Does coffee consumption pose health risks? In a word: No

The Evidence:

Crippa, A., Discacciati, A., Larsson, S. C., Wolk, A., & Orsini, N. (2014). Coffee consumption and mortality from all causes, cardiovascular disease, and cancer: A dose-response meta-analysis. American Journal of Epidemiology, 180, 763-775. doi: 10.1093/aje/kwu194

What did the meta-analysis look into?

The meta-analysis investigated whether drinking coffee is related to disease and death from ‘any cause’, death from cardiovascular disease (CVD), and death from cancer. The study compared people that regularly drunk coffee to those that rarely or never drank coffee, with a focus on the dose consumed. The following questions were answered:

(1) Is drinking more coffee associated with greater risks and death?

(2) What dose of coffee might be good or bad for health?

The meta-analysis synthesized evidence from 21 studies, including a total of 121,915 deaths and 997,464 people from the United States, Europe, and Japan, who were followed between 7.7 years and 24 years.

What did the evidence suggest about the relationship between coffee consumption and death from ‘any cause’?

The association between coffee and all-cause mortality was ‘non-linear’, which, essentially, means a “predictable but complicated” relationship. Specifically:

Drinking 1 cup of coffee per day was associated with the highest risk of all-cause mortality.

Drinking 4 cups a day were associated with the lowest risk of all-cause mortality (16% risk reduction).

What did the evidence suggest about the relationship between coffee consumption and death from CVD?

The association between coffee and CVD mortality was also found to be ‘non-linear’.

Specifically:

Drinking 6 cups of coffee per day was associated with the highest risk of dying from CVD.

Drinking 3 cups of coffee per day was associated with the lowest risk of dying from CVD (21% risk reduction).

What did the evidence suggest about the relationship between coffee consumption and death from cancer?

The association between coffee consumption and cancer mortality was not statistically significant, which means that there was “little if any credible evidence” for said association.

The take-home message

Compared to people that rarely (or never) drink coffee, those who drink 3-4 cups of coffee per day are likely to reduce their risk of dying from “any cause”, including from cardiovascular disease. Also, coffee consumption does not appear to be related to cancer mortality. The reasons why 3-4 cups per day may be protective to health are not extremely clear but could be due to anti-oxidant and anti-inflammatory coffee compounds. Broadly speaking, regular and long-term consumption of 3-4 cups of coffee offers noteworthy health protective benefits (but consumption of < 3 cups or >5 cups does not). Coffee is often being considered as potentially unhealthy but this has not been supported by meta-analytic studies.

Does fat restriction protect from heart disease and related deaths? In a word: No.

The Evidence

Harcombe, Z., Baker, J. S., Cooper, S. M., Davies, B., Sculthorpe, N., DiNicolantonio, J. J., & Grace, F. (2015). Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: A systematic review and meta-analysis. Open Heart, 2:e000196. doi: 10.1136/openhrt-2014-000196

What did the meta-analysis look into?

The meta-analysis investigated whether the low-fat recommendations were supported by evidence when they were issued (back in 1977 in the USA, and in 1983 in the UK). Today, dietary recommendations restrict “all-fat” consumption to 30% of daily food calorie intake, and “saturated fat” to 10%. This was based on the assumption that fat restriction would reduce coronary heart disease (CHD) and related deaths.

Specifically, the meta-analysis looked at:

(1) The benefits of vegetable oil consumption and fat restriction on people with CHD.

(2) The benefits of replacing saturated fats (those that are solid in room temperature and typically found in red & deli meats, dairy, baked goods) with vegetable oils, in people with CHD.

The meta-analysis synthesized evidence from 6 experimental studies, including a total 2467 male participants, out of which 740 had died from a variety of reasons, and 423 had died from CHD.

What did the evidence suggest about the relationship between fat restriction and “all-cause” deaths?

Reducing fat consumption and replacing saturated fats with vegetable oils did not substantially decrease death from “all causes”.

What did the evidence suggest about the relationship between fat restriction and deaths from CHD?

Reducing fat consumption and replacing saturated fats with vegetable oils did not substantially decrease death from CHD.

What did the evidence suggest about the relationship between fat restriction and cholesterol levels in the body?

Cholesterol levels dropped regardless of the type and amount of fats consumed, but dropped more in those who restricted their (saturated) fat consumption.

The take-home message

Reducing of “all fat” and especially saturated fat consumption does not appear to protect from CHD, death from CHD, or “all-cause” deaths. While cholesterol dropped more in those who restricted (saturated) fat consumption, this did not also lower CHD or “all-cause” deaths. High cholesterol may not be the cause of CHD. Dietary recommendations (restricting “all-fat” consumption to 30% of daily food calorie intake, and “saturated fat” to 10%) were not based on the evidence when issued. Broadly speaking, claims about the dangers of fat consumption on CHD and death may not be warranted.

Are organic foods substantially better for our health?

In a word: No.

The Evidence

Smith-Spangler, C., Brandeau, M. L., Hunter, G. E., Bavinger, J. C., Pearson, M., Eschbach, P. J., ... & Olkin, I. (2012). Are organic foods safer or healthier than conventional alternatives?: A systematic review. Annals of Internal Medicine, 157, 348-366. doi: 10.7326/0003-4819-157-5-201209040-00007

What did the meta-analysis look into?

This meta-analysis investigated whether organic foods are substantially healthier (more nutritious and safer) than conventional foods. Specifically, the study compared the nutrients, bacteria, fungi, or pesticides found in organic and conventional foods (vegetables, fruits, grains, meat, poultry, eggs, and milk), and in people eating the foods. The meta-analysis synthesized evidence from 17 studies, including a total of 13 806 people (pregnant and non-pregnant women, children, and non-pregnant adults) from Europe and the United States.

How did the type of food affect the health of pregnant women and children?

There was no indication that eating either type of food contributed to the development of ill-health conditions, including wheezing, eczema, asthma, and other allergic reactions.

How did the type of food affect the health of non-pregnant adults?

Vitamin and antioxidant levels were similar in organic and conventional food eaters. Also similar was the function of the immune system, the levels of LDL cholesterol (the so-called "bad cholesterol"), and the quality of the sperm. Interestingly, there was evidence indicating that the consumption of organic meat in the winter increased the risk of campylobacter infection, which is a common food-borne illness.

What did the evidence suggest about the vitamin and nutrient levels in the foods?

Vitamin content was similar in organic and conventional vegetables, fruits, and meats. Protein and fat content was similar in organic and conventional milk. Total fatty acid content was similar in the breast milk of mothers who ate large amounts of organic dairy and meat, and in the milk of mothers who consumed small amounts of organic dairy and milk. However, two nutrients (phosphorus & phenols), were found in substantially higher levels in organic produce. Beneficial omega 3 fatty acids were found in higher levels in organic chicken and organic milk.

What did the evidence suggest about the contaminants in the foods?

Pesticides were detected in both organic and conventional samples (in 7% of the organic samples and 38% of the conventional ones). The risk of finding bacteria resistant to antibiotics was 33% higher in conventional chicken and pork. Total bacteria and heavy metal count (cadmium or lead) was similar in both types of foods. The evidence was unclear for fungal toxins. Only 3 out of the 17 studies detected levels of contamination that exceeded maximum allowed limits.

The take-home message

Compared to conventional foods, organic foods do not appear to provide additional health benefits, even though organic produce may expose consumers to fewer pesticides, and organic chicken/pork may expose consumers to fewer antibiotic-resistant bacteria. Broadly speaking, claims of the superiority of organic foods may be exaggerated.