Nutrigenetic Interactions and Caffeine Intake: Is there a Relationship?

Nutrigenetic Interactions and Caffeine Intake: Is there a Relationship?

Identifying slow caffeine metabolizers (e.g. based on CYP1A2 polymorphisms) and reducing caffeine intake may reduce markers associated with the risk of hypertension, prediabetes and kidney disease. 

A 2023 systematic review examining associations between genetics and coffee intake on cardiometabolic outcomes suggested that single nucleotide polymorphisms (SNPs) of the CYP1A2 (rs762551) and ADORA2A (rs5751878) genes can increase fasting glucose and blood pressure response following caffeine consumption, particularly in the short term; however, the effects on cardiovascular disease (CVD) are uncertain due to conflicting findings. 

A 2023 cohort study found an association between heavy coffee intake (>3 cups /day) and the development of kidney disease only in individuals who were slow caffeine metabolizers (i.e with AC and CC genotypes of CYP1A2 (rs762551)). 

Grade of Evidence C

SNPs are the most common type of genetic variation. Each SNP represents a difference in a single DNA nucleotide. The rsID number is used to identify a specific SNP.

Individuals with AC and CC genotypes of CYP1A2 (rs762551) are considered slow caffeine metabolizers, and individuals with the AA genotype are considered fast metabolizers. In the included study, slow caffeine metabolizers represented more than half of the study sample. 

To see the full practice question, including the Evidence Statements, Comments and References, click here.

Do Sweeteners Have an Effect on Cardiometabolic Health?

Nonnutritive sweeteners (NNS) may have no short-term effect on cardiometabolic health in adults (e.g. blood pressure, cholesterol, triglycerides), but evidence from longer term studies of cardiovascular health (e.g. hypertension, CVD events, CVD mortality) suggests a possible association between NNS consumption and an increased risk of cardiovascular disease. 

A 2022 systematic review and meta-analysis including 19 RCTs and four prospective cohort studies found little evidence of a short-term effect of NNS intake on markers of CVD (e.g. blood pressure, cholesterol, triglycerides). However, longer term prospective cohort studies suggest an association between higher compared to lower/no NNS intake and increased risk of cardiometabolic disease (e.g. hypertension, CVD events and CVD mortality). Evidence is low and very low certainty. Grade of Evidence C

A 2023 guideline from the World Health Organization (WHO) based on the 2022 systematic review above, makes a conditional recommendation based on low certainty evidence that NNS not be used for noncommunicable disease (e.g. cardiovascular or metabolic disease) risk reduction based on a lack of clear benefit and possible risk of negative health effects. Grade of Evidence C

A 2022 systematic review and network meta-analysis of 17 RCTs (n=1733) found no significant differences in short-term cardiometabolic risk factors (e.g. triglycerides, cholesterol, blood pressure) when substituting sugar-sweetened beverages (SSBs) with beverages sweetened with NNS, although the direction of effect typically favoured NNS. Similarly, no significant associations were found when NNS were compared to water, although the direction of effect typically favoured water. NNS were not clearly associated with adverse effects. Grade of Evidence B

A 2019 systematic review and meta-analysis of 56 studies (21 were RCTs, 35 observational studies) found very low certainty evidence that adults consuming NNS had reductions in systolic and diastolic blood pressure compared to adults in placebo or sugar groups. The results for other cardiometabolic markers (e.g. triglycerides, cholesterol) were not significantly different, although evidence certainty was typically very low. Grade of Evidence C

For further details on the weight outcomes related to NNS use, see Additional Content: What effect do sweeteners (e.g. nonnutritive, artificial, intense, low calorie, sugar substitutes) and sugar alcohols have on weight management?

To see the full practice question, including the Evidence Statements, Comments and References, click here.

Multi-fetal Pregnancy and Nutritional Requirements: Are you Up to Date?

What are the nutritional requirements during multi-fetal pregnancies and do they differ from the recommendations for singleton pregnancies?

