are the furanocoumarins, which irreversibly inhibit the cytochrome P450 enzyme CYP3A4 in the GI tract. These compounds are also found in Seville oranges (but not navel or Valencia), limes and pomelos. Read more

References

1. Estruch R et al. Primary prevention of cardio-vascular disease with a Mediterranean diet. NEJM [Epub Feb. 25, 2013].
2. Cassidy A et al. High anthocyanin intake is associated with a reduced risk of myocardial infarction in young and middle-aged women. Circulation 127:188-96, 2013.
3. Zhu Y et al. Anti-inflammatory effect of purified dietary anthocyanin in adults with hypercholesterolemia: A randomized controlled trial. Nutr Metab Cardiovasc Dis Epub Aug 7, 2012.
4. Bailey DG et al. Grapefruit-medication interactions: forbidden fruit or avoidable consequences. CMAJ 185:309-16, 2013.