There is no evidence regarding the optimal energy, macronutrient or micronutrient needs in multi-fetal pregnancies. However, it is the general consensus that energy, iron, folate and vitamin D needs are higher in multi-fetal than in singleton pregnancies. DHA needs may also be higher in multi-fetal pregnancies and calcium needs are not clear.

As a practical guide in lieu of evidence, the following nutrient intakes have been suggested by various reviews or guidelines:

• 3000 to 4000 kcal daily depending on prepregnancy BMI

• Macronutrient distribution of 20% of calories from protein, 40% of calories from carbohydrate and 40% of calories from fat

• 300 to 1000 ug folic acid supplement daily

• 200 to 4000 IU vitamin D supplement daily

Although iron needs are higher and iron deficiency is more common in multi-fetal compared to singleton pregnancies, there is little national or international guidance regarding routine iron supplementation in multi-fetal pregnancies. Institute of Medicine (IOM) guidelines from 1990 suggest that all individuals with multi-fetal pregnancies take a 30 mg elemental iron supplement daily starting at week 12 gestation. It would be prudent to individualize iron supplementation in this population. 

Country-specific Guidelines
A 2023 comparative review of guidelines from seven countries (Australia, Canada, France, Germany, New Zealand, the U.K. and the U.S.) found that none made recommendations regarding nutritional recommendations in twin pregnancies.

NICE guidelines recommend that individuals with twin pregnancies be given the same nutritional advice as individuals with singleton pregnancies, although they should be checked for iron and folate deficiency at 20, 24 and 28 weeks gestation.

A 2022 narrative review found that although energy needs are generally assumed to be higher in multi-fetal than in singleton pregnancies, this is a theoretical assumption and there is a lack of evidence examining energy needs in multi-fetal pregnancies. In general, energy intakes ranging from 3000 to 4000 kcal daily (depending on prepregnancy BMI) have been recommended. The authors recommend a macronutrient distribution of 20% of calories from protein, 40% of calories from carbohydrate and 40% of calories from fat. Grade of Evidence C

Although an increased risk of iron-deficiency anemia, folate deficiency anemia and vitamin D deficiency as well as low levels of DHA have been noted in multi-fetal pregnancies, the above review concluded that there is no high quality evidence to guide intake or supplementation recommendations in this population. Folic acid supplements ranging from 300 to 1000 ug daily, vitamin D supplements ranging from 200 to 4000 IU daily and iron supplements ranging from 27 to 30 mg daily have been recommended. Grade of Evidence C

No recommendations for DHA supplementation were made. Studies of calcium levels in multi-fetal pregnancies provided mixed results. Other micronutrients have not been adequately studied. Grade of Evidence D

A 2021 systematic review of 13 observational studies found that vitamin D and iron levels may be decreased in multi-fetal pregnancies Grade of Evidence C, while more research is required to define other micronutrient needs Grade of Evidence D.

Nutritional research examining multi-fetal pregnancies has primarily been conducted in twin pregnancies. 

See Additional Content: What is the recommended weight gain during multi-fetal pregnancies?

To see the full practice question, including the Evidence Statements, Comments and References, click here.

Looking for more content on Multi-fetal pregnancy? Check out the Pregnancy: Multi-fetal Knowledge Pathway.

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Health Canada's New Supplemented Food Labels Webinar

Did you know the PEN Team recently moderated Health Canada's webinar "What you need to know about the new supplemented food labels/Apprenez-en plus sur les nouvelles étiquettes des aliments supplémentés"? It was in such high demand that the webinar registration filled up fast and the PEN Team had to cap the registration limit at 570 people to ensure we didn't break Zoom!

The webinar provided an important update for dietitians on new supplemented food regulations. The update included: what supplemented foods are and how to recognize them, how to read labels to ensure safe and appropriate consumption and informed choice, and how supplemented foods differ from other foods and health products based on the label information. Health Canada Staff also talked about the Supplemented Food Labelling Awareness Initiative, including the various communication tools and materials that dietitians can use to help spread the word about supplemented foods, including social media posts and supporting visuals, blog posts and fact sheets.

If you missed the webinar or weren't able to register, don't worry! The webinar was recorded and has been posted on the Dietitians of Canada website